LONG-TERM EFFECTS OF POSTNATAL MANIPULATION ON EMOTIONALITY ARE PREVENTED BY MATERNAL ANXIOLYTIC TREATMENT IN MICE

This study investigated the role of maternal behavior on the long-term effects of postnatal manipulation (15 milt of daily separation from t he dam and exposure to clean bedding from Day 1 to Day 14 of postnatal life) on emotionality in the mouse. Mothers were treated with an anti anxiety agent (Chlordiazepoxide: 5 mg/kg), daily upon removal of the l itter from the nest. Emotionality in adult off spring was tested in th e elevated plus maze. Mice manipulated during postnatal development we re more explorative and less anxious than unhandled mice, but this eff ect was not observable in the offspring of Chlordiazepoxide-treated da ms. No effect of maternal Chlordiazepoxide was observed in unhandled o ffspring. The pharmacological treatment of the mother did not affect e ither pups' ultrasonic calling during separation, or maternal behavior -far apart from the daily manipulation sessions. By contrast, Chlordia zepoxide-treated dams were less responsive toward pups upon reunion fo llowing daily separation. This alteration of dams' behavior-was not re lated to alterations in the amount of ultrasonic calls emitted by pups during reunion. Finally, when dams were daily injected with Chlordiaz epoxide far apart from pups' removal, the pharmacological treatment wa s devoid of effects. These results support the view that the mother-in fant inter-action which follows separation plays a major role in deter mining the effects of postnatal manipulations on adult emotionality. ( C) 1998 John Wiley & Sons, Inc.