NTs激活NCX1反向模式致膀胱过度活动症的机制研究

Overactive bladder (OAB) is of a high incidence and seriously affects the quality of life of patients. The underlying pathogenesis mechanism is complex, and the abnormal influx of calcium in detrusor cells is the key pathological process. In previou studies, we have found that NTs is responsiable for regulation of the bladder excitability by mediating the calcium ion influx, which can be blocked by the antagonist of transient receptor potential channel (TRP) M8 and sodium-calcium exchanger (NCX) 1. Both TRPM8 and NCX1 are involved in the regulation of bladder excitability and play an important role in the pathogenesis of OAB. TRPM8 is coupled with NCX1 structurally and functionally. The activition of TRPM8 can activate reverse mode of NCX1, which can result in the influx of calcium. Therefore, we hypothesized that NTs can activate TRPM8, and consequently promote the forward model exchanging into reverse model of NCX1, which can result in the occurrence of OAB. This stuy intends to verify the mechanism of NTs regulating NCX1 in clinical specimens, and interfere NTs/block TRPM8 to verify the mechanism of NTs regulating NCX1 through TRPM8 at the cellular level. Furthermore, we aim to verify this mechanism by administration with NTs and NCX1 blocker in animal models. This study will provide a new strategy for the diagnosis and treatment of OAB.

膀胱过度活动症（OAB）发病率高，严重影响患者生活质量。其发病机制复杂，逼尿肌细胞内钙离子异常增加是其核心环节。我们研究发现，神经降压素（NTs）可以调控胞内钙离子浓度参与膀胱兴奋性的改变，该调控作用可被瞬时受体电位通道（TRP）M8及钠钙交换体（NCX）1的阻滞剂所抑制。TRPM8和NCX1均参与了膀胱兴奋性的调控，在OAB的发病过程中发挥重要作用。两者在结构和功能上相偶联，TRPM8活化可激活NCX1的反向模式，介导钙离子内流。据此我们提出假说：NTs活化TRPM8，从而激活NCX1的反向模式参与OAB的发病。本研究拟在临床标本上验证NTs对NCX1的调控；在细胞水平，通过正反向干预NTs和阻断TRPM8及NCX1，验证NTs通过TRPM8对NCX1的调控机制；在构建TRPM8敲除小鼠的基础上建立OAB模型，通过加入NTs及阻断NCX1再次验证这一调控机制，以期为OAB诊治提供新思路。

膀胱过度活动症（OAB）是临床最常见的膀胱储尿期的兴奋性异常，其发病率高，严重影响患者的生活质量。随着人口老龄化的进一步发展，OAB的诊治需求日益增加,因此研究并阐明其发病机制具有重大的临床和社会价值。本项目围绕钙离子的重要调节蛋白钠钙交换体1（NCX1），通过构建梗阻后逼尿肌过度活动（DO）模型，研究该通道的表达变化以及参与膀胱过度活动症的潜在机制。结果显示，DO时大鼠膀胱内经典瞬时受体电势通道3(TRPC3)和NCX1的表达明显增加，两者在结构和功能上相偶联，TRPC3通过激活与其相偶联的NCX1的反向转运模式，介导逼尿肌细胞的钠离子的外排及钙离子的内流，进而引起胞内钙离子浓度的升高及膀胱兴奋性的增加。此外，我们还对间质性膀胱炎的发病机制进行了研究，在间质性膀胱炎大鼠中，尿紧张素Ⅱ及其受体UT的表达明显增加，U-II/UT高表达可通过激活RhoA/Rho激酶途径促进间质性膀胱炎相关膀胱过度活动的发生；最后，大鼠背跟神经节中大麻素受体GPR18激活后可通过抑制辣椒素受体TRPV1，从而改善间质性膀胱炎大鼠的痛觉过敏及膀胱过度活动症状。本项目研究成果共发表SCI论文5篇，其中IF>5分以上2篇。本课题基于临床上OAB的治疗效果欠佳，对其发病机制进行了探索性研究，以期为OAB及间质性膀胱炎的临床诊治提供理论依据和干预靶点。