丘脑脑源性神经生长因子-酪氨酸激酶受体B信号介导脑缺血诱发的痛觉过敏

The thalamic BDNF⁃TrkB signaling pathway mediates cerebral ischemia⁃induced hyperalgesia

目的基于丘脑BDNF信号探讨实验性脑缺血大鼠模型脑卒中痛觉过敏的病理机制。方法选用8周龄雄性Wistar大鼠,运用大脑中动脉阻塞方法复制大鼠脑缺血再灌注模型,利用热板法测定大鼠热痛阈,设置假手术组(SHAM),筛选术后3 d出现痛觉过敏的大鼠为脑卒中后中枢性疼痛组(central post⁃stroke pain,CPSP),运用TTC染色,HE染色、尼氏染色和Neun免疫组化染色确认大鼠丘脑损伤,运用免疫荧光检测丘脑小胶质细胞活化与BDNF表达情况,运用Western blot检测丘脑BDNF、TrkB、GABAAR蛋白的表达。结果与假手术组相比,模型组神经功能评分升高,热痛阈显著降低,TTC染色丘脑出现梗死区域,丘脑VPL区出现病理损伤,尼氏体数量减少,Neun阳性表达降低,小胶质细胞数量和BDNF表达增加,且小胶质细胞与BDNF存在共表达,丘脑BDNF、Trkb蛋白表达量升高,GABAAR蛋白表达量降低。结论脑缺血损伤可诱发痛觉过敏症状的发生,发病率可达30%左右,丘脑小胶质细胞激活伴随的BDNF⁃Trkb信号在介导脑卒中后痛觉过敏的病理进展方面有重要作用。

Objective Explore the pathological mechanism of stroke hyperalgesia by using a rat model of thalamic BDNF signaling.Methods Wistar male rats(8 weeks old)were used in the study.The model of focal cerebral ischemia and reperfusion in rats were established by middle cerebral artery occlusion(MCAO).The change of thermal pain threshold were assessed by hot plate tests.The rats were divided into two groups randomly:SHAM and central post⁃stroke pain(CPSP).Rats with hyperalgesia 3 days after surgery were screened for the post⁃stroke central pain group.TTC staining,HE staining,Nissl staining and Neun immunohistochemical staining were used to assess thalamus damage.Immunofluorescence was used to detect the number of activated microglia and BDNF.The expression of BDNF,TrkB and GABAAR proteins was determined by Western blot.Results When compared to the SHAM group,the CPSP rats had a significantly higher neurological deficit score,a lower heat pain threshold,thalamic VPL pathology injury,a lower number of nissl body and Neun positive expression,higher microglia and BDNF expression,higher thalamic BDNF and Trkb protein expression,and lower GABAAR protein expression.Conclusions Ischemia/reperfusion cerebral injury can result in hyperalgesia,with a 30%dis⁃ease incidence.The concomitant BDNF⁃Trkb of thalamic microglia activation plays a major role in mediating the pathological progression of hyperalgesia after stroke.