Phenobarbital during pregnancy alters operant behavior of offspring in C57BL/6J mice.

Offspring of C57BL/6J injected daily with phenobarbital for the last third of pregnancy responded less than control animals when maintained on various fixed ratio schedules of reinforcement. The response decrement became more pronounced as the schedule demands were increased and was noted in offspring of both sexes. The higest dose (80 mg/kg) was less effective than the 2 lower doses (20 mg and 40 mg/kg) in producing the decrement which may reflect a selection factor due to high neonatal mortality previously reported at this dose. The study provides no evidence of the mechanism mediating the long term behavioral abnormality but does clearly extend the finding of such changes to doses which do not produce increased neonatal mortality or noticeable morphological changes.