Monday, August 25, 2014

History of chlorpromazine

Chlorpromazine is dimethylaminopropyl-chloro-phenothiazine.

From molecules


Forerunners of chlorpromazine were promazine and diethazine (A.E. Caldwell, 1970).

From molecules



Chlorpromazine was first synthesized in the laboratory in 1950. Though many drugs like LSD and aspartame are chance discoveries, chlorpromazine may be regarded as a product of successful drug engineering.

In its initial uses, chlorpromazine was given for postoperative shock or severe traumatic shock. In combination with small amounts of weak general anesthetics, chlorpromazine allowed surgeons to perform major operations that were not possible with the use of general anesthetics alone. In order to prevent surgical shock, the entire autonomic nervous system must be inhibited. Chlorpromazine is an autonomic stabilizer, an adrenolytic, parasympatholytic and nearly non-antihistaminic phenothiazine that has great central activity with relatively low toxicity (A.E. Caldwell, 1970).

Subsequently chlorpromazine gained a reputation as an antipsychotic drug. The clinical reports agree in large measure that chlorpromazine appears to be useful in the management of agitation and manic states in psychoneurotic patients. Clinical reports from 1955 revealed the novelty and effectiveness of chlorpromazine at that time. Bleuler and Stoll wrote,
"... reserpine and chlorpromazine soothe and relax patients to an extent formerly unknown to the doctors writing this report ... after 2-3 days of excessive sleeping, from which the patient can be awakened, the patient's mood is more indifferent, less impulsive, quieter, and more relaxed." (M. Bleuler, 1955)

Chlorpromazine has been beneficial in a variety of conditions presenting a picture of psychomotor excitement. At the time, it was considered to be an advance over sedating drugs or physical restraints, but chlorpromazine is not in use anymore.  It has been replaced by newer drugs haloperidol and risperidone.

At the time when chlorpromazine became popular, physicians said that the sedative effect of chlorpromazine is not associated with clouding of consciousness, impairment of judgment or disinhibition of affect; that chlorpromazine can reduce severe anxiety, diminish phobias and obsessions, reverse or modify a paranoid psychosis, quiet manic or extremely agitated patients, and change the hostile, agitated, demented patient into a quiet, easily managed patient. But its not in use anymore, calling into question the effectiveness of the drug. 

Chlorpromazine cannot be labelled as an addictive drug by any means, because often patients do not comply with taking it. Chlorpromazine is not considered to be a drug of abuse, and it is not reported to cause euphoria.

According to Caldwell, chlorpromazine is one of the most important drugs in the treatment of wild animals and in their relocation to preserve wildlife.

In 1954, it was thought that chlorpromazine might block the effects of LSD or mescaline. However, some humans reported an unpleasant intensification of LSD effects when combined with chlorpromazine or reserpine. Ketanserin, which binds 5-HT2A receptors, appears to be a more specific drug for antagonizing LSD and mescaline intoxication than chlorpromazine.

The average daily dose of chlorpromazine is 300-500 mg by mouth, which is equivalent to a dose of 75-150 mg intramuscular. If chlorpromazine is given intravenously it must be diluted with glucose to avoid irritation with the venous walls.


Reference

Caldwell A. E. Origins of psychopharmacology, from chlorpromazine to LSD. Charles C. Thomas: Springfield, 1970. 

original publish date: March 14, 2012

Friday, August 22, 2014

Reserpine and chlorpromazine, two antipsychotic drugs

From Reserpine


In the late fifties, Dr. Nathan Kline treated schizophrenia patients with the drug reserpine, an alkaloid isolated from the plant Rauwolfia serpentina. The antipsychotic drug chlorpromazine, which was synthesized in the laboratory, appeared around the same time. In 1955, Bleurer and Stoll wrote,
"...reserpine and chlorpromazine soothe and relax patients to an extent formerly unknown to the doctors writing this report. . . after 2-3 days of excessive sleeping, from which the patient can be awakened, the patient's mood is more indifferent, less impulsive, quieter, and more relaxed."
Chlorpromazine and reserpine have affinity for both dopamine and serotonin receptors.  The antipsychotic effect of these drugs is thought to be related to changes caused in endogenous levels of dopamine and serotonin, or at the level of dopamine and serotonin receptors, in the patient.


References

BLEULER, M. and W. A. STOLL (1955). Clinical use of reserpine in psychiatry: Comparison with chlorpromazine. Ann. N. Y. Acad. Sci. 61, 167-173. DOI:10.1111/j.1749-6632.1955.tb42463.x



Monday, August 18, 2014

Intensification of LSD effects by reserpine, human studies

Antipsychotic drugs including reserpine and chlorpromazine do not always block LSD intoxication. In some cases, LSD responses are heightened after acute reserpine treatment. Three independent studies from 1957 to 1965 showed this to be the case.

In 1965, Resnick studied drug-drug interactions between reserpine and LSD in 3 male volunteers. Reserpine (Serpasil) 500 mg/day was administered for two weeks, then each participant had a session with 75 ug LSD.
"All three subjects volunteered the information that, following reserpine treatment for two weeks, the experiences produced by LSD-25 were very markedly enhanced." (O. Resnick, 1965)
In 1963, in an article from the American Journal of Psychiatry, the interactions between LSD and reserpine in patients with chronic schizophrenia were discussed. Freedman wrote,
"In collaboration with Benton, 14 chronically schizophrenic women were tested. Two days after 10 mg of reserpine the patients felt recovered from the reserpine; the only sign of an altered brain milieu was the miosis. They then received 120 ug LSD-25 and showed prolonged and toxic reactions: marked tremor and akathisia in the majority and in 1 an occulogyric crisis. Each felt the drug was less pleasant than her control LSD-25 and that the effects lasted longer." (D.X. Freedman, 1963)
Isbell and Logan studied 12 criminals who were serving sentences for violations of the Harrison Narcotic Act. They reported that reserpine treatment did not block the LSD psychosis, and may make it worse.
“The combinations of reserpine and LSD were so disagreeable that the patients were persuaded to complete all the experiments only with the greatest difficulty. In addition to the usual symptoms experienced after LSD, the patients reported other symptoms, which seemed to be of two sorts: first, the usual side-effects of reserpine such as nasal stuffiness, nausea, diarrhea, vomiting, lethargy, weakness, and dizziness on standing, second, severer mental effects. The latter included nervousness and confusion, which exceeded that experienced after LSD alone." (H. Isbell, 1957)

Table 3 below shows the "patients worse" result, when given LSD plus reserpine.

From Reserpine


Most of the human participants had a significant change in perception with reserpine plus LSD, and the evidence shown here is that reserpine gave no particular alleviation of the LSD effect. The unpleasant intensification of effects produced by reserpine plus LSD suggest that reserpine should be avoided before or during LSD use.

Reserpine releases 5-HT from bound form, and it is often cited for the monoaminergic depletion and depression theory, since it is known that normal people taking reserpine become clinically depressed.  If reserpine releases a larger than normal amount of 5-HT in the patients taking it and LSD, and these subjects report an intensification of LSD effects, then high levels of non-bound 5-HT would be indicated in causing the hallucinogenic effects of LSD.  The interactions between LSD and reserpine, which have been reported by three independent studies, would seem to indicate that the hallucinogenic effects of LSD could be mediated by freely circulating 5-HT.


References

Resnick, O., D. M. Krus and M. Raskin (1965). Accentuation of the psychological effects of LSD-25 in normal subjects treated with reserpine. Life Sci. 4, 1433-1437. DOI:10.1016/0024-3205(65)90022-6

FREEDMAN, D. X. (1963). Psychotomimetic drugs and brain biogenic amines. Am. J. Psychiatry. 119, 843-850.

