Effects of maternal absorption of phenobarbital upon rat offspring development and function.

Sixty Sprague-Dawley derived primaparous rats were administered Luminal (sodium phenobarbital) subcutaneously in doses of either 80 mg/kg, 40 mg/kg, or 0 mg/kg (saline) on Days 9-21 of gestation. The two drug groups delivered litters significantly later with evidence of increased resorption at the higher dose. The higher dose offspring were lighter in weight at birth and at adulthood, but not at weaning. The lower drug dose offspring were developmentally accelerated compared with the other two groups. Acquisition of a conditioned avoidance response (CAR) was negatively correlated with increased drug dose. In appetitive operant paradigms, saline offspring received more reinforcements on fixed ratio sequential schedules, and the lower drug dose offspring received significantly fewer reinforcements than either of the other two groups on an FR-concurrent schedule. Both groups of drug offspring were able to obtain their reinforcements with a lower expenditure of effort than the saline offspring. The higher drug dose offspring made significantly more incorrect (early and late) responses on a schedule which rewarded a delayed response (DRL).