高表达瞬时电位受体通道1在大鼠弥漫性轴索损伤中的作用机制

The mechanism of high expression of TRPC1 in diffuse axnoal injury of rats

目的研究瞬时电位受体通道1(TRPC1)在弥漫性轴索损伤(DAI)中的作用,探讨TRPC1在DAI后神经元钙超载及髓鞘变性中的机制。方法瞬间旋转损伤法建立大鼠DAI模型,用SKF96365干扰TRPC1通道活性后建立DAI干预组,Fura-2AM检测胞内Ca2+浓度,Western blot和免疫组化检测皮层TRPC1蛋白的动态表达,并与正常组、DMSO对照组相比较,电镜检测神经元及髓鞘改变,TUNEL检测皮层神经元凋亡。单因素方差分析数据。结果 DAI后皮层中TRPC1蛋白表达升高,在1d达到高峰,随后逐渐下降,同时皮层神经元胞内Ca2+浓度在1d达到峰值,髓鞘结构破坏。给予TRPC1通道阻断剂SKF96365后,皮层TRPC1蛋白表达被抑制,皮层神经元钙内流减低,髓鞘结构部分保留,神经功能评分改善。结论 DAI后TRPC1导致的钙超载是造成髓鞘变性及神经元死亡的重要原因,抑制TRPC1产生的钙内流可保护髓鞘结构完整,减轻神经元凋亡。

Objective To investigate the possible role of canonical transient receptor potential channel 1 （TRPC1） after diffuse axonal injury （DAD and discuss the mechanism of TRPC1 involved in calcium overload of neurons and myelin degeneration after DAI. Methods Rat models of DAI were established with the method of rotational acceleration of the brain. DAI intervention group was established by using SKF96365 intracerebroventricular injection. Intracellular calcium concentration was detected by Fura-2AM. The dynamic expressions of TRPC1 in the cortex were determined by Western blot and immunohistochemical staining. The results were compared with those in DMSO control group and normal group. The changes of neurons and myelin sheath were detected under electron microscope. The apoptosis of cortical neurons was detected by TUNEL. One-way ANOVA was used to compare within each group. Results The protein expressions of TRPC1 in the cortex increased after DAI and reached the peak at day 1 and then gradually decreased while intracellular calcium concentration also reached the peak at day 1. The structure of myelin sheath was destructed at the same time. After injection of TRPC1 blocker SKF96365, the protein expression of TRPC1 was inhibited and intracellular calcium concentration decreased. Meanwhile, the structure of myelin sheath was partially reserved and the scores of neurologicalfunctions in rats were improved. Oonclusion TRPCl-induced calcium overload after DAI is the major cause of myelin degeneration and neuronal death. Suppressing the calcium influx induced by TRPC1 can protect the normal structure of myelin and improve neuronal apoptosis.