单眼形觉剥夺大鼠视皮层α-氨基-3-羟基-5-甲基异恶唑-4-丙酸受体GluR2的表达及其变化对微小兴奋性突触后电流的影响

The changes of AMPA receptors subunit GluR2 and mEPSCs in visual cortex of monocular deprivation rats

目的观察单眼形觉剥夺大鼠视皮层中α-氨基-3-羟基-5-甲基异恶唑-4-丙酸（alphaamino-3-hydroxy-5-methyl-4-isoxazolepropionic acid，AMPA）受体的表达变化及其对突触后电流mEPSCs的影响，为研究其在视觉发育可塑性中的作用及机制做准备。方法实验研究。取14d龄健康Wistar大鼠40只，随机分为2组（Ⅰ、Ⅱ），每组20只，再随机分成A、B两组，每组10只。对实验组（I组）行单眼形觉剥夺，正常饲养1周后对IA组及ⅡA组常规心脏灌注、固定、切取视皮层，对组织切片行免疫组织化学法显色，显微镜观察AMPA受体GluR2的表达情况并进行图像分析，同时对ⅠB组及ⅡB组应用脑片膜片钳全细胞记录技术，获得大鼠视皮层神经元的细胞内微电极记录，记录突触后电流mEPSCs的变化。结果AMPA受体GluR2在正常发育组视皮层中的表达较单眼形觉剥夺组视皮层中的表达水平高，差异有统计学意义（P〈0．01）。脑片膜片钳记录结果显示：AMPA受体介导的初级视皮层2／3层的锥体神经元的微小突触后兴奋性电流（mEPSCs）幅值增高。结论大鼠出生后视皮层AMPA受体GluR2的水平受视觉刺激而发生变化，且其变化影响微小突触后兴奋性电流，提示其对出生后大鼠的视觉发育有着重要的生理作用。

Objective To observe the change of expression in quantity of AMPA receptor subunit GluR2 and mEPSCs from monocular deprivated rats. The preparative work was conducted for the further study on mechanism involved in regulation and control of the visual development plasticity. Methods It was an experimental study. Forty 14 d healthy Wistar rats were divided into two groups randomly; twenty in each group which were divided into two groups （ Ⅰ , Ⅱ ） and deprivated monocular in experiment group （group Ⅰ ） ,and then were killed at a week later. For Ⅰ A and ⅡA 5μm thick section was cut from tissue of visual cortex in coronary side, then the expression of GluR2 was observed by microscope and image analyze of GluR2 was conducted after immunohistochemical staining; for Ⅰ B and Ⅱ B,mEPSCs was investigated which was used Voltage-clamp technique with whole-cell mode. Result The level of GIuR2 in visual cortex of normal rats was higher than experiment group. The mean amplitude and frequency of mEPSCs increased in the deprivated monocular group. Conclusions The level of GluR2 has changed association with the visual stimulation,which suggests that GluR2 should have the important physiological function on the postnatal development of visual system of rats.