BDNF/TrkB通路活化星形胶质细胞对大鼠神经病理性痛的影响

Contribution of BDNF/TrkB pathway to development of neuropathic pain by activation of astrocytes in rats

目的观察外源性脑源性神经营养因子(BDNF)对大鼠机械痛阈和星形胶质细胞的影响,探讨BDNF参与疼痛调控的可能机制。方法将30只鞘内置管成功的大鼠随机分为空白对照组、安慰剂组、BDNF组、BDNF+星形胶质细胞抑制剂组(BDNF+氟代柠檬酸组)及BDNF+酪氨酸激酶受体B(TrkB)抑制剂组(BDNF+K252a组),每组6只。予鞘内注入药物,1次/d×7 d。每次注药前1 h测定50%机械缩爪阈值(50%PWT);末次给药后1 h取脊髓腰膨大,Western blotting法测定胶质细胞纤丝酸性蛋白(GFAP)及磷酸化TrkB的蛋白表达。结果 BDNF组大鼠后肢50%PWT较空白对照组显著下降(P<0.05);给药后第7天,BDNF组大鼠脊髓腰膨大GFAP和磷酸化TrkB的蛋白表达较空白对照组显著升高(P<0.01)。BDNF+氟代柠檬酸组和BDNF+K252a组50%PWT和GFAP蛋白表达水平与空白对照组比较,差异无统计学意义(P>0.05)。BDNF+K252a组磷酸化TrkB的蛋白表达与空白对照组比较,差异无统计学意义(P>0.05)。结论 BDNF可能通过磷酸化TrkB受体使脊髓星形胶质细胞活化,进而参与神经病理性痛的发生和发展过程。

Objective To investigate the effects of exogenous brain-derived neurotrophic factor（BDNF） on mechanical pain threshold and astrocytes,and explore the potential mechanism of BDNF-induced pain.Methods Thirty rats with successful intrathecal catheterization were randomly divided into blank control group,placebo group,BDNF group,BDNF＋astrocyte inhibitor group（BDNF＋fluorocitrate group） and BDNF＋tyrosine kinase receptor B（TrkB） inhibitor group（BDNF＋K252a group）,with 6 rats in each group.Intrathecal administration was performed once daily for 7 d.Fifty percent paw withdrawal threshold（50% PWT） was measured 1 h before each injection.Spinal enlargement parts were obtained 1 h after the last administration,and the expression of glial fibrillary acidic protein（GFAP） and phosphorylated TrkB protein was detected by Western blotting.Results Compared with blank control group,50% PWT of hind limbs in BDNF group was significantly lower（P0.05）.Seven days after administration,the expression of GFAP and phosphorylated TrkB protein in spinal enlargement parts in BDNF group was significantly higher than that in blank control group（P0.01）.The expression of GFAP protein and 50% PWT in BDNF＋ fluorocitrate group and BDNF＋K252a group were not significantly different from those in blank control group（P0.05）.There was no significant difference in the expression of phosphorylated TrkB protein between BDNF＋K252a group and blank control group（P0.05）.Conclusion BDNF may activate astrocytes via phosphorylated TrkB receptor,which in turn produce neuropathic pain.