Prenatal maternal phenobarbital increases reactivity and retards habituation of mature offspring to environmental stimuli.

Adult female offspring of C57BL/6J mice injected daily with phenobarbital for the last third of pregnancy were more active than control offspring during a 3-min test period in an open field arena, thus confirming previous reports of lasting effects of prenatal exposure to phenobarbital. These offspring habituated less rapidly than control offspring to the open field and were more reactive to sudden changes in environmental stimuli. The behavioral changes were not accompanied by body or brain weight deficits. The maternal drug injections did not alter brain concentrations of dopamine or norepinephrine in the adult offspring or the degree of reduction in these transmitters produced by the synthesis inhibitors alpha-methyltyrosine. Although activity was reduced by the catecholamine synthesis inhibitor, the effect was similar by offspring of both drug-treated and control dams.