ISBELL, H. and C. R. LOGAN (1957). Studies on the diethylamide of lysergic acid (LSD-25). II. effects of chlorpromazine, azacyclonol, and reserpine on the intensity of the LSD-reaction. AMA Arch. Neurol. Psychiatry. 77, 350-358.





Friday, August 15, 2014

LSD stunts worm development

From LSD research

In 1960, Sankar reported that LSD retards the growth of meal worm (Tenebrio Molitor) larvae. Three worms receiving LSD died.

From LSD research

Group I received the basal diet consisting of 77% corn meal, 15.4% bran, and 7.6% wheat germ supplemented with 1% yeast extract. Group II received the same diet except that 2.5 mgm LSD were added per 10 gm of diet. One problem with this study was the large dose of LSD given to the worms.

The researchers attempted to reverse LSD treatment with reserpine. As shown in Table 2 (below), the control group had a weight of 45 g at the end of 10 days, while groups on the LSD and LSD-reserpine diets had weights of 17.7 and 8.4 g. Unfortunately, the larvae treated with LSD plus reserpine fared poorly, weighing 1/5 of a typical mealy worm by the end of the experiment.

From LSD research


The results suggest that LSD and reserpine produce a drastic effect on larvae body weight compared to LSD alone. Similarly, humans receiving a combination of reserpine and LSD report more severe symptoms than when receiving either drug alone.


Reference

SANKAR D. V., A. KOPELMAN, P. SCHILDER and E. GOLD. (1960). Effect of lysergic acid diethylamide on larval growth. Nature 187, 153-154. DOI:10.1038/187153a0

Monday, August 11, 2014

Methysergide fish surfacing reaction

Methysergide, also referred to as UML-491, causes the fish surfacing reaction in the same way that LSD does, but a higher dose is needed. In goldfish, methysergide is about 250X less potent than LSD at eliciting the reaction. The figure below shows the fish surfacing curve for methysergide. A concentration of 50 ug/mL of UML-491 in the outside liquid gave approximately the same per cent of goldfish reacting as 0.2 ug/mL LSD.



Methysergide is considered to be a hallucinogenic drug in humans. Just as a larger dose of methysergide is needed to elicit the fish surfacing reaction, a larger dose of methysergide is needed for human effects.



Reference

Gettner, H. H., A. Rolo and H. A. Abramson (1965). Lysergic acid diethylamide (LSD 25). 36. comparison of effect of methysergide (UML 491) on goldfish and siamese fighting fish. Journal of Psychology 61, 87-92.

original publish date: October 1, 2007

Friday, August 08, 2014

Vibrating fish behavior

In 1956, Doris Keller and Wayne Umbreit reported that LSD caused "vibrating" behavior in guppy (Lebistes reticulatus).

Guppy behavior remained abnormal for as long as one week after LSD treatment.  From the Science paper that published their discovery,
“The aberrant behavior consisted of periods of normal behavior interspersed at intervals (perhaps every 10-20 minute) with periods of LSD-type behavior.” (D.L. Keller, 1956)
The authors reported that reserpine dissolved in the water (20 ug/mL for 3 days) restored normal guppy behavior, but this reserpine-LSD antagonism has not been found in all studies. For example, meal worms fare worse on a reserpine-LSD diet and human beings have reported an unpleasant intensification of LSD effects when combined with reserpine.

The researchers hinted at an underlying problem with their study.
"We have so far been unable to devise a quantitative method for study of the behavior pattern and are therefore limited at the moment to descriptions of its nature." (D.L. Keller, 1956)


Reference

KELLER, D. L. and W. W. UMBREIT (1956). Chemically altered permanent behavior patterns in fish and their cure by reserpine. Science. 124, 407. DOI:10.1126/science.124.3218.407

Monday, August 04, 2014

Who was Dr. Harold A. Abramson?

H. A. Abramson was one of the most prevalent LSD researchers of the 20th century.

From LSD fish
Abramson spent his life as a clinical allergist, and he had an intense interest in the actions of LSD. He did studies involving human subjects, LSD, and psilocybin, and he pioneered the LSD fish surfacing reaction. He was involved in research with LSD analogs including methysergide and BOL-148, and he studied cross-tolerance between LSD and these drugs in human subjects. He wrote a series of 40 papers about "Lysergic acid diethylamide."

At a conference on LSD in 1959, when asked about the mechanism of action of LSD, Abramson said,
"If I were to say what LSD does, I would refer to experimental work I have done on the Siamese fighting fish, where 1 ug/kg of potassium cyanide (a cytochrome oxidase inhibitor) and sodium azide and LSD will act in very much the same fashion: The fish will be in a nose-up, tail-down stupor, lasting for days in the case of sodium azide, and for a shorter period in the case of potassium cyanide, because it is more rapidly oxidized. We can produce the same effect with hypoxia." (H.A. Abramson, 1959)
Early in his career, Abramson acquired skills in basic immunology, human physiology and pharmacology. He spoke about his transition to LSD from private practice at a conference in 1959.
"About 30 years ago, Dr. Fremont-Smith and I were tutors together at Harvard in the Division of Biochemical Sciences. My main interests originally were physical chemistry and immunology. About 1935, I began the private practice of medicine in New York. Though I had been teaching immunology, I found that conventional treatment yielded very poor results in the many cases of eczema and asthma which I met in practice. It was Dr. Fremont-Smith, by this time in New York, who made me realize that I knew a lot about allergy, but very little about patients. In going over my cases with him, I learned how to appraise an illness, not only in terms of the organic factors, but from the standpoint of the individual as a whole. Soon, I was practicing some psychiatry under his guidance. Realizing that my interests lay in psychiatry and psychotherapy, I proceeded to get training in these areas. But one of my difficulties was being unable to bring the laboratory into the area of psychiatry in the way in which I had been accustomed. I had been working with mathematics and surface chemistry and was really very concerned about the lack of contact between psychiatry, as I knew it then, and the laboratory. Then I saw some papers on LSD. These studies seemed to me to bring the laboratory and psychiatry together. I began to work with LSD in 1951, work which has given me great satisfaction, because it involves my interests in psychoanalysis, psychotherapy, enzyme reactions, and surface chemistry, as well as biochemistry and pharmacology." (H.A. Abramson, 1959)

Abramson frequently wrote about the usefulness of LSD to treat "allergic" phenomena.  He was familiar with the discovery and controversy surrounding the use of LSD and seemed to believe that LSD could be used therapeutically by the medical community. 
"The discoveries of Hoffman have opened new routes to medical progress." (H.A. Abramson, 1965)
In fact, Abramson cited the huge disservice done to the medical community by associating LSD with brain damage, when successful uses of LSD to treat migraine and alcoholism had been identified.
“It seems important to stress at this time that many derivatives of LSD play a most important role in medical treatment. To label any one of these derivatives as the cause of “chronic brain damage” without direct evidence, validated statistically, constitutes a disservice to science and to the practice of medicine… Let us hope that the anxieties of a small group will be replaced by a more hardy spirit of inquiry and scientific investigation.” (H.A. Abramson, 1964)
Abramson did not view LSD as a panacea for everything.  He zeroed in on the potential use of LSD and methysergide for the treatment of migraine and similar phenomenon especially allergic phenomenon.

Towards the end of his research career, Abramson began to have some interesting ideas about the relation between electronic desaturation of certain molecules and drug psychosis-producing ability. In certain hypnotic drugs, he pointed out that if a double bond is present in an unsaturated hydrocarbon, the unsaturated compound is more active than the saturated analog.
"The study of derivatives of arachidonic acid might be another part of the still undisclosed chemical mechanisms which produce mental illness in man.” (H.A. Abramson, 1979)


Reference

Abramson H. A. The use of LSD in psychotherapy. Transactions of a conference on d-lysergic acid diethylamide (LSD-25). Madison Printing Company: Madison, New Jersey, 1959.

