电针足三里穴对内脏痛大鼠腰髓神经元胶质细胞内P2X4受体表达和超微结构的影响

Effects of Electro-acupuncture at Zusanli Point on the Expression of P2X4 Receptors as well as Neurons and Glia Cells Ultrastructure of Lumbar Spinal Cord in Visceral Pain Rats induced by Colon-rectum Distention

目的:观察电针足三里穴对直结肠扩张性内脏痛模型大鼠腰髓背角内P2X4受体表达及神经元和胶质细胞形态学超微结构关系。方法:18只雄性SD大鼠随机分为空白对照组、结直肠扩张内脏痛模型组(内脏痛组)、电针足三里穴后结直肠扩张内脏痛模型组(电针组)。采用直结肠扩张(CRD)作为内脏的伤害性刺激。取脊髓腰膨大部位切片进行抗P2X4受体免疫染色,电镜观察脊髓腰膨大背角浅层内神经元和胶质细胞超微结构的变化。结果:行为学观察到电针组基础痛阈平均值较内脏痛组明显升高(63.3±6.45→31.2±2.77)mm Hg,两组比较,差异有统计学意义(P<0.01)。电镜观察到大鼠脊髓背角有P2X4受体阳性免疫反应产物分布在神经元和胶质细胞的细胞膜上;内脏痛组和电针组中神经元与胶质细胞内部存在突触样结构、缝隙连接等多种超微结构联系。结论:脊髓背角内P2X4受体免疫阳性神经元和胶质细胞存在超微结构改变可能是电针镇痛作用的形态学基础。

Objective： To observe the electron microscopic changes of P2X4 receptors expression and ultrastructure relationship of neurons and glia cells in lumbar spinal cord in visceral pain rats induced by noxious colon-rectum distention（CRD） with electro-acupuncture at zusanli point. Method： The 18 male SD rats were randomized divided into 3 groups： control group, visceral pain induced by CRD model group（VP） and electro-acupuncture（EA） Zusanli acupoint plus visceral pain group（EA Zusanli）. Colon-rectum Distention（CRD） was used as noxious visceral stimuli. By using immunoelectron microscopy, we investigated ultrastructural characters of junction areas between neurons and glial cells about immunohistochemical staining P2X4 receptors in the dorsal horn of lumbar enlargement segment spinal cord following VP stimulation. Results： Under the animal＇s behavioral reflection observation, the basic visceromotor response was greatly increased in EA group（63.3 ±6.45→31.2±2.77 mm Hg,P 0.01）,compared with VP group. The P2X4 receptors expression staining was mainly distributed in the cell membrane of neurons and glial cells in the superficial layer of dorsal horn of spinal cord. Immunoelectron microscopy studies established that some types of specialized ultrastructures were present in junction areas between neurons and glial cells within the superficial layer in spinal cord. Such as the synapse like structures, gap junctions. Conclusion： The ultrastructure changes of P2X4 receptors, neurons and glial cells in dorsal horn of lumbar spinal cord may be a kind of Morphological basis of acupuncture analgesic effects.