Drugs that antagonize limb flick behavior induced by D-lysergic acid diethylamide (LSD) in cats.

In cats observed in their home cages limb flicks (LF) are a sensitive measure of the behavioral effects of LSD. LF induced by LSD (50 microgram/kg) were blocked by dextrorphan (0.6 mg/kg), dextromethorphan (0.6 mg/kg), and imipramine (5 mg/kg) at doses that did not produce ataxia or sleep. Levorphanol (0.6 mg/kg), a narcotic that is a congener of dextrorphan, did not block LF induced by LSD possibly because it produced an excitatory effect when given alone. Pentobarbital at low doses (2 and 4 mg/kg) increased the number of LF induced by LSD but at a high dose (8 mg/kg) decreased LF induced by LSD either by producing ataxia, so the cats tended to remain immobile, or by producing sleep. Chlorpromazine (CPZ) at three doses (2, 4, and 8 mg/kg) attenuated the effects of LSD on LF, but did not block LF as completely as the above three blocking drugs, and produced ataxia and sleep.