平滑肌细胞BKCa通道"昼夜节律"的改变在STZ诱导的2型糖尿病大鼠脑动脉损伤重建中的作用

Cerebrovascular complications is one of deadly causes of diabetic patientes. However, the mechanisms of pathogenesis and progression in diabetic vascular complications remain unknown and there are still no effective treatments. The large conductance calcium-activated K+ (BKCa) channels are highly expressed in vascular smooth muscle cells (VSMCs) and play an essential role in the regulation of vascular function and structure. Our previous work has demonstrated that activities of BKCa channel decreased in STZ-induced diabetic mice and high glucose suppressed apoptosis of VSMCs by inhibiting BKCa channel.Furthermore, we also demonstrated that the function of BKCa channel decreased not only in daytime (12 h light) but also in nighttime (12 h dark) in STZ-induced type 2 diabetic rats. These results suggested that the circadian regulation of BKCa channels changed in cerebral arterial remodeling of diabetic rats. However, the precise mechanisms remain to be determined. In the present study, we want to investigate the role of circadian regulation of BKCa channels in STZ-induced type 2 diabetic rats with electrophysiology, molecular biology, culture cell, and cell transformation techniques in vivo and in vitro. Our study may provide a novel mechanism for cerebrovascular remodeling in diabetic rats. We also want to find the zeitgeber medicine for the diabetic vascular complications.

糖尿病性脑血管病变是糖尿病患者死亡或致残的主要原因，其发生机理目前仍不甚清楚，也缺乏有效的防治措施。大电导钙激活钾通道（BKCa）在血管平滑肌细胞（VSMCs）上分布广泛，对血管功能与结构起着重要的调控作用。我们前期工作已证实STZ诱导的糖尿病小鼠脑动脉VSMCs BKCa通道活性降低，且高糖可通过降低BKCa通道活性抑制VSMCs凋亡。我们最新还发现STZ诱导的糖尿病大鼠脑动脉BKCa通道在白天（12 h光照）与夜间（12 h黑暗）的功能均显著降低且波动性变小，提示BKCa通道"昼夜节律"的改变可能参与糖尿病大鼠脑动脉损伤过程。本项目拟采用电生理膜片钳、分子生物学方法、血管体外培养与细胞转染等技术从动物整体、器官、细胞与基因等多个水平探讨BKCa通道"昼夜节律"的改变机理及其在糖尿病大鼠脑动脉损伤中的作用。本项目可对糖尿病血管损伤机理提出新的思路，并希望找到受时因子药物作为新的防治措施。

糖尿病性脑血管病变是糖尿病患者死亡或致残的主要原因，其发生机理目前仍不甚清楚，也缺乏有效的防治措施。大电导钙激活钾通道（large-conductance calcium-activated K+ channel, BKCa）在血管平滑肌细胞（vascular smooth muscle cells, VSMCs）膜上表达丰富，对血管功能与结构起着重要的调控作用。本研究证实糖尿病大鼠脑动脉VSMCs BKCa通道的昼夜节律发生改变，进而调控脑动脉血管的功能与凋亡率的变化，其机制涉及上游的Per-2、Bmal1与dbp等时钟基因和circRNA与LncRNA信号分子、下游涉及VSMCs胞内Ca2+浓度、BKCa通道亚基的表达变化，具体表现为1）STZ诱导的2型糖尿病大鼠日间与夜间收缩压与舒张压均显著增加，但昼夜振荡幅度显著缩小。2) 糖尿病大鼠脑动脉BKCa通道的功能与表达发生似昼夜节律的紊乱，其机制涉及上游外周节律基因（per-2、bmal1与dbp）、circRNA与LncRNA等信号分子表达的改变，其下游涉及VSMCs胞内Ca2+浓度的变化与BKCa通道亚基的变化。3)给予糖尿病大鼠小檗碱或者红景天苷等中药进行治疗，其可通体调节BKCa通道活性参与糖尿病血管的保护作用。总之，本项目通过电生理膜片钳、分子生物学方法、血管体外培养与细胞转染等技术从动物整体、器官、细胞与基因等多个水平发现糖尿病大鼠脑动脉BKCa通道昼夜节律的改变机制，本研究对揭示糖尿病性脑动脉血管的损伤机制和防治策略提出了新的思路。