中文摘要：

目的 探讨不同剂量苯并（a）芘[B（a）P]对断乳大鼠学习记忆能力的影响及其机制.方法 将40只SD断乳大鼠（28d）随机分为5组,空白对照组、溶剂对照组、3个染毒组（浓度分别为5,10和20mg/kg体质量）,隔日腹腔染毒30d.染毒结束后用Morris水迷宫试验观察,免疫组化法测定海马组织中N-甲基-D天门冬氨酸受体NR2B亚基（NMDAR2B）和脑源性生长因子（BDNF）含量.结果 Morris水迷宫试验结果显示,随B（a）P染毒剂量的增加,逃避潜伏期呈递减趋势,高剂量组[（62.78 ±47.25）s]与对照组[（40.60 4-38.79）s]相比,差异有统计学意义（P〈0.01）;跨台次数随染毒剂量的增加逐渐减少,高剂量组[（4.33 ± 2.08）次]与对照组[（11.25 ± 2.63）次]相比.差异有统计学意义（P＜0.05）;随染毒剂量增加,海马区NMDAR2B灰度值呈递减趋势,高剂量组（150.38 ± 15.34）与对照组（162.23±6.56）相比,差异有统计学意义（P＜0.05）;BDNF灰度值除低剂量组外呈递减趋势,高剂量组（141.83 ±13.37）与对照组（163.13±8.09）、低剂量组（164.56±9.10）相比均差异有统计学意义（P＜0.05）.结论 亚急性B（a）P暴露可降低断乳大鼠空间学习记忆能力,其机制可能与B（a）P影响海马NMDAR2B和BDNF的表达有关.

英文摘要：

Objective To investigate the changes and mechanism of learning and memory in rats by different doses of benzo （a） pyrene （B（a）P）. Methods Forty weaned rats （28 days） were randomly divided into control group （NS）, solvent group （ vegetable oil） and three B （a） P dosage groups （the doses were 5,10 and 20 mg / kg body weight respectively ）. And all rats were administrated intraperitoneally every other day to one month. The capability of learning and memory in rats were measured by Morris water maze test, and the brain-derived neurotrophic factor （ BDNF） and NMDAR2B content in hippocampus were tested by immunohistochemistry. Results In training of Morris water maze,the average escape latency was extended gradually with increasing dose, and there was a statistically significant difference between high-dose group（（62. 78 ±47. 25 ）s） and the control group（（40.60±38.79）s）（P〈 0.01）. Compared with the control group（11.25 ±2.63）, the number of crossplatform of high-dose group（4.33 ±2.08） was statistically reduced （P〈0.05）. B（a）P at 10 and 20 mg/kg decreased NMDAR2B and BDNF expression in hippocampus of rats in immunohistochemistry. The level of NMDAR2B was （162.23 ±6.56） in the high-dose group and （150.38 ± 15.34） in the control group（P〈0.05）;the expression level of BDNF was （163. 13 ± 8.09） in the high-dose group and （141.83 ± 13.37） in the control group（P〈 0.05）. Conclusion Subacute B（a）P exposure can reduce spatial learning and memory in weaning rats, it may be related to decreased levels of NMDAR2B and BDNF in hippocampus.