Shock-induced aggression and pain sensitivity in the rat: Catecholamine involvement in the corticomedial amygdala

Abstract

The possible role of amygdaloid catecholamines in the control of shock-induced aggression and pain sensitivity in the rat was investigated. Bilateral microinjections of chlorpromazine into the corticomedial amygdala resulted in decreased fighting and decreased sensitivity to the shock stimulus. Further analysis of this effect, using specific adrenergic antagonists, revealed that neither a- nor Padrenergic systems appeared to be responsible for the behavioral effect of chlorpromazine. Injections of haloperidol into the same region, however, yielded a reduction similar to that produced by chlorpromazine, while dopamine injections resulted in significant elevations in both fighting and pain sensitivity. No effect on any of these behavioral measures was obtained following injection of any of the agents into the basolateral amygdala. These results suggest that the observed effect of catecholamine injections in the corticomedial amygdala is related to changes in pain sensitivity mediated by dopamine.