急性生理应激对大鼠的行为及脑神经颗粒素磷酸化水平的影响

The Effects of An Acute Physiological Stressor on Behaviors, Protein Levels and Phosphorylation of Neurogranin in Rats

突触特异性蛋白质在应激所致行为效应的中枢机制中的可能角色日益受到关注。神经颗粒素（Neurogranin，NG）是一种新发现的突触特异性蛋白质，主要分布在前额叶、杏仁核和海马区域，参与突触结构和功能可塑性机制，可能涉及到应激所致行为效应中枢机制。但是，关于NG、应激和行为之间的关系国内外尚缺乏系统的研究报道。本研究主要是探讨急性生理应激对大鼠行为和NG的作用，以及NG的变化与应激性行为效应之间的相互关系。以急性强迫性冷水游泳应激，建立生理应激动物模型。将40只雄性SD大鼠随机分为游泳应激组1（SS1，接受游泳应激和行为测试）、游泳应激组2（SS2，接受游泳应激而不接受行为测试）、正常对照组1（C1，接受行为测试）和正常对照组（C2，不给予任何处理）（n=10）。以旷场行为和高架十字迷宫任务来评定大鼠应激后的行为变化，Western blotting方法测定海马和前脑皮层中的NG含量和磷酸化水平。结果表明：应激后SS1组的呆滞行为增加，与C1组比较，差异有显著性， P<0.01；SS1组皮层的NG磷酸化水平增高，与C1组相比，差异具有显著性，P<0.01；前脑皮层的NG磷酸化水平与呆滞行为之间的相关达显著水平。提示该应激源能诱发动物明显的恐惧反应，呆滞行为是反映急性生理应激导致行为障碍的敏感的行为学指标，海马和前脑皮层均是对急性生理应激反应敏感的脑区。NG的磷酸化水平可能是反映急性生理应激所致行为障碍的一项新的生物学指标。

The possible role of brain-specific protein in mediating stress-induced behavioral disorder has gained more and more attention. Neurogranin is a brain-specific protein newly found，which is Ca2＋sensitive/calmodulin-binding protein kinase C substrate， and is involved in the process of signaling conduction and long-term potentiation. It is mainly distributed in the frontal cortex， hippocampus and amygdala of rodents that are considered essential components of neural circuitry mediating stress responses. NG knockout animals exhibited deficits in learning and memory. These results implied that NG might be a mediator between stress and behavior. Studies concerning the relations between neurogranin， stress and behavior can provide further information about the mechanisms underlying the effects of stress on behavior. The aim of the present study was to investigate the effects of acute physiological stress on behavior and protein levels of neurogranin in brain， and the correlation between protein levels of neurogranin and stress-induced behavioral changes. Forty rats were randomly divided into swimming stressed group 1 (SS1)， swimming stressed group 2 (SS2)， handled-control 1 (C1) and handled-control 2(C2)， with ten in each. The forced cold-water swimming was used as a physiological stressor. Behavioral changes in rats after stress were observed by open-field test and elevated plus maze task， and protein levels and phosphorylation of neurogranin of hippocampus and forebrain were determined by Western blotting. The results showed that freezing in open-field test in SS1 was more increased than that in C1 group (p