艾塞那肽-4改善β淀粉样蛋白诱导的小鼠昼夜节律紊乱及时钟蛋白CLOCK蛋白的异常表达

Exendin-4 improves amyloid β-protein-induced mouse circadian rhythm disorders and CLOCK protein abnormal expression

目的探讨艾塞那肽(exendin)-4对β淀粉样蛋白(Aβ)引起的C57BL/6小鼠昼夜节律紊乱的影响,观察exendin-4对Aβ引起的海马时钟蛋白CLOCK蛋白异常表达的影响。方法海马内注射15 nmol Aβ31-35、50 pmol Exendin-4,对照组海马内注射等体积的高压三蒸水,利用Vital View跑轮分析软件观察各实验组小鼠昼夜节律的变化。蛋白质印迹法检测各组小鼠海马区CLOCK蛋白在不同时间的表达变化。结果 Aβ处理组小鼠出现明显昼夜节律紊乱,其自由运转周期为(23.67±0.05)h,鲁棒值为(22.5±4.3)%,与对照组比较差异有统计学意义(P<0.05),Exendin-4预处理组小鼠昼夜节律部分恢复正常,其自由运转周期为(23.53±0.05)h,鲁棒值为(47.0±4.0)%,与Aβ处理组比较差异有统计学意义(P<0.05)。蛋白质印迹法结果显示,对照组CLOCK蛋白在CT8和CT20表达高,在CT2和CT14时表达低,Aβ处理组CLOCK蛋白表达缺乏节律性,Exendin-4预处理组CLOCK蛋白部分恢复节律表达。结论 Exendin-4可部分恢复Aβ31-35导致的C57BL/6小鼠的昼夜节律紊乱,并部分纠正Aβ31-35引起的海马区CLOCK蛋白的异常表达。

Objective To investigate the effects of exendin-4 on amyloid amyloid β-protein（Aβ）-induced circadian rhythm disorders in C57BL/6 mice, and how Exendin-4 affects the Aβ-altered expression of hippocampal CLOCK protein in these mice. Methods The C57BL/6 mice received hippocampal injection of 15 nmol Aβ31-35 with or without 50 pmol Exendin-4. The C57BL/6 mice in the control group received hippocampal injection with same volume of distilled water. Vital View software was used to study the changes of circadian rhythm in each group of mice. West-ern blotting was used to detect the expression of hippocampal CLOCK protein at different time points in each group of mice. Results The mice treated with Aβ alone showed obviously circadian rhythm disorders, with a free-running period of（23.67±0.05）h and a robustness value of（22.5%±4.3）%, compared to those in the control group with statistically significant differences（P〈0.05）. The mice pretreated with Exendin-4 showed partially recovery to normal circadian rhythm, with a free-running period of（23.53±0.05）h and a robustness value of（47.0 ±4.0）%, compared to those in the Aβ treated group with statistically significant differences（P〈0.05）. Western blotting showed that the CLOCK protein expression in the control group was high at time points CT8 and CT20, and was low at time points CT14 and CT2;the CLOCK protein expression in the Aβ treated group did not show any rhythm, but showed partially recovered rhythm in the Exendin-4 pretreated group. Conclusion Exendin-4 may partially recover the circadian rhythm disorder induced by Aβ31-35 in C57BL/6 mice, and partially correct the abnormal CLOCK protein expression in mouse hippocampus altered by Aβ31-35.