Perinatal diazepam exposure: behavioral and neurochemical consequences.

In the present study the effects of perinatal diazepam (DZP) exposure on behavior and benzodiazepine binding site characteristics in offspring were investigated. Pregnant F344 rats were treated during the last trimester of gestation with vehicle or diazepam (3 mg/kg, 5 mg/kg, or 10 mg/kg). Lactating dams were similarly treated on postnatal days 1-7. Both prenatal and postnatal exposure to diazepam resulted in significant effects on the acquisition and extinction of active avoidance behavior measured postweaning. The number of trials to extinction of one-way active avoidance behavior was significantly greater in offspring exposed gestationally to 3 mg/kg and 10 mg/kg diazepam and postnatally to 10 mg/kg diazepam. The mean response latencies for all diazepam treated groups were significantly shorter than those of the vehicle treated rats during the first 15 trials under extinction conditions. In contrast, neither gestational nor postnatal diazepam exposure significantly affected either acquisition or retention of a passive avoidance task. In addition, the binding affinity between the benzodiazepine type I selective ligand, CL218,872, and cortical membranes, as well as the degree to which GABA potentiated 3H-flunitrazepam were significantly altered by perinatal diazepam exposure. No treatment altered the approximate number of benzodiazepine binding sites in either the cortex, hippocampus, or cerebellum. The results of this study further support diazepam as a behavioral teratogen and give new evidence for neurochemical effects following gestational as well as postnatal diazepam exposure.