苯并[a]芘对大鼠学习记忆能力及氨基酸类神经递质的影响

[目的]探讨苯并[a]芘(B[a]P)对大鼠学习记忆能力的影响及机制。[方法]40只Wistar大鼠随机分为5组:空白对照组、溶剂对照组和3个染毒组(分别为6.25、2.5和1mg/kg体重),连续腹腔染毒B[a]P13周(90d)。染毒结束后用Morris水迷宫测定大鼠的空间学习记忆能力,用免疫组化法观察其大脑皮层、海马内γ-氨基丁酸(GABA)及谷氨酸(Glu)阳性神经元表达。[结果]在Morris水迷宫试验中,高、中剂量组寻找平台的潜伏期较对照组延长(P﹤0.05),末次跨平台次数和在目标区域游泳时间所占比例较对照组明显减少(P﹤0.05),各暴露组Glu、GABA阳性平均光密度与对照组比较差异有统计学意义(P﹤0.05)。[结论]苯并[a]芘可能通过影响大鼠海马和大脑皮质Glu和GABA含量,使大鼠学习记忆能力降低。

EFFECT OF BENZO[a]PYRENE ON LEARNING AND MEMORY BEHAVIORS AND THE EXPRESSION OF AMINOACID NEUROTRANSMITTERS IN RATS

[Objective]To probe the effect and possible mechanism of Benzo[a]pyrene(B[a]P)exposure on the capability of learning and memory in rats.[Methods]Forty weaned Wistar rats were randomly divided into 5 groups,including a control group,a solvent control group and three B[a]P-treated groups,which were peritoneal injected different doses of B[a]P every day for 13 weeks.The capability of learning and memory in rats were measured by means of Morris water maze test,and immunohistochemical method was used to observe the expressions of γ-aminobutyric acid(GABA),gliutamic acid(Glu)positive neurons in cerebral cortex and hippocampus.[Results]In training of Morris water maze,the mean escape latency of rats in high,medium dose group were longer than that in the control group,the frequency of crossing platform and the time of swimming in the target area of rats in high,medium dose group were less than that in the control group.The positive average optical densities of Glu,GABA in exposed group were significantly different from that in the control group.[Conclusion]Exposure B[a]P could reduce the capability of learning and memory in rats through reducing the content of Glu,GABA in hippocampus and cerebral cortex.