Acute and chronic effects of LSD and 5-MeODMT on raphe-evoked dorsal root potentials in the cat.

In cats, a single injection of LSD increased the dorsal root potential evoked by stimulating the nucleus raphe magnus, while a single injection of 5-MeODMT decreased it. The dose and time course of these electrophysiological changes matched the drugs' known behavioral effects. After four daily LSD injections, complete tolerance developed to LSD's potentiating effect, but the same pretreatment with 5-MeODMT did not alter its acute inhibitory effect. These results parallel the development of behavioral tolerance to LSD and 5-MeODMT, suggesting this system may serve as an electrophysiological model for studying these drugs.

Study at a glance

Abstract

Both acute and chronic effects of lysergic acid diethylamide (LSD) and 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) on the dorsal root potential (DRP), evoked by stimulation of the nucleus raphe magnus of the cat, were examined. Single injections of LSD potentiated while those of 5-MeODMT inhibited the raphe-evoked DRP. The electrophysiologic response produced by each drug correlates well in dosage and time-course with their reported behavioral effects. Following four consecutive daily injections of LSD, complete tolerance developed to the potentiating effect of LSD on this potential. A similar pretreatment schedule with 5-MeODMT failed to alter its acute inhibitory effect on the DRP. These results correlate well with the development of tolerance to the behavioral effects of LSD and 5-MeODMT. This system may thus provide a unique electrophysiological model to examine the effects of these drugs.