RESUMEN
Experiments were carried out on male Wistar rats after development of defensive conditioned relex during 6 weeks of training. In one series of experiments chlorpromazine, haloperidol, pimozide or fluspirilene were used in doses of 0.05, 0.5 and 5.0 mg/kg intraperitoneally. In another series of experiments nialamide was given intraperitoneally in a dose of 140 mg/kg 16--18 hours before administration of one of these neuroleptics. A delay in the time of appearance of the defensive conditioned refex was observed after administration of neuroleptics in all animals. In some rats neuroleptics caused complete disappearance of the conditioned refex as well as the defensive unconditioned refex. Previous inhibition of monoamine oxidase activity obtained with nialamide increased evidently the inhibitory effect of the studied neuroleptics on the appearance of defensive conditioned reflex.