ABRAMSON H. A. (1964). Antiserotonin Action of Lsd-25 and Other Lysergic Acid Derivatives: Fact and Fiction. The Journal of asthma research, 15, 207-211.

Abramson H. A. and A. Rolo (1965). Lysergic acid diethylamide (LSD-25). 38. Comparison with action of methysergide and psilocybin on test subjects. The Journal of asthma research, 3, 81-96.

Abramson, H. A. and H. H. Gettner (1979). Double bonds, aliphatic chains, and hallucinogens, updated. The Journal of asthma research, 16, 120.

original publish date: October 21, 2012

Friday, August 01, 2014

pH 5.0 prevents fish surfacing reaction

Betta fish show a "surfacing reaction" when LSD is added to the tank water. About 10 minutes after 1 ug/mL LSD is added to water, almost 100% of fish ascend to the surface of the tank and swim very slowly or not at all.

Abramson and Gettner attempted to block the LSD surfacing reaction in goldfish by lowering the water pH. In a bowl at pH 5.0, only 30% of the fish demonstrated the fish surfacing reaction. When shifted to pH 5.8, nearly all of the fish began the surfacing reaction.  Thus a pH-dependent effect was demonstrated.

From LSD fish



The authors suspected that pH affects the absorption of LSD across the gills. They wrote:
“Alkaloids are not absorbed to any extent from the stomach when the reaction of the gastric juice is strongly acid. If the gastric juice is rendered alkaline, however, alkaloids are rapidly absorbed from the ligated stomach. It is of interest that absorption slows at about pH 5.0 and is fairly rapid at pH 6.0.” (H.H. Gettner, 1973)
Using a different methodological approach, the researchers dipped goldfish for 30 seconds in an LSD-containing solution, and then placed them in normal tank water. Drug concentrations in the dipping tank ranged from 5 to 50 ug/mL LSD. About 70% of the fish that were briefly dunked in LSD-containing water still demonstrated the fish surfacing reaction, but recovered more quickly than fish who were immersed in LSD-containing water for hours. The dotted lines in the figure below represent the die-away curves for fish that were dipped for 30 s only, which demonstrated that LSD can be rapidly absorbed by the animal body. The surfacing reaction was more persistent when fish were immersed in LSD solutions (solid black lines).

From LSD fish


Similar curves were obtained by dipping goldfish for 30 seconds into solutions of methysergide.


Reference

Gettner H. H., P. A. Carone and H. A. Abramson. (1973). Lysergic acid diethylamide (LSD 25). XXXX. Effect of pH on transport of methysergide and LSD 25 across gill membrane. J. Psychol. 84, 111-118.

Monday, July 28, 2014

Fish surfacing reaction



Failure of normal behavioral responses is a characteristic effect of LSD-25.

In fish, LSD disrupts the normal patterns of swimming. When a Siamese fighting fish, Betta splendens, is placed in 100 mL fresh spring water containing 1 ug/mL LSD, it moves to the surface of the water, in a nose-up, tail-down position. Swimming movements are significantly reduced, and the fish remained physically immobilized in a statue-like position for many hours. Another effect was the darkening of Betta's basic body color, which faded slowly as recovery occurred. Abramson and colleagues noted that juveniles were more sensitive to color changes than adult Bettas (Abramson,H.A. 1954).


Six behaviors were identified for LSD-intoxicated Bettas.
1a. Backward movements.
1b. Head up, and the body is suspended in the vertical plane. In the maximum stage of narcosis the snout is kept at the surface. As the effects begin to wear off, the fish sinks slowly below the surface until after six hours it might take a position two inches below the surface.
1c. "Cartesian diver" effect. Treated fish sink or rise very slowly in near-vertical plane without visible body movement except by means of pectoral fins.
1d. Treated fish exhibit kinking in their body conformation.
1e. "Trancelike" effect.
1f. Movements of fish were slow and deliberate as compared with the typical swift and sudden movements of normal fish.

Just how arbitrary are these descriptions? In Cold Spring Harbor, 1956, four judges, two zoology majors, and two physiology majors in their senior year of college spent approximately eight hours observing fish in water containing LSD. Only one response was measured on a given trial. As shown in the table below, there was a significant amount of agreement between judges about the 'quiescent state' parameter (Arbit,J. 1957).  In general, the judges agreed that the Betta fish swimming in LSD-containing water showed behaviors of 'quiescent state', 'darkened pigment', and 'slow movements'.
The fish surfacing reaction has been studied in other species of fish too.  The figure below shows the LSD surfacing curve for goldfish.  There is a time- and dose-dependent effect.  In water containing 0.5 ug/mL LSD, about 95% of the fish showed a nose-up, tail-down reaction within 20 minutes (Abramson,H.A. 1979).  The surfacing reaction was less pronounced in water containing 0.2 ug/mL or 0.1 ug/mL LSD, with less fish being affected less rapidly.

From LSD fish


Some of the largest fish studied have been carp. As shown in the figure below, control fish spend over 90% of their time at the bottom of the tank, (bottom right, top right).  However, after 45 minutes in water containing 2 ug/mL LSD, carp spent more time at the surface (bottom left) (Abramson,H.A. 1962).


Harold Abramson pioneered the fish surfacing reaction, and did most of the studies presented above.  However, similar results were obtained by R. Chessick, who studied the effects of LSD on Betta, guppy (Lebistes reticulatus), and white cloud (Tanichthys albonubes). The effects common to all species in LSD-containing water were reported to include darkening of body color and less spontaneous activity (Chessick,R.D. 1964).



References

ABRAMSON, H. A. and L. T. EVANS (1954). Lysergic acid diethylamide (LSD 25). II. psychobiological effects on the siamese fighting fish. Science. 120, 990-991. DOI:10.1126/science.120.3128.990

ARBIT, J. (1957). Effects of LSD-25 upon betta splendens: Reliability of a bioassay technique. J. Appl. Physiol. 10, 317-318.

Abramson, H. A., H. H. Gettner, M. P. Hewitt and G. Dean (1962). Effect of lysergic acid diethylamide on the surfacing behaviour of large carp. Nature. 193, 320-321. DOI:10.1038/193320a0

CHESSICK, R. D., J. KRONHOLM, M. BECK and G. MAIER (1964). Effect of pretreatment with tryptamine, tryptophan and dopa on LSD reaction in tropical fish. Psychopharmacologia. 5, 390-392. DOI:10.1007/BF00441449

Abramson, H. A., H. H. Gettner, P. A. Carone, A. Rolo, and L. Krinsky (1979). The intracranial injection of drug in goldfish. I: Hallucinogens and their antagonism to smooth muscle activity. The Journal of asthma research, 16, 55-61.

original publish date: September 22, 2007

Monday, February 01, 2010

BOL-148

BOL-148 is the 2-brom derivative of LSD. There is a Bromine (Br) in place of Hydrogen at position 2.


From molecules


In spite of its close structural relationship to LSD, BOL-148 has no psychedelic effects. Among the LSD analogs, BOL-148 is especially important because it indicates that substitution at the 2-position changes the activity of the whole molecule, as outlined by the studies below.

In 15 healthy males, doses of 75-110 ug/kg BOL-148, which 100X exceed an effective dose of LSD, caused no change in pupillary dilation, patellar reflex, or blood pressure (H. Isbell, 1959). BOL-148 did not alter the behavior of 6 individuals with schizophrenia, when given at 10X the dosage of active LSD, although for BOL-148 these doses may have been too low to observe any effect. One mg BOL-148 twice a day for 2 weeks, or 5 mg for 3 days had no evident effect on their psychoses (W.J. Turner, 1958).

