EFFECTS OF PRENATAL EXPOSURE TO DIAZEPAM ON EXPLORATION BEHAVIOR AND LEARNING-RETENTION IN MICE

Diazepam (2 mg/kg, DZP) or placebo were administered by oral gavage th roughout gestation in 40 mice. The automatic hole board test for mice (Boissier and Simon) was used to measure the locomotor activity and th e number of holes explored by the offspring (mean age 30.6 days). Duri ng the first test, this number represents curiosity. Its progressive d ecrease when the test is repeated (4 times at 1-day intervals) is a co nsequence of learning retention. In the first test, neither curiosity nor activity were linked with the mother's treatment or sex. During th e next tests, there was no difference in locomotor activity between DZ P and placebo groups. However, the DZP exposed pups explored fewer hol es than controls. Although there was a tendency towards greater activi ty in the female group, the number of holes explored in the placebo gr oup was significantly higher in females than in males. Paradoxically, this difference in learning memory function which exists between contr ol males and females was not observed in the DZP group, corresponding to an impaired learning retention.