Prenatal exposure to Benzo[a]pyrene causes learning and memory impairment and loss of neurons in hippocampus during development of wistar rats

Abstract

Animal studies demonstrate that exposure to benzo[a]pyrene, (B[a]P) is associated with developmental neurotoxicity. The neurotoxicity of B[a]P is proposed to arise from the genotoxicity leading to neuronal cell death. Hence, gestational exposure to B[a]P during foetal development is thought to affect the adult behaviour. To explore this, in the present study the neurotoxic effects of B[a]P dosage (thrice, 300μg/kg/BW/ day, each) after prenatal exposure were investigated. The pregnant Wistar rats were administered with B[a]P by intraperitonial (i.p.) from gestational days (GD14-17) with control group (i.e.,<0.1% DMSO) and a separate group of rats without any treatment taken as naive group. Behavior was assessed in the offspring at 6 weeks of age by using T-maze test and novel object recognition test. The histopathological analysis was carried out by haematoxylin and eosin (H&E) staining method. A significant increase in the time spent in left arm, and decreased percentage of spontaneous exploration was observed in B[a]P treated groups in comparison to naïve and control. Further, time taken to reach near the novel object was significantly decreased, with significant increase in spontaneous exploration time in the B[a]P treated Wistar rats suggesting that gestational exposure impairs learning and memory as well as explorative behavior of rats. Cytomorphometry analysis of hippocampus showed significant loss in number of neurons in B[a]P treated group as compared to naive and control. Taken together, these findings showed during development gestational B[a]P exposure exerts memory deficit at adulthood and neuronal loss in hippocampus indicating its influences on adolescence behavior of the next generation.