Sunday, May 24, 2009

LSD affects spinal cord activity in salamander

The behavior of fish is altered in a characteristic way when LSD is dissolved in the tank water. Instead of swimming around the tank, the fish hold still at the surface of the water. Likewise, salamanders exhibit statue-like postures and slow movements when injected abdominally with 0.7-0.8 mg/g LSD.


Rather large doses of LSD were used in these studies. Unless a mistake was made reporting the units, the dose given to salamanders was 0.7 mg/g of body weight, or 700,000 ug/kg. Typically, 25 ug/kg in cat or 100 ug in a person of average weight 85 kg (1.1 ug/kg) is all that is needed to elicit an LSD reaction. During the peak of drug action the salamander moved slowly and allowed its limbs to be moved by researchers. Peters wrote,
“Within 5 to 15 minutes after the injection of LSD-25 the salamander, when placed in water, shows disturbances of equilibrium during which the animal slowly writhes, comes to rest on its side, back, or belly, and assumes statue-like postures representing some stage in standing or walking. These floating postures are interrupted by slow movements of trunk or limbs as if the salamander were attempting to maintain its balance. The trunk and limbs are not limp, but have the firmness of soft wax, so that the animal allows itself to be moved passively, especially in water. During this phase of drug action, tactile stimuli applied to the tip of the tail are followed by ambiguous results, i.e. they may evoke a prompt escaping reaction as vigorous as that of an untreated animal, or a slow response delayed 5 to 10 seconds, or no response at all.” (Peters,J.J. 1956)

EEGs were recorded from the brain and spinal cord of salamander. Activity at the electrode over the brain was somewhat unchanged by LSD, but the electrode over spinal cord showed much more high voltage activity compared to the untreated condition. Spinal cord EEGs showed a sustained discharge of waves of high frequency and amplitude (figure below), even though the salamander appeared quiet and motionless. The results suggest a more pronounced drug effect on electrical activity in the spinal cord rather than the brain.


The powerful mental effects of LSD have led many researchers to suspect that LSD affects firing of neurons of the brain, but in the case of salamander the electrical activity of spinal cord was specifically affected. It may be important to consider the hypothesis that LSD does not necessarily exert its effects on higher order centers of the brain.


Reference

PETERS J. J. and A. R. VONDERAHE (1956). Behavior of the salamander under the influence of LSD-25 and Frenquel, and accompanying electrical activity of brain and spinal cord. The Journal of Nervous and Mental Disease 124, 69-73.