Effect of benzo[a]pyrene on learning behaviors and NOS and NO in hippocampus of rats.

[Objective] To probe the effect and its possible mechanism of benzo [a] pyrene(BaP) exposure on the capability of learning and memory in rats.[Methods] Forty Wistar growing rats were randomly divided into five groups:blank control group,rats in solvent group were injected vegetable oil and those in experimental groups were peritoneal injected different doses of B(a) P(1mg /kg,2.5mg /kg,6.25mg /kg) every day for 13 weeks.The capability of learning and memory in rats were measured by means of Morris water maze test,the NOS activity and NO content in hippocampus of rats were tested.[Results] In training of Morris water maze,the mean escape latency of rats in the BaP groups were longer than that in the control groups and the frequency of last bestride platform in the experimental groups were less than that in the control groups(P ﹤ 0.05).The NOS activity and NO content in hippocampus in BaP groups were also significantly lower than that in control groups.[Conclusion] Long-time exposure BaP could decrease the capability of learning and memory of rat.BaP may inhibit the NOS activity to induce of NO content in hippocampus,which damages the induction and maintenance of LTP.