Bmal1敲除对糖尿病微血管内皮依耐性舒张功能的影响及机制

Effect and Mechanism of Bmal1 Knockout on Diabetic Microvascular Endothelium-Dependent Relaxation Function

摘要: 目的：探究生物钟基因Bmal1敲除对糖尿病微血管内皮依耐性舒张功能(EDR)的影响及机制。方法：对Bmal1全基因敲除(Bmal1−/−)的小鼠和野生型(WT)小鼠进行糖尿病造模，后从糖尿病造模成功的小鼠(DM)和造模对照组(Ctr)抽出Bmal1−/− + DM、Bmal1−/− + Ctr、WT + DM、WT + Ctr各5只，构成4个分组进行后续实验，血管张力仪测量4组小鼠肠系膜动脉血管段的EDR，Western blot检测血管内皮细胞中Bmal1及PPARδ通路蛋白的表达水平。结果：WT + DM组的EDR差于WT + Ctr组(P < 0.05)，但好于Bmal1−/− + DM组(P < 0.01)；Bmal1−/− + Ctr组和WT + Ctr组对比，Bmal1−/− + DM组和WT + DM组对比，Bmal1、PPARδ、DHFR的表达都是减少的(P < 0.01)，eNOS的解偶联是增加的(P < 0.01)。结论：糖尿病可引起微血管的EDR受损，Bmal1的敲除可加重糖尿病微血管的EDR损伤，PPARδ介导了Bmal1对EDR的影响。

Abstract: Objective: To explore the effect and mechanism of circadian clock gene Bmal1 knockout on diabetic microvascular endothelium-dependent relaxation (EDR). Methods: Inducing diabetes mellitus in Bmal1 knockout (Bmal1−/−) mice and wild-type (WT) mice, then choosing mice from diabetic mice (DM) and the control group (Ctr) to constitute 4 groups, Bmal1−/− + DM, Bmal1−/− + Ctr, WT + DM, WT + Ctr, each of 5 mice. The EDR of the mesenteric artery segments of the mice in the 4 groups was measured by vascular tensiometer, the expression levels of Bmal1 and PPARδ pathway proteins in vascular endothelial cells were tested by Western blot. Results: The EDR of the WT + DM group was worse than that of the WT + Ctr group (P < 0.05) but better than that of the Bmal1−/− + DM group (P < 0.01). Compared the Bmal1−/− + DM to the WT + DM group, compared the Bmal1−/− + Ctr to the WT + Ctr group, the expression levels of Bmal1, PPARδ, and DHFR were all decreased (P < 0.01), and the uncoupling of eNOS was increased (P < 0.01). Conclusion: Diabetes can cause damage to the EDR of microvascular, and the knockout of Bmal1 can aggravate the EDR damage of diabetic microvascular, PPARδ mediates the effects of Bmal1 on EDR.