With newly developed drugs and low doses of known drugs, there is frequently a problem in deciding whether the drug has an effect on the EEG. Generally where there is no EEG effect, no drug effect is expected. There is evidence of the contrasting pharmacological effects of LSD and BOL-148 on the EEG. While LSD affects the EEG in doses of 100 ug/kg, BOL-148 in doses of 100+ ug/kg are reported to be without effect on the EEG. BOL-148 did not cause any sign of the fast electrical activity or alerting behaviour seen with injections of LSD in cats, even when doses of up to 100 ug/kg of BOL-148 were used intraventricular, to avoid the blood-brain barrier (P.B. Bradley, 1956). BOL-148 is reported to produce no EEG changes in Macaca mulatta, in high dose ranges 110-175 ug/kg (R.R. Monroe, 1961). Saline gave the same response as 1000 ug/kg BOL-148 in cats with permanently implanted EEG electrodes (E. Eidelberg, 1965). In rabbits, 500 ug/kg BOL-148 failed to produce EEG alerting for longer than 15 minutes (A.K. Schweigerdt, 1966). These studies indicate a lack of effect of BOL-148 across a range of species.

BOL-148 has a very slight change in molecular structure compared to LSD, but it has none of the behavioral effects of LSD. LSD caused behavioral arousal in cats whereas BOL-148 produced mild sedation, when the two drugs were administered intraventricularly (P.B. Bradley, 1956). In rabbits, LSD enhances eyeblink conditionining, whereas BOL-148 had a neutral effect (J.A. Harvey, 2003). No affective changes in Papio papio were observed after BOL-148 in doses of 2-4 mg/kg (M.D. Fairchild, 1980).

Table 3 below shows the questionnaire responses for LSD and several LSD derivatives. LSD is the most potent drug, and caused the most positive responses on the questionnaire. BOL-148 is on this table, and there were few positive responses on the questionnaire at doses of 80 ug/kg, or 50 times the active dose LSD. This shows a lack of effect of BOL-148 as reported by human volunteers.

From LSD congeners and other human hallucinogens


There is some evidence that BOL-148 pre-treatment protects against LSD psychosis. Studies in rabbit have shown that BOL-148 1 mg/kg had no direct temperature effect - as LSD does - but prevented the pyretogenic actions of LSD (A. Horita, 1958). In humans, BOL-148 did not function as a direct LSD antagonist since intravenous injections of BOL-148 at the height of a LSD trip did not cancel the LSD effects, but pre-treatment with BOL-148 in nonpsychotic humans did produce tolerance to the LSD reaction, though the tolerance-producing effect of BOL-148 for equal weights of LSD is much less, approximately 1/30 that of LSD and the attenuation of the LSD reaction observed after pre-treatment with BOL-148 is still less than that which occurs after pre-treatment with LSD. (H. Isbell, 1959)

In an experiment with 10 men, pretreatment with BOL-148 for 5 days (1 mg BOL-148 three times daily) significantly attenuated LSD 0.5-1.5 ug/kg psychosis. As shown in Table 3 (below), blood pressure, pupil size and number of positive responses to questionnaire were reduced during LSD challenge 5 days after BOL-148 pretreatment (Isbell, H. 1959).

From LSD congeners and other human hallucinogens


Some assays have indicated similarities between LSD and BOL-148. For example, LSD and BOL-148 were found to have the same affinity for beta-adrenergic receptors (A. Dolphin, 1978), and were equally effective as MAO and acetylcholinesterase inhibitors in histochemical analysis of rat brain (T.R. Shanthaveerappa, 1963). However it is important to keep in mind that these samples did not involve the whole organism. More research in needed into the general significance of the 2-position for the pharmacological and EEG effects of LSD.

There is one report from 1957 indicating that BOL-148 may function as a hallucinogen in high doses. Two normal volunteers experienced psychic effects when BOL-148 was administered intravenously to total doses of 18 and 22 mg, or equivalent to ~200 LSD doses.
"In man small doses of bromo-LSD are said to produce none of the bizarre psychic effects noted with LSD but this is not the case when bromo-LSD is administered intravenously in large doses. Thus, when constant intravenous infusions of bromo-LSD were given to normal subjects, both experienced psychic changes, which became more severe as the infusion continued and persisted for 3 to 4 hours after the infusion was stopped. No hallucinations were noted but there were feelings initially of drowsiness, depression, anxiety, and apprehension followed by feelings of irritation, restlessness, and tenseness, and later, intensely disagreeable sensations of unreality and depersonalization, inexplicable feelings of strangeness and mild confusion." (R. Schneckloth, 1957)
A relatively large body of work exists on human studies with BOL-148, making it one of the most well characterized LSD analogs. BOL-148 shows that structure-activity relationships can be quite revealing about the mechanism of action of LSD, since substitution at the 2-position can change the activity of the whole molecule. Another important research finding related to BOL-148 research is that LSD does not induce a psychosis by creating a relative deficiency of 5-HT within the brain. BOL-148 has been shown to have more anti-5-HT activity than LSD in vitro and in vivo, thus if LSD worked by blocking 5-HT neurotransmission, BOL-148 would be expected to be a more potent hallucinogenic drug, but BOL-148 is inactive on many accounts.


References

BRADLEY P. B. and A. J. HANCE. (1956). The effects of intraventricular injection of d-lysergic acid diethylamide (LSD 25) and 5-hydroxytryptamine (serotonin) on the electrical activity of the brain of the conscious cat. J.Physiol. 132, 50-1P.

Dolphin, A., A. Enjalbert, J.P. Tassin, M. Lucas and J. Bockaert (1978). Direct interaction of LSD with central "beta"-adrenergic receptors. Life Sci. 22, 345-352.

Eidelberg E., M. Long and M. K. Miller. (1965). Spectrum analysis of EEG changes induced by psychotomimetic agents. Int.J.Neuropharmacol. 4, 255-264.Fairchild M. D.,

D. J. Jenden, M. R. Mickey and C. Yale. (1980). EEG effects of hallucinogens and cannabinoids using sleep-waking behavior as baseline. Pharmacol.Biochem.Behav. 12, 99-105.

Harvey J. A. (2003). Role of the serotonin 5-HT(2A) receptor in learning. Learn.Mem. 10, 355-362.

HORITA A. and J. H. GOGERTY. (1958). The pyretogenic effect of 5-hydroxytryptophan and its comparison with that of ISD. J.Pharmacol.Exp.Ther. 122, 195-200.

ISBELL H., E. J. MINER and C. R. LOGAN. (1959). Relationships of psychotomimetic to anti-serotonin potencies of congeners of lysergic acid diethylamide (LSD-25). Psychopharmacologia. 1, 20-28.

ISBELL H., E. J. MINER and C. R. LOGAN. (1959). Cross tolerance between D-2-brom-lysergic acid diethylamide (BOL-148) and the D-diethylamide of lysergic acid (LSD-25). Psychopharmacologia. 1, 109-116.

MONROE R. R. and R. G. HEATH. (1961). Effects of lysergic acid and various derivatives on depth and cortical electrograms. J.Neuropsychiatr. 3, 75-82.

SCHNECKLOTH R., I. H. PAGE, F. DEL GRECO and A. C. CORCORAN. (1957). Effects of serotonin antagonists in normal subjects and patients with carcinoid tumors. Circulation. 16, 523-532.

Schweigerdt A. K., A. H. Stewart and H. E. Himwich. (1966). An electrographic study of d-lysergic acid diethylamide and nine congeners. J.Pharmacol.Exp.Ther. 151, 353-359.

