Morphology in hippocampal neurons and behavioral change in rats with sub-chronic exposure of benzo(a) pyrene

Objective To explore the effects of benzo(a)pyrene(BaP) exposure on spatial learning and memory abilities and ultramicrostructure of hippocampal neurons in rats.Methods Fifty healthy male SD rats were randomly divided into a control group,a solvent control group and three BaP-treated groups.The exposure groups were treated by intraperitoneal injection with 2.5,5,and 10 mg/kg BaP once a day,respectively.The rats in solvent control group received an equal volume of corn oil.The treatment was lasted for 30 days.The capability of learning and memory of the rats were measured by Morris water maze test.The specimens of hippocampus were sliced and the morphological changes were observed with transmission electron microscopy.Results The times of passing through the platform were 12.03±2.43,11.35±2.68,9.75±1.78,7.63±1.67,and 4.38±1.46 and the time(in second) of staying around the platform were 46.34±11.56,48.12±13.22,32.35±7.68,26.13±5.34,and 16.14±3.15,respectively,for the rats of blank control,solvent control,low-,moderate,and high-dose BaP treatment group.A significant impairment in Morris water maze performance among the BaP-treated rats was observed compared with the controls(P0.05).The results also showed that damages of ultramicrostructure of hippocampal neurons were significant in the BaP-treated groups compared with that of the controls.Conclusion BaP has neurobehavioral toxicity in rats.