TRPV4-AQP1对大鼠背根神经节持续压迫痛觉过敏的调控及机制研究

Chronic compression of dorsal root ganglion (DRG) (CCD) is a typical model of neuropathic pain. It presents spontaneous pain, mechanical allodynia, and thermal hyperalgesia. Transient receptor potential vanilloid (TRPV4) is reported to contribute to the allodynia in CCD rats by increasing the concentration of cyclic guanosine monophosphate (cGMP) and the internal flow of Ca2+. For AQP1 is a cGMP-gated channel and the existence of a Ca2+-binding site at the C-terminus of AQP1, it could be regulated by the activation of cGMP and the increase of [Ca2+]i. In CCI, the expression and activity of AQP1 decrease. AQP1 colocalizes with TRPV1, and is regulated by the inhibitors of TRPV1. Therefore, TRPV4 may accommodate the function and expression of AQP1 by increasing the concentration of cGMP or Ca2+, to regulate the allodynia of CCD rats. Thus, in this study, siRNA, behavioral testing, western blot, and real-time PCR technique will be used to verify the role of TRPV4-AQP1 in CCD-induced allodynia, to further provide new point of view for the neuropathic pain.

背根神经节（DRG）持续受压(CCD)后，DRG中瞬时感受器电位离子通道（TRPV4）的功能和表达增强，细胞内Ca2+浓度增加，大鼠出现痛觉过敏和异常疼痛。TRPV4也可通过环磷酸鸟苷（cGMP）调控CCD大鼠的痛觉过敏。水通道蛋白1（AQP1）为cGMP门控性通道，C末端含有Ca2+结合区，其活性和表达可被细胞内Ca2+浓度的升高调控，参与坐骨神经损伤和缓激肽注射后的痛觉过敏传导。AQP1与TRPV1（TRPV4同源性通道）共定位，其功能可被TRPV1抑制剂调节。因此，我们提出假说：TRPV4可能通过cGMP和Ca2+两条途径调控AQP1通道，进而调控CCD大鼠痛觉过敏。本课题拟建立CCD大鼠模型，采用siRNA干扰、行为学检测、分子生物学及激光共聚焦等技术，明确TRPV4-AQP1途径在CCD模型所致痛觉过敏中的作用，探明TRPV4对AQP1的调控机制，为病理性疼痛的治疗提供新的思路。

大鼠背根神经节（dorsal root ganglion，DRG）持续受压（chronic compression of DRG，CCD）模型是一种典型的神经病理性疼痛模型，CCD大鼠可出现自发性的疼痛、机械痛敏、热痛敏和异常疼痛，并且伴随着神经元自发性放电的增加、动作电位的降低和电流阈值的降低。瞬时感受器电位离子通道家族中香草素受体亚家族4（transient receptor potential vanilloid receptor 4，TRPV4）可调控CCD大鼠的机械痛敏，而AQP1的慢病毒和抑制剂可降低TRPV4的蛋白表达，进而缓解CCD大鼠的机械痛敏；鞘注AQP1慢病毒后CCD大鼠DRG中cGMP的浓度降低，鞘注cGMP抑制剂后TRPV4蛋白表达下调，CCD大鼠的痛敏降低，因此，AQP1可通过cGMP调控 TRPV4的表达进而调控CCD大鼠的机械痛敏。此外，大鼠背根神经节持续受压后脊髓背角AQP1、TRPV4的蛋白表达增加，cGMP的浓度增加，鞘内注射AQP1慢病毒后cGMP浓度和TRPV4蛋白表达降低，鞘注cGMP抑制剂后TRPV4蛋白表达降低，AQP1可通过cGMP调控TRPV4的表达进而调控CCD大鼠神经病理性疼痛的中枢敏化。同时，CCD大鼠DRG及脊髓背角AQP4表达上调，AQP4可能参与CCD大鼠痛敏的调控，为神经病理性疼痛的治疗提供新的思路。