Behavioral activation in infant rats: Pharmacological evidence for dopaminergic mediation

Abstract

During the first postnatal week, rat pups exhibit diffuse, perseverative behaviors in response to many environmental stimuli, including intraoral milk infusions. This phenomenon has been referred to as behavioral activation (Hall, 1979a, 1979b). In this paper, several lines of evidence that implicate central dopaminergic systems as mediators of behavioral activation aire presented. First, stimulation of the dopamine system by L-dopa or apomorphine resulted in age-dependent behavioral activation similar to that elicited by milk infusions. Second, the magnitude of the activating effect elicited by L-dopa was influenced by the contextual variables of room temperature and deprivation in the same manner as is milk-induced activation. Finally, blocking the dopamine system with haloperidol prevented both milk infusions and L-dopa from evoking behavioral activation in young pups. © 1987, Psychonomic Society, Inc.. All rights reserved.