NEUROPHARMACOLOGICAL REGULATION OF MOUSE KILLING BY RATS

The literature concerning the neuropharmacology of mouse killing was reviewed with attention to the behavioral specificity of the response. Increases in monoamine activity (serotonin or catecholamine) result in a behaviorally specific blockade of the killing response by natural killers. Large decreases in brain serotonin by peripheral or central drug treatment or by central brain lesions induce killing in both naive rats and experienced nonkiller rats. Moreover, the mode of depletion is important and, with certain manipulations, the inductions of killing is accompanied by increases in general irritability and by an alteration of the stereotypic killing pattern. Large depletions of the catecholamines either by synthesis inhibition or by neurotoxic drug action do not induce killing in the majority of nonkillers. Peripherally administered cholinergic agonists and antagonists, with 2 exceptions, are ineffective in inducing killing in nonkillers or in blocking killing by killers. Evidence for centrally elicited stereotyped killing by cholinergic stimulation of brain tissue is not consistent, but cholinergic systems are implicated in the facilitating of killing by spontaneous killers.