SHANTHAVEERAPPA, T. R., K. NANDY and G.H. BOURNE (1963). Histochemical studies on the mechanism of action of the hallucinogens D-lysergic acid diethylamide tartrate (lsd-25) and D-2-bromo-lysergic acid tartrate (bol-148) in rat brain. Acta Neuropathol. 3, 29-39.

TURNER W. J. and S. MERLIS. (1958). Chemotherapeutic trials in psychosis. III. 2-Brom-d-lysergic acid diethylamide (BOL 148). Am.J.Psychiatry. 114, 751-752.

Wednesday, November 11, 2009

LD50, lethal dose 50

Terence McKenna explains the concept of LD50.
"We want to take an excursion here and learn a little pharmacology. If you're going to talk about pharmacology, there is one concept that you should get straight, and that's called LD50. It means "lethal dose 50". What does this mean? Well, you have 20 rats and you give them a certain amount of, let's say, mescaline. When half the rats die, that dose, expressed as milligrams per kilogram of body weight, is called the LD50. And when pharmacologists assess the danger in a drug, they ask the following question, "what is the relation of the LD50 to the effective dose?", and if the LD50 of a drug is only 20 times the effective dose, that's considered an incredibly toxic, dangerous, and dubious drug. A good drug is a drug where the LD50 is 200 times more than the effective dose. In the case of LSD, the LD50 for man has never been determined. That's how safe LSD is. We're talking about lethality here, not you know. So people say, "Well are there unsafe psychedelics?" Well, yes, you just look up the LD50s, line them up, and see which ones have the better ratios. By that measurement, by that standard, LSD is the most desirable. But the LD50 of psilocybin is very impressive. You can take 100 times the effective dose of psilocybin and expect to live. Mescaline, not. Mescaline has a bad profile. As an amphetamine, if you took 20 times the effective dose of mescaline, you would probably die. Of course, an effective dose of mescaline is nearly a gram of pure material, 700 milligrams. If you took 20 times 700 milligrams you would be taking nearly 2/3 of an ounce of mescaline..." (Terence McKenna)
The LD50 of LSD varies from species to species. Rabbit is the most sensitive species known, with LD50 of 0.3 mg/kg i.v. The LD50 for rats is ten times higher at 16.5 mg/kg i.v. Mice tolerate 46-60 mg/kg i.v. LSD (Passie et al, 2008). An intraperitoneal dose of LSD 5.0 mg/kg reportedly caused death in a rat within 30-45 minutes and was associated with cardiac irregularities and general rigidity of musculature (Sylar et al, 1971). A too high dose of LSD typically causes animals to expire by paralysis, bradycardia, or respiratory failure; these effects probably involve centers in the caudal brain stem.

In an experiment with Macacus rhesus, one animal received 240 ug/kg and the other 140 ug/kg, which are enormous doses of LSD. In terms of a 70 kg person, the animals received 168 and 98 hits of LSD. These doses did not produce an excited behavior in monkeys as small doses do, but instead produced sedation. The monkeys became quiet and more sluggish around the cage, and did not jump about the cage as they did before. The monkeys lived.


Reference
Passie, T., J. H. Halpern, D. O. Stichtenoth, H. M. Emrich and A. Hintzen (2008). The pharmacology of lysergic acid diethylamide: A review. CNS Neurosci. Ther. 14, 295-314.

Sklar, S., K. A. Nieforth and M. Malone (1971). Synthesis and preliminary screening of N-ethyltryptamine derivatives related to reserpine and lysergic acid. J. Pharm. Sci. 60, 304-306.

Thursday, June 04, 2009

when kids accidentally ingested LSD

There are reports of autistic or schizophrenic children who have taken LSD in a therapeutic setting, with variable effects. What happens when psychologically normal kids accidentally ingest LSD? Here are 3 anecdotal cases.

CASE 1

In 1966 on a Wednesday morning in April, a 5-year-old girl accidentally ingested 100 ug LSD on a sugar tablet in the refrigerator belonging to her 18-year-old uncle. Her name was Donna, but after the trip she substitutes Deborah for herself Donna, and thought that her body had been torn in half. The story told by the interviewing psychiatrist is very descriptive:
"Within an estimated 15 or 20 minutes the patient began to scream and cry, creating a commotion that awakened the household and alerted the uncle to the mishap. She was alternately screaming and silent. During her quiet periods she was motionless and unresponsive and apparently unaware of her surroundings. Physical examination about three hours after ingestion showed a screaming child with a temperature of 99 F (37 C), a pulse rate of 130 beats per minutes, 30 respirations per minutes, dilated pupils, and hyperreflexia. Treatment consisted of bed-rest and intravenous infusion of saline. Blood cell count and findings from examination of the urine were normal. The serum glutamic oxoloacetic transaminase value was elevated to 82 units and the alkaline phosphatase was elevated to 20.1 units."

"After four or five hours of hospitalization and intermittent napping, the patient became relatively calm, unfrightened, and responsive. At the same time she expressed many bizarre and apparently delusional ideas, such as that her body was cut off at the waist, that she was not herself but was a girl named Dorothy (a name similar to her own, Donna), that it was not she but Dorothy who had eaten supper, that she had gone home and her bed was occupied by a girl named Dorothy. The following morning, after an uneventful night's sleep, she seemed superficially responsive and rational. However, she still maintained that Donna had gone home during the night and that she was Dorothy and she wrote her name as Dorothy. In the course of the morning she became better oriented and began to recognize that she was Donna again."

"Psychiatric examination on the afternoon of April 7, about 30 hours after ingestion, showed a quiet, unreactive, apathetic girl. She responded promptly when questioned, and displayed an alertness that was in marked contrast to her prevailing apathetic mood. Her emotional range was very narrow and lacked normal modulation. Her verbalizations, although brief, were responsive and appropriate and she had a fairly good recollection of the events preceding hospitalization. In contrast to her condition of a few hours earlier, she was oriented and lucid. Her thinking was somewhat concrete. She was not able to express subjective feelings or experiences. It was inferred from her refusal to stand her complaint that her legs "hurt" that she was experiencing either paresthesias or a residuum of the preceding day's profound distortion of body image. She described a dream in which "they stole my mommy and tried to cut her in half" which seemed to be expressing the same distortion of body image or body perception." (D.H. Milman, 1967)

A psychiatric evaluation 5 days later showed that Donna was still abnormal and her IQ had dropped. At evaluation five months later, IQ levels had returned to normal, and the girl had returned completely to her typical behavior with flexible thinking processes. At the final examination nine months after the incident, the patient was in first grade and progressing well. She had a normal IQ, good concentration and cheerful mood with logical and appropriate thinking.

The substitution of her name for Dorothy provides an example of "depersonalization" after LSD, which generally refers to one not being oneself. The description of her body being torn in half suggests that she experienced a major alteration in body image.


CASE #2

A 25-month male infant ingested an estimated 200 ug LSD in the form of 2 purple microdots.
"At 10:30 AM on the day of admission the mother noted the onset of unusual behavior in her child: He appeared unsteady and stumbled, he was frightened and screamed while looking at a colored rug, at the ceiling, or upon seeing a housefly, and he frequently opened his eyes widely and covered his ears with his hands as if to block out unpleasant sounds. The mother recalled she had had two tablets of LSD, purple microdots, in her purse; she found the purse opened and both tablets missing. The child was taken to a local hospital where the family's physician noted that the child was in a state of "stark terror." He clung tightly to his mother, screaming at apparent visual hallucinations perceived on the walls of the examining room; he did not fix his gaze on persons or other objects." (B.M. Ianzito, 1972)
The child received an intramuscular injection of 10 mg chlorpromazine at 12:20 PM, one hour after which he had normal vital signs, was quiet, and fixed his gaze on objects for brief periods. Chlorpromazine seemed to be effective in the case of this 2-year old, although in other subjects chlorpromazine has reportedly intensify the LSD experience.


