Effects of Psychotropic Drugs on Emotional Behavior in Rats with Limbic Lesions, with Special Reference to Olfactory Bulb Ablations

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Abstract
Summary: The effects of various psychotropic drugs on emotional behavior of the rats with bilateral ablations of the olfactory bulb (O.B. rat) were compared with those in the intact as well as in the rats with septal or amygdaloid lesions.1. Chlorpromazine markedly reduced both ambulation and rearing in intact as well as limbic lesioned rats. The hyper‐motional responses to all kinds of stimuli were suppressed by this drug in the O.B. and septal rats.2. Diazepam also suppressed the hyper‐emotional responses of the O.B. and septal rats, but on the contrary to chlorpromazine, it increased ambulation whereas it decreased rearing in the intact and amygdaloid rats. Diazepam, however, greatly decreased both ambulation and rearing of the O.B. and septal rats.3. Pentobarbital had no significant effect on the hyperemotionality of the O.B. and septal rats in subhypnotic doses. Pentobarbital, like diazepam, increased ambulation but decreased rearing of the intact rats, although it markedly reduced both ambulation and rearing of the septal rat, and showed less significant effects on ambulation of the O.B. and amygdaloid rats.4. Imipramine, similarly to chlorpromazine, decreased both ambulation and rearing in each group of the rats. Imipramine selectively blocked mouse‐killing behavior without affecting the other hyperemotional responses to stimuli of the O.B. rats. These properties were shared with amitriptyline and nialamide.5. It is suggested that the analyses of drug effects on emotional behaviors of the rats with various limbic lesions are helpful to distinguish the mode of action of various psychotropic agents. (This study was supported in part by the grant for the research of science from the Department of Education of the Government of Japan.)