Effects of various psychotropic drugs on self-stimulation behavior in the rat

Effects of various psychotropic drugs on tegmental and hypothalamic self-stimulation behavior in rats with chronically implanted electrodes in the brain were studied. Effects of electrical stimulation in several brain structures on self-stimulation behavior and influences of drugs on the stimulation effect were also investigated. The hypothalamic self-stimulation behavior was more markedly inhibited by chlorpromazine than the tegmental self-stimulation, whereas the latter was more strongly inhibited by diazepam. The effects of pentobarbital on the self-stimulation behavior were similar to those of diazepam. Methamphetamine facilitated both the tegmental and hypothalamic self-stimulation behavior. Suppressive effect of hypothalamic stimulation on the tegmental self-stimulation behavior was inhibited by chlorpromazine, while those of amygdaloid and septal stimulation were augmented. All the effects of hypothalamic, amygdaloid and septal stimulation on the tegmental self-stimulation behavior were inhibited by diazepam and pentobarbital, while these were facilitated by methamphetamine. Suppressive effects of tegmental, amygdaloid and septal stimulation on the hypothalamic self-stimulation behavior were all facilitated by both chlorpromazine and methamphetamine. The effects of amygdaloid and septal stimulation on this behavior were inhibited by diazepam and pentobarbital, while those of tegmental stimulation were enhanced. The effects of imipramine, in all experiments, were variable in each rat and not significant.