CASE #3

In 1973, a 23-month male infant admitted to hospital had ingested one LSD tablet 2 hr before admission. The child was very hysterical and hyperreactive. He was given 15 mL ipecac syrup to induce vomiting and he was given water, and a urine sample was collected for spectroscopy analysis. At 3 hours, the patient had calmed down and at 4 hours could recognize his mother. He was sent home from the hospital 2 days later in general good condition.

The dosages of LSD given to these 3 children were well above the adult threshold levels, and there was no indication of brain damage. Screaming and crying seemed to be a common reaction to LSD within the first 2 hours. There was a temperature increase to 99 F in the 5-year-old girl, consistent with an emotionally hyperactive state.


Reference

Ianzito B. M., B. Liskow and M. A. Stewart. (1972). Reaction to LSD in a two-year-old child. J.Pediatr. 80, 643-647. 10.1016/S0022-3476(72)80064-7

Milman D. H. (1967). An untoward reaction to accidental ingestion of LSD in a 5-year-old girl. JAMA. 201, 821-825. 10.1001/jama.201.11.821

Mueller R. G. and G. E. Lang. (1973). Fluorescent spectra of lysergic acid diethylamide: observations on a gastric extract. Am.J.Clin.Pathol. 60, 487-492.

Saturday, May 23, 2009

LSD dose

The effective dose of LSD varies enormously among species. In salamander, the effective LSD dosage is 700,000 ug/kg. Intracranial injections of 300 ug/kg in goldfish produce the characteristic LSD fish surfacing reaction. In mouse the effective dose is 180 ug/kg of body weight. With LSD behavioral changes are discernible in rat at 80-160 ug/kg but in the cat at 25 ug/kg. A 20 ug/kg LSD affects pigeons' performance in learned discrimination tasks. In rabbit the effective dose is 15 ug/kg. In man, where we have the advantage of verbal reporting, the effective dose is less than 1 ug/kg. According to Albert Hofmann, the effective human dose of LSD is 0.5 ug/kg.

A flat dosage of 100 ug per person is used commonly in human LSD research. This dosage quantity is convenient to remember because it doesn't take body weight in kilograms into consideration. A dosage of 100 ug per person typically results in dramatic symptoms, but the threshold for activity generally is placed at 20 ug LSD per person.

Very low doses of LSD (4-40 ug per person) were tested in human volunteers by Greiner and colleagues in 1958. Psychic changes were established by way of interviews and measurement of pupil size, heart rate, and galvanic skin response. The data below showed that mood and psychomotor effects were detectable in human volunteers at dosages as low as 4 ug LSD per person, which is approximately 0.05 ug/kg of body weight, or 10 times less than the effective dose according to E. Rothlin and Hofmann. The objective measures showed that the galvanic skin response was activated after only 7 ug LSD per person. There was a dose-dependent increase in pupil size, heart rate, and other parameters.

From LSD dose


The researchers observed sudden shifts in affect in the volunteers after 4 ug, 7 ug, or 12 ug of LSD per person, but no significant changes in thought process or content. This data puts the threshold dose for LSD intoxication at about 20 ug per person.

LSD is one of the most potent drugs known to man. Whereas most drugs are administered at doses of tens or hundreds of milligrams, LSD is active at tens or hundreds of micrograms. The potency of LSD is best compared to other drugs on a log scale, as shown in Figure 1 below. It can be seen that the concentration of an active dose of alcohol is about a million times as great, expressed in terms of weight, as the concentration of LSD.

From LSD dose


Of course, the effective dose of LSD depends highly on the person, set, and setting. The dose threshold may be lower for people who are generally inexperienced with drugs, and higher for alcoholics and drug addicts.
“Familiarity with other drugs which produce psychological changes is also relevant. Alcoholics and drug addicts seem better able to cope with the LSD experience than normal subjects. I have had more difficulty with anxiety and panic in normal subjects than in patients who have had long experience with drugs.” (A. Hoffer, 1965)
Fasting or not can change the effective LSD dose too. Plasma concentrations of orally ingested LSD were twice as much on an empty stomach. The amount of the meal as well as the pH of the stomach will influence LSD absorption.


References

GREINER T., N. R. BURCH and R. EDELBERG. (1958). Psychopathology and psychophysiology of minimal LSD-25 dosage; a preliminary dosage-response spectrum. AMA Arch.Neurol.Psychiatry. 79, 208-210.

Passie T., J. H. Halpern, D. O. Stichtenoth, H. M. Emrich and A. Hintzen. (2008). The pharmacology of lysergic Acid diethylamide: a review. CNS Neurosci.Ther. 14, 295-314.

Thursday, March 05, 2009

LSD absorption and fluorescence

The LSD molecule contains a number of pi-electrons. These pi-electrons absorb electromagnetic radiation very strongly, like many aromatic or conjugated systems. LSD absorption is maximal at 320 nm, and LSD fluorescence is maximal at 435 nm. These values are somewhat flexible depending on the spectrophotometer, with some authors reporting LSD absorption at 325 nm, and LSD fluorescence at 445 nm. The spectroscopic properties of radioactive [3H]-LSD are the same as LSD, with a maximum fluorescence at 445 nm, and an excitation wavelength of 325 nm. For LSD spotted onto chromatography plates, maximum excitation occurs at 330 nm, and emission at 410 nm. Spots of LSD on thin-layer chromatography plates give a violet-blue fluorescence under a UV lamp.

From LSD spectroscopy


Muller and Lang carefully studied the absorption and fluorescence of LSD as a function of pH. As shown in Figure 1 above, there is a minor excitation peak at 240-250 nm in addition to the major excitation peak of LSD at 330 nm. The major excitation peak of LSD could be shifted by placing the LSD sample in either acid or alkali conditions. The major LSD excitation peak was 327 nm in 0.01 N HCl and 319 nm in 0.05 M Na2HPO4. In basic solution, the 319 nm peak was approximately 25% greater in amplitude than the height of 327 nm in HCl. Major emission peaks of LSD were at 420-430 nm, with a shoulder at 536 nm.

In 1971, in situ fluorometry was performed on LSD using quinine as an internal reference. As seen in the figure below, quinine (A2, B2) and LSD (A1, B1) have the same excitation and fluorescence wavelengths.

From LSD spectroscopy


LSD fluorescence can be used to check its potency. Niwaguchi and colleagues found a linear relationship between fluorescence emission intensity and the amount of LSD on thin-layer chromatograms. If the 9,10 double bond of the D-ring is intact, blue fluorescence is observed under UV lamp.


Since the fluorescence emission intensity is proportional to the amount of LSD, the concentration of an unknown LSD solution can be determined with a Farrand or Bowman spectrophotometer. After blanking with water at 300 nm, solutions of LSD are scanned with 350 to 250 nm light, and the maximum absorbance, which occurs at approximately 330 nm, is compared to a standard solution of LSD. As little as 0.001 microgram of LSD, or 1/100,000 of a dose, can be analyzed this way.

LSD is among the most fluorescent substances known. LSD is more strongly fluorescent than N,N-DMT, diethyltryptamine, psilocybin, or mescaline. For comparison, DMT absorbs at 280 nm, and fluoresces at 350 nm. Psilocybin absorbs at 270 nm and fluoresces at 340 nm.

LSD decomposition

It has been reported that LSD loses its fluorescence very rapidly upon strong ultraviolet irradiation, as shown in the decomposition curves below. After just 10-20 seconds of irradiation at 320 nm, the LSD fluorescence reading was significantly diminished.

From LSD spectroscopy


If UV irradiation is continued for up to 60 minutes, a significant amount of decomposition of LSD can be shown by paper chromatography. Only 10% of LSD remained after 60 min UV irradiation while in the control experiment 90% of LSD remained after 17 h standing in the dark.

