恐惧应激对大鼠小肠促性腺激素释放激素受体的影响

目的：观察恐惧应激状态下SD大鼠小肠黏膜促性腺激素释放激素（GnRH）受体的分布和表达变化。方法：建立SD大鼠恐惧应激模型,分别取急性应激组（2~12 h）、慢性应激组（1 d~4周）和相应对照组的小肠。用免疫组化和Western blot法检测GnRH受体在各实验组大鼠小肠中的分布和表达变化。结果：免疫组化显示：急性应激组、慢性应激组和相应对照组的小肠黏膜层均呈GnRH受体免疫反应阳性,无明显差异。阳性反应物质定位于细胞膜和细胞质,细胞核呈阴性。Western blot结果表明：在急性应激状态下,GnRH受体表达有增多的趋势,但与相应对照组相比无显著性差异（P〉0.05）;慢性应激组与其相应对照组相比,GnRH受体表达明显增加（P〈0.05）。整个慢性应激过程中,GnRH受体表达增多持续1~4 d。1~3周时,GnRH受体表达降低,3~4周时又有所回升,并接近慢性应激相应对照组。结论：随着恐惧应激时间的延长,GnRH受体在小肠中表达增加。提示GnRH在恐惧应激中,对消化功能的影响具有潜在的生理调节功能。

Effect of threat stress on the GnRH receptor in the small intestine of Sprague-Dawley rats

Objective:To study the localization and the quantity of GnRH receptor expression in the small intestine of Sprague-Dawley(SD) rats under stress.Methods: The model of the treatment-stressed SD rat was established.Then the small intestines were taken from the rats in the acute stress group(2-12 h),chronic stress group(1 d-4 w)and the control group,respectively.The localization and the quantity of GnRH receptor expression in the small intestine were detected using immunohistochemistry and Western blotting.Results:Immunohistochemistry showed GnRH receptor immunoreactivity in the cells above the mucous layer in the small intestine of all the groups.The immunoreactive materials were distributed in the membrane and cytoplasm of all positive cells,but not in the nuclei.Meanwhile,Western blot showed that although the expression of the GnRH receptor tended to increase under acute stress,there were no significant differences between the acute stress and the control(P>0.05).However,compared with the control group,the expression of the GnRH receptor increased significantly in the chronic stress group(P<0.05),which reached the peak when stressed for 4 days,decreased from 4 d to 3 w,and increased again to get close to the control from 3 w to 4 w.Conclusion: The expression of the GnRH receptor increased with the time of threat stress,which suggests that the GnRH receptor could regulate the digestive function under stress.