Effects of psychotropic drugs on hyperemotionality of rats with bilateral ablations of the olfactory bulbs and olfactory tubercles

Abstract

The effects of psychotropic drugs on hyperemotionality of the rat with lesions in the olfactory system, including the olfactory bulbs and olfactory tubercles (O.B.-O.T. rat), were investigated, and compared with the neurotoxic effects of these drugs measured on rotarod performance of the mice with bilateral olfactory bulb ablations (O.B. mice). Chlorpromazine, reserpine and meprobamate inhibited the hyperemotionality at doses close to their neurotoxic dose. Pentobarbital showed only a slight effect on the hyperemotionality at subhypnotic doses. Chlordiazepoxide, diazepam and haloperidol markedly inhibited the hyperemotionality at lower doses without causing neurotoxicity. Imipramine and amitriptyline selectively inhibited mouse-killing behavior (muricide) of the O.B.-O.T. rat without affecting the other hyperemotional responses to various stimuli, thus differing from tranquilizers. The mode of action of these drugs in the O.B.-O.T. rat was essentially the same as observed in either the O.B. and the septal rats. For evaluating the effects of psychotropic drugs, the O.B.-O.T. rats are superior to the O.B. and septal rats, as they share both offensive aggression of the O.B. rat and hyperreactivity of the septal rat, and furthermore they exhibited muricide in a much higher incidence soon after the brain lesions.