神经病理性疼痛大鼠脊髓背角小胶质细胞及星形胶质细胞数量的体视学研究

Stereological study of the numbers of microglia and astrocytes in the spinal dorsal horn of neuropathic pain rats

目的探讨坐骨神经慢性限制性损伤(CCI)所致神经病理性痛大鼠脊髓背角内小胶质细胞和星形胶质细胞的数量改变以及帕瑞昔布干预的作用。方法 12只正常成年二级SD大鼠随机分为2组:CCI组(n=7)行单侧坐骨神经松结扎,对侧不做任何处理;帕瑞昔布组(n=5)手术同CCI组,术后3 d连续腹腔注射帕瑞昔布3 mg/kg。术前1 d、术后第4、7、14及28 d测定大鼠50%缩腿阈值(PWT)。术后第28 d测定PWT后取L5脊髓制作石蜡包埋连续切片,按等距随机原则抽选5张切片行GFAP(标记星形胶质细胞)免疫组化染色,采用体视学方法估计脊髓背角内毛细血管腔的面积、星形胶质细胞、少突胶质细胞和内皮细胞的数量。结果 CCI术后4～28 d,CCI组与帕瑞昔布组大鼠手术侧的PWT显著低于对侧未手术侧;帕瑞昔布组手术侧的PWT显著高于CCI组手术侧(P<0.05)。术后28 d,与未手术侧相比,CCI组和帕瑞昔布组大鼠手术侧脊髓背角内毛细血管的面积无显著改变,单位长度脊髓背角内星形胶质细胞、少突胶质细胞和毛细血管内皮细胞的数量差异无显著性。结论神经病理性痛亚急性期,大鼠脊髓背角无明显的炎症反应,背角内小胶质细胞和星形胶质细胞的数量无改变。

Objective To determine whether neuropathic pain （NNP） induced by chronic constriction injury （CCI） is associated with changes in the number of microglia and astrocytes in the spinal dorsal horn of rats and the effects of COX-2 inhibitor on NNP. Methods Twelve class II adult SD rats were randomly divided into two groups： the CCI group （7 rats） was subjected to unilateral loose ligation of the sciatic nerve; and the parecoxib group （5 rats） was treated as CCI group and then intraperitoneally injected with parecoxib 3 mg/kg twice a day on postoperative days 1 -3. The paw withdraw threshold （PWT） was measured on preoperative day 1, and postoperative days 4, 7, lg and 28. The rats were sacrificed 28 days after operation, and the L5 segment of spinal cord was removed and paraffin-embedded serial sections were prepared and stained with GFAP immunohistochemical staining to show astrocytes. The areas of cap- illary lumens and the number of microglia, astrocytes and endothelial cells in the spinal dorsal horn were estimated using stereological techniques. Results At 4 to 28 days after CCI, the PWT on the operated side was significantly decreased in both groups, compared with that on the non-operated side. PWT in the parecoxib group was significantly higher than that in the CCI group. In the CCI group and parecoxib group, 28 days post operation, the area of capillary lumens and the number of microglia, astrocytes and endothelial cells in the spinal dorsal horn were not significantly different, compared with those on the non- operated side, and no inflammatory cell infiltration was found. Conclusions In the subacute phase of neuropathic pain, there are no significant inflammatory response and changes in the numbers of microglia and astrocytes in the rat spinal dorsal horn.