Dopaminergic facilitation of recovery from amygdaloid lesions which affect hypothalamic defensive attack in cats

Influence of dopamine agonists, methamphetamine (MAT, 1 mg/kg, i.p.) and apomorphine (APO, 1 mg/kg, i.p.), on the effects of amygdaloid lesions on thresholds for the defensive attack behavior elicited by electrical stimulation of the ventromedial hypothalamic nucleus was studied in cats. The thresholds were measured in two situations, one with provocation by a human and the other without provocation. Electrolytic lesions of the basolateral part of the amygdala attenuated markedly facilitatory influences of the visual provocation on the thresholds, but subsequent administration of MAT or APO rapidly abolished the effects of the lesions. The effects of MAT lasted for at least 3.5 h while the effects of APO were of shorter duration. The results were discussed from the viewpoint of possible rapid compensation by the remaining intact tissue of the amygdala which was produced by excessive dopaminergic inputs to it.