ROLE OF 5-HYDROXYTRYPTAMINE RECEPTOR SUBTYPES IN THE 1-[3-(TRIFLUOROMETHYL)PHENYL] PIPERAZINE-INDUCED INCREASE IN THRESHOLD FOR MAXIMAL ELECTROCONVULSIONS IN MICE

The effect of 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), a 5-hydroxytryptamine (5-HT) receptor agonist, on the threshold for maximal electroconvulsions was studied in mice. TFMPP in intraperitoneal (i.p.) doses of 10, 20 and 40 mg/kg increased the convulsive threshold (the amperage necessary to produce the hindleg tonic extensor component of seizures in 50% of animals) by 28, 60, and 85%, respectively. The effect of TFMPP (20 mg/kg) was dose-dependently blocked by 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine (NAN-190), prazosin, spiperone, mesulergine, ketanserin, and ritanserin. On the other hand, pindolol and cyanopindolol had no effect on the convulsive threshold increased by TFMPP. The results indicate that the TFMPP-induced decrease in the susceptibility to seizures is connected to stimulation of 5-HT2 or of both 5-HT1C and 5-HT2 receptors. Moreover, alpha(1)-adrenoceptors also appear to be engaged in this effect.