Central antiserotonin action of fluperlapine.

The effect of fluperlapine--a new nonclassical neuroleptic--on the central serotoninergic system was studied. Fluperlapine antagonizes the head-twitch response induced by 5-hydroxytryptophan in mice and rats (the ED50 values are 0.3 mg/kg ip and 0.89 mg/kg ip respectively), counteracts forepaw clonic convulsions and tremor induced by tryptamine in rats (ED50 = 9.0 mg/kg ip and 7.5 mg/kg ip respectively), and abolishes hyperthermia induced by fenfluramine. In the flexor reflex preparation in spinal rats fluperlapine depresses the reflex only when given in higher doses. The drug given in low doses abolishes the stimulation of the flexor reflex evoked by quipazine and LSD (serotonin agonists) but not by clonidine (noradrenaline agonist). Higher doses of fluperlapine antagonise also the stimulatory effect of clonidine. Our findings demonstrate that fluperlapine shows potent central antiserotonin activity.