From LSD spectroscopy


A decrease in LSD fluorescence with irradiation occurs when UV light catalyzes the hydration of LSD to a non-fluorescent derivative. A molecule of water is added across the C9-C10 double bond of LSD to produce the non-fluorescent lumi-derivative. In 1972, Upshall and colleagues described an easy-to-follow procedure for analyzing LSD in human plasma, by measuring the difference in fluorescence (318 nm excitation, 413 nm fluorescence) of plasma extracts before and after intense UV irradiation (at 254 nm). This analytical method (detection of change) is greatly preferable to a direct reading of UV fluorescence in plasma, since the plasma blank reading has sufficient enough magnitude to seriously interfere with the determination of LSD. Upshall determined an average of 1-10 ng LSD per 1 mL human plasma.

From LSD spectroscopy


Upshall's analytical method of differences is superior to spectroscopic techniques that are based on one measurement of LSD fluorescence, because contents of plasma can obscure the native fluorescence of the LSD molecule. When Aghajanian and colleagues measured LSD concentrations in human plasma in 1964, they found a concentration which corresponded to a level of LSD in the plasma that was higher than expected based on a known injection amount. In this case, the contents of plasma may have added to the native fluorescence of the LSD molecule because the researchers obtained a value of 6-7 ng/mL plasma, about 10X higher than expected. Assessment of the difference in fluorescence of plasma extracts before and after intense UV irradiation is the best way to measure LSD concentrations in human plasma.


References

AGHAJANIAN G. K. and O. H. BING. (1964). Persistence of Lysergic Acid Diethylamide in the Plasma of Human Subjects. Clin. Pharmacol. Ther. 5, 611-614. 

AXELROD J., R. O. BRADY, B. WITKOP and E. V. EVARTS. (1956). Metabolism of lysergic acid diethylamide. Nature. 178, 143-144. 10.1038/178143a0

BOYD E. S. (1958). The fluorometric determination of lysergic acid diethylamide and ergonovine. Arch. Int. Pharmacodyn. Ther. 115, 43-51.

Niwaguchi T. and T. Inoue. (1971). Studies on quantitative in situ fluorometry of lysergic acid diethylamide (LSD) on thin-layer chromatograms. J. Chromatogr. 59, 127-133. 10.1016/S0021-9673(01)80012-1

Sperling A. (1972). Analysis of hallucinogenic drugs. J. Chromatogr. Sci. 10, 268-275.

Upshall D. G. and D. G. Wailling. (1972). The determination of LSD in human plasma following oral administration. Clin. Chim. Acta. 36, 67-73.

Tuesday, July 22, 2008

Serotonin in wasp venom and Bufo toads

From LSD research

5-HT is present in the venom of wasp, scorpion, stinging plants, sea anemone and Portugese man-of-war. Poisonous salivary glands of octopus are also known to contain large amounts of 5-HT. Table 8 below shows that scorpion and Bufo marinus contain a high concentration of 5-HT.
From 5-HT pain

Histamine is the other major component in the venom of some wasps. In Table I below, the amount of histamine was quantified relative to the weight in grams (g) of the venom sac. The mean 5-HT concentration in venom was 0.32 mg/g, and the mean histamine concentration was 4.3 mg/g.
From 5-HT pain

Histamine and 5-HT probably contribute to the pain following a wasp sting, since these chemicals cause pain when applied to a blister in human skin.


Reference
Lewis, G. P. 5-Hydroxytryptamine, Lewis, G. P., Ed., Pergamon Press: New York, 1958.
Lyttle T., D. Goldstein and J. Gartz. (1996). Bufo toads and bufotenine: fact and fiction surrounding an alleged psychedelic. J. Psychoactive Drugs. 28, 267-290.

Monday, July 14, 2008

Lugaro cells

The cerebellum mostly contains interneurons. Purkinje cells are the well-known ganglion cells of the cerebellum which contain mostly GABA. Purkinje neurons form powerful inhibitory synapses on neurons in the deep cerebellar nuclei, which directly relay to spinal cord motoneurons. Therefore the inhibitory output of the cerebellum is important for sculpting motor behavior.
Lugaro cells are one class of interneuron in the cerebellum, which were first described by Lugaro in the early nineteenth century. The Lugaro cell is shown in red and Purkinje cells are yellow.

From Lugaro cells

The neuron of Lugaro has been described in the granular layer of various species of mammals including humans. Lugaro neurons are found just inferior to the Purkinje (p) cell bodies. They are positioned between the molecular (m) and granular (g) layers of the cerebellum.
From Lugaro cells


Lugaro cells have thick principal dendrites that emerge from opposite poles of the cell body and extend for remarkably long distances, up to 230-300 um, along the boundary between the Purkinje neuron layer and granular layer. The dendrites appear to contact 5-15 Purkinje cell bodies in a horizontal direction.
From Lugaro cells

Like the dendrites of olfactory and taste sensory neurons, Lugaro cells exhibit specialized dendrites with the ability to sense nearby chemical or mechanical stimuli, therefore Sotnikov included Lugaro cells in a list of possible bipolar sensory neurons, based on morphological criteria. The dendrites of Lugaro cells form an extensive receptive surface that monitors the chemical and physical environment in the vicinity of Purkinje cells. Since its dendrites contact 5-15 Purkinje cells bodies in a horizontal direction, and receive inputs from recurrent branches of Purkinje neuron axons, the Lugaro cells appears to have a role in the sampling and integration of the outputs converging from neighbouring Purkinje cells.

In some instances, Lugaro cells form clusters of 2-5 tightly packed cells. Golgi staining revealed 2 or 3 Lugaro cells impregnated near each other. This dye-coupling could be explained if the dendrites of Lugaro cells contain electrical synapses through which the dye may pass in a bidirectional manner. Lugaro cell dendrites, like other primary sensory neurons of the brain, may form bundles that are connected via electrical synapses and gap junctions at dendrosomatic and dendrodendritic junctions.

From Lugaro cells


The horizontally disposed basket cell axons in the supraganglionic plexus occupy the layer superior to the Purkinje cells. The layer inferior to the Purkinje cell layer is known as the infraganglionic plexus. Lugaro cell dendrite bundles course through the infraganglionic plexus, forming a sheet adjacent to the ganglion neurons of the cerebellum, much like the dendrites of TRN neurons form a layer dorsal to the thalamus. Immunocytochemical investigations have demonstrated GAD or GABA immunoreactivity in the Lugaro cell of the rat and human, indicating its putative GABAergic, inhibitory nautre, and also the presence of the inhibitory amino acid glycine and of a colocalization of glycine and GABA.

Lugaro cell axon

Though little is known about Lugaro cells in general, it is thought that Lugaro cell axons target basket and stellate cells in the molecular layer. The major target of the Lugaro cell axon is the inferior 1/3 of the molecular layer, where the Lugaro cell axon runs with the parallel fibers, giving off branches in the molecular layer. Lugaro cell axon collaterals extend for quite a long distance in the latero-lateral direction, exactly parallel to the parallel fibers, as shown in the figure below.

From Lugaro cells


Sometimes the Lugaro cell axon takes a curving route through the granule layer, before running its parallel course in the molecular layer. The axon dips through the granular layer, then the white matter, before ascending to terminate on basket or stellate cells in the molecular layer. In the figure below, the Lugaro cell axon passes through the white matter before ascending to terminate on target cells about 400 micrometers from the original cell soma. Notice the dendrites of the Lugaro cell are adjacent to Purkinje cell bodies.

