福尔马林炎性痛对星形胶质细胞活化的影响

Effects of formalin-induced inflammatory pain on astrocyte activation

摘要目的：研究福尔马林炎性痛对中枢神经系统星形胶质细胞活化的影响。方法：成年健康SD大鼠，随机分为正常组、实验组和生理盐水组；实验组左后足底注射4％福尔马林100肛l建立炎性痛模型，并分为注射后30min、60min、3h、6h、12h、1d、3d、7d、15d等9个时间点。组织常规石蜡包埋，应用免疫组织化学显色和ImageJ图像分析检测星形胶质细胞标志物GFAP在脊髓、脑和海马内的表达和分布。结果：正常组和生理盐水组脊髓、脑和海马内GFAP有少量表达；实验组脊髓、脑和海马内的GFAP阳性细胞数和光密度值在60min～3h开始增加，1～3d达到峰值，随后开始下降，15d降至正常水平，阳性细胞呈现增殖和肥大两种形态学改变。结论：福尔马林炎性痛大鼠脊髓、脑和海马内星形胶质细胞被激活，可能参与炎性痛形成、维持与恶化。

Objective： To investigate effects of formalin-induced inflammatory pain on astrocyte activation. Methods： In this experiment, heathy adult SD rats were randomly divided into normal group, experimental group and saline group. Experi- mental groups were subdivided into 9 post-injection groups： 30 rain, 60 min, 3 h, 6 h, 12 h, 1 d, 3 d, 7 d, 15 d. To set up inflammatory pain model, 5% formalin （100 μl was subcutaneously injected into the plantar of the left hindpaw in rats. The tissues were conventionally embedded in paraffin. To detect expression and distribution of iconic protein GFAP of astrocytes in the spinal cord, brain and hippocampus, immunohistochemistry and image analysis were used. Results： A small number of GFAP positive cells was detected in the spinal cord, brain and hippocampus in normal group and saline group. GFAP positive ceils and its optic density （OD） in experimental groups began to significantly increase at 60 min-3 h, reached peak at 1-3 d after formalin injection compared to the normal and saline groups. Its expression subseqently began to decline, to normal level at 15 d. The GFAP positive cells present two kinds of pathological changes of proliferation and hypertrophy. Conclusion： In the formalin-induced inflammatory pain, astrocytes in the spinal cord, brain and hippocampus are activated and may participate in formation and maintance of the inflammatory pain.