HALLUCINOGENIC COMPOUNDS AND SWIMMING RESPONSE

¹ Stanford Research Institute, Menlo Park, California

The effects of several hallucinogenic compounds and their nonhallucinogenic analogs were evaluated in an underwater swim alley. Rats were submerged and forced to swim underwater through plastic tubes 3.47 m long in order to escape at the other end of the tubes. All of the compounds tested significantly increased the starting latency but only d-amphetamine significantly increased swimming time. The peak effect time for d-lysergic acid diethylamide (LSD-25) and three amphetamine derivatives on latency was 20 mm after the i.p. injection; that for 2-brom-lysergic acid diethylamide (BOL-148) was 40 min. Dose-response curves indicated that the increase in latency was a function of dose. The ED50's for LSD-25, BOL-148, 2,4,5-trimethoxy-amphetamine (TMA-2) hydrochloride, 3,4,5-trimethoxyamphetamine (TMA) hydrochloride, d-amphetamine hydrochloride and 4,5,6-trimethoxyamphetamine (TMA-3) hydrochloride were 1.9, 11.0, 15.0, 31.0, 36.5 and 77.0 µmol/kg, respectively. An analysis of relative effectiveness indicated that LSD-25, TMA-2 and TMA (in descending order) were significantly more effective than their respective nonhallucinogenic analogs.