From Lugaro cells


The Lugaro cell axon also terminates on Golgi cells in the granular layer. In some cases, the Lugaro cell axon never reascends to the molecular layer in which case the Golgi neurons are its postsynaptic target. According to Dieudonne, the Lugaro cell forms a major input to Golgi cells, and one Lugaro cell may contact up to 100 Golgi cells.
From Lugaro cells

The figure above is a Lugaro cell from rat cerebellum that has been stained with the Golgi technique. The thick dendrites are confined to the region of Purkinje cell bodies. The axon, marked by a carrot, travels into the granular layer and cannot be followed any farther in this sample.

The next figure shows another Golgi-impregnanted Lugaro cell. The dendrites are restricted to the region of Purkine cells bodies, and the axon spreads to the molecular and granular zones.

From Lugaro cells


The Lugaro cells axon contacts exclusively inhibitory interneurons, including stellate, basket, and Golgi cells. The parallel axon preferentially contacts stellate and basket cells and the transverse axon contacts Golgi cells. The Lugaro cell is a key interneuron in the cerebellum, because it interconnects many neurons located in all cortex layers. It samples information at the level of the Purkinje cell axon collaterals and distributes information to the molecular and granular layers of cerebellum.

Lugaro cell electrophysiology

Very little is known about the electrophysiology of Lugaro neurons, because Lugaro cells are normally silent in cerebellar slice preparations. It has been reported that Lugaro cells are sensitive to 5-HT, although the significance of this finding is unclear since the cerebellum has comparatively little 5-HT compared to other brain regions. Lugaro cell excitation and subsequent Golgi cell inhibition can be evoked by submicromolar concentrations of 5-HT. Application of 5-HT to Lugaro cells triggered IPSPs on Golgi cells. The excitation of Lugaro cells by 5-HT could be inhibited by 10 uM ketanserin, showing the involvement of 5-HT2A receptors.

From Lugaro cells


Because of the well-known organization of the cerebellar system, Lugaro cells may represent valuable cellular models to analyze the function of bipolar sensory neurons within the brain.


Reference

Laine J. and H. Axelrad. (1996). Morphology of the Golgi-impregnated Lugaro cell in the rat cerebellar cortex: a reappraisal with a description of its axon. J. Comp. Neurol. 375, 618-640.

Wednesday, June 11, 2008

Raphe neurons

The raphe neurons project axons to widespread areas of cortex. Numerous studies have shown that the raphe inhibits distant structures.

From Raphe neurons


The raphe nuclei are part of the reticular formation of the mesencephalon. There are 2 major clusters (blue) of 5-HT-synthesizing neurons, shown in the Figure below. There is also a group of 5-HT-containing neurons located on the ventral medulla (white asterisk).

From Raphe neurons


The two main groups of raphe neurons are referred to as the rostral and caudal groups. The rostral group of 5-HT neurons, localized in the pons and mesencephalon, contains the nucleus centralis superior and dorsal raphe nucleus (DRN), which supply most of the 5-HT to the forebrain. The rostral group ascends in the medial forebrain bundle to widespread areas of the diencephalon and telencephalon. Some of the targets of DRN axons include the medial prefrontal cortex, sensorimotor and associative parietal cortex, non-specific intrathalamic nuclei and midline nuclei of thalamus, striatum, and the mesencephalic reticular formation. The rostral-projecting DRN contains the largest aggregate of 5-HT-containing cells in the nervous system, and it has been the subject of a disproportionately large amount of research relative to the other raphe nuclei.

The caudal or inferior group of 5-HT-synthesizing neurons, localized in the medulla, contains nuclei which supply most of the 5-HT to the spinal cord. The axons of caudal 5-HT nuclei form a bulbospinal tract that descends in the lateral and ventral funiculi of spinal cord, and terminates in the substantia gelatinosa of spinal cord, a region involved in pain perception. Medullary 5-HT-containing neurons in the brain stem also project to the sympathetic outflow in the spinal cord, targeting the sympathetic intermediolateral cell column. Serotonin is involved in mediating inhibition of sympathetic activity, because lesions of 5-HT containing axons in the cervical spinal cord can abolish the inhibition of sympathetic discharge produced by raphe stimulation.

Afferents to the raphe neurons come from spinal cord, cerebellum, cortex, caudate nucleus, hypothalamus, and habenular nuclei. Raphe cells also receive afferent input from fluid-borne substances in the blood and cerebrospinal fluid. Raphe cell bodies and dendrites tend to cluster near blood vessels, branching off the vertebral and basilar arteries. Dendrites are the most commonly found profiles in the raphe nucleus.

The DRN is composed of dopaminergic and GABAergic neurons, not only serotonergic neurons. In some areas of the rat DRN, GABA and 5-HT coexist in the same neuron. The DRN displays immunoreactivity for GABA, tyrosine hydroxylase, substance P, calbindin, parvalbumin, and calretinin.

Why are the raphe neurons so great?

With far-reaching axons that can have a million or more synaptic contacts, and dendrites that sense body temperature, glucose, pH, and CO2 and O2 levels in nearby blood and CSF, the raphe neurons exert a powerful effect on widespread regions of the body. How do the raphe neurons accomplish this wide array of tasks? Serotonin-containing neurons have a historical role as some of the largest, most central neurons in the organism. These neurons are very active in DNA and protein synthesis, and build larger cell bodies and innervate larger postsynaptic target areas compared to most neurons. 

Some of the largest neurons in the snail and leech are 5-HT-containing giant neurons. The nuclei of the largest neurons of mature Aplysia contains 0.2 ug DNA, more than 200,000 times the haploid amount. What distinguishes neuronal giants from other cells is that their dendrites provide a large receptive area for synaptic input and their axons allow communication with target organs over great distances, consequently these neuronal giants are required to synthesize more DNA and RNA than other cells to maintain the structural integrity of their extensive processes. Neuronal giants require a large turnover of protein for enzymatic and structural function. Most, if not all, of this intense DNA and protein synthesis occurs in the cell body where large quantities of ribosomes surround the nucleus. It is thought that some neuronal giants are able to synthesize more DNA and RNA through polyploidy and polyteny.

Although they do not have exceptionally large cell bodies, raphe neurons may be able to sustain high levels of DNA synthesis through polyploidy. In a study of adult rabbit 5-HT neurons, approximately 10% of raphe magnus neurons had two nucleoli, as shown below. Cresyl violet staining revealed enlarged nuclei and minimal cytoplasm in raphe magnus cell bodies. The function of this high DNA content is unknown, but it might be related to endoreplication, e.g. replication of specific parts of the genome.
From Raphe neurons

The diagram below shows two large 5-HT-containing neurons in snail. This bilateral pair of serotonergic giant cells in Helix pomatia sends large axons to the esophagus and buccal ganglia and feeding musculature of the oral region. Giant neurons of the snail are involved in secretory processes and are more metabolically active than other neurons.

From Raphe neurons


The largest cells in the leech Hirudoo medicinalis nervous system are the colossal cells of Retzius, shown below. These cells survive well in culture and have been studied extensively. Retzius cells synthesize and contain 5-HT, and have an exceptionally large size and DNA content. Much of the secretion of 5-HT from Retzius cells is from the somatic release of neurotransmitter from the huge cell body, a process that involves dense core vesicles.
From Raphe neurons

It is known that Retzius cells contain a high amount of 5-HT because the cell bodies of dehydrated Retzius cells fluoresce strongly when exposed to formaldehyde vapor. Like raphe neurons, Retzius cells have gap junctions that electrically couple to other Retzius cells.

References

Jacobs B. L. and C. A. Fornal. (1999). Activity of serotonergic neurons in behaving animals. Neuropsychopharmacology. 21, 9S-15S.
Gillette R. (1991). On the Significance of Neuronal Giantism in Gastropods. Biol. Bull. 180, 234-240. doi:10.2307/1542393