Effects of bicuculline infusions in the ventromedial hypothalamus and amygdaloid complex on food intake and affective behavior in mother rats.

The mother rat is hyperphagic, aggressive toward other adults, and less fearful than non-maternal rats. The present experiments were conducted to examine whether GABAergic (gamma-aminobutyric acid) mechanisms in the ventromedial hypothalamus and amygdala participate in the control of these behavioral changes. Unilateral infusions of the GABA receptor blocker bicuculline (60 ng/0.5 microliter) into the ventromedial hypothalamus depressed food intake and lowered aggression. Similar infusions into the amygdaloid complex did not affect eating, but they did reduce aggressive behavior. Freezing behavior, a natural fear response, was not affected by the hypothalamic or the amygdaloid bicuculline infusions. These data support previous evidence suggesting a role for GABA in the regulation of postpartum changes in food intake and affective behavior.