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目的:探讨Y迷宫训练后大鼠脑内基质金属蛋白酶-9(MMP-9)表达及其在海马依赖的学习记忆中的作用。方法:3月龄雄性SD大鼠,随机分成对照组(n=12)和Y迷宫训练组(n=60),后者又根据训练天数和处死时间分成5个亚组。计算大鼠在Y迷宫训练中的连续正确反应次数,观察其学习能力;用Westernblot检测各组大鼠不同脑区MMP-9前体蛋白(proMMP-9)和活性形式(actMMP-9)的蛋白表达,用免疫组化学和RT-PCR分别检测海马区MMP-9蛋白和mRNA的表达。探讨MMP-9表达与其学习能力的相关性。结果:①Y迷宫训练早期,大鼠海马区出现actMMP-9蛋白水平一过性增加,同时其MMP-9mRNA表达也相应升高;而额叶区未出现类似变化。②Y迷宫第1天训练后4h大鼠海马区actMMP-9表达水平与其第1天训练成绩(平均连续正确反应次数)呈正相关(P<0.05)。结论:actMMP-9可能参与了大鼠Y迷宫的学习过程。
Objective: To investigate the expression of matrix metalloproteinase-9 (MMP-9) in rat brain after Y maze training and its role in hippocampus-dependent learning and memory. Methods: Three-month-old male Sprague-Dawley rats were randomly divided into control group (n = 12) and Y-maze training group (n = 60), which were divided into five subgroups according to training days and time to death. The number of continuous and correct reaction in Y maze training was calculated and the learning ability was observed. Western blot was used to detect the protein expression of proMMP-9 and actMMP-9 in different brain regions of rats The protein and mRNA expression of MMP-9 in hippocampus were detected by immunohistochemistry and RT-PCR respectively. To investigate the relationship between MMP-9 expression and learning ability. Results: ① In the early phase of Y maze training, the level of actMMP-9 protein in rat hippocampus increased transiently and the expression of MMP-9 increased correspondingly; however, similar changes were not observed in frontal lobes. ② The expression level of actMMP-9 in hippocampus of rats on day 1 of Y maze was positively correlated with the training results on day 1 (mean continuous correct response times) (P <0.05). Conclusion: actMMP-9 may be involved in the learning process of rat Y-maze.