Behavioural similarities between mother rats and benzodiazepine-treated non-maternal animals.

Mother rats nursing large litters are hyperphagic, aggressive towards conspecifics, and show less freezing behaviour than non-maternal animals. These naturally occurring adaptations resemble those elicited by benzodiazepine treatment in virgin rats, indicating a common neurochemical change in the brains of mother rats and benzodiazepine-treated virgins. In line with this hypothesis, it was found that three functional benzodiazepine antagonists (FG 7142, pentylenetetrazol, caffeine) decreased food intake, lowered aggression and strengthened freezing in lactating mother rats. These psychopharmacological observations support the idea that GABA neurotransmission is enhanced during motherhood in the rat.