大鼠脊髓后角内5型代谢型谷氨酸受体与C纤维的关系——免疫组织化学及电镜研究

THE RELATIONSHIP BETWEEN mGluR5 AND C-FIBER IN THE RAT SPINAL DORSAL HORN——A IMMUNOHISTOCHEMICAL STUDY AT THE LEVEL OF LIGHT AND ELECTRON MICROSCOPY

目的 揭示大鼠脊髓后角内 5型代谢型谷氨酸受体 (mGluR5 )与一级传入C纤维的关系。 方法 在大鼠单侧足底注射福尔马林作为疼痛刺激 ,应用免疫组织化学技术光镜下观察疼痛对脊髓后角内mGluR5的影响 ;在大鼠蛛网膜下腔注射辣椒素 ,以毁损C纤维 ,用免疫电镜技术观察大鼠脊髓后角浅层内mGluR5阳性结构与C纤维间的超微结构关系。 结果 脊髓后角疼痛刺激侧Ⅰ～Ⅱ层内mGluR5免疫反应性较对照侧明显增强 ;在蛛网膜下腔注射辣椒素的大鼠 ,电镜下可见其后角浅层内大量变性的C纤维轴突终末与 1至多个含mGluR5的树突形成突触联系。 结论 提示脊髓后角浅层内mGluR5主要作为突触后受体参与介导和调节C纤维内对伤害性信息的传入。

Objective To reveal the relationship between metabortropic glutamate receptor 5(mGluR5) and primary afferent C\|fiber in the dorsal horn of the rat spinal cord. Methods Pain stimulation was induced by injection of formalin into foodpad of the rats,the influence of pain on the immunoreactivity of mGluR5 in the dorsal horn of the spinal cord was observed by using immunohistochemistry.Capsaicin was injected into the subarachnoid space of the rat to cause degeneration of C\|fiber. Immunoelectron microscope was used to label mGluR5\|containing structures,and to examine the ultrastructural relationship between mGluR5 posivtive structures and C\|fiber in the laminae Ⅰ\|Ⅱ of rat spinal dorsal horn. Results On the side of pain stimulation,immunoreactivity of mGluR5 was significantly enhanced in the laminae Ⅰ\|Ⅱ of the spinal dorsal horn.In the dorsal horn of the rat spinal cord treated with capsaicin,a lot of degenerated axonal terminals of C\|fibers were found under electron microscope; these degenerated terminals formed synapses with one or several mGluR5 positive dendrites.Conclusion\ It was suggested,as a postsynaptic receptor,mGluR5 in superficial laminae of the spinal dorsal horn might be mainly involved in transmission and modulation of primary afferent of nociception.\;[