左归降糖解郁方通过调控SIRT1/TORC1通路增加糖尿病并发抑郁症大鼠海马神经元树突棘密度

Effect of Zuogui-Jiangtang-Jieyu decoction on dendritic spines of hippo⁃campal neurons in diabetic rats with depression via SIRT1/TORC1 sig⁃naling pathway

目的:探明左归降糖解郁方调控糖尿病并发抑郁症大鼠海马SIRT1/TORC1信号通路并增加神经元树突棘的机制。方法:建立糖尿病并发抑郁症大鼠模型,并分别给予高、中、低剂量(20.52、10.26和5.13 g/kg)左归降糖解郁方。采用ELISA法测评各组大鼠血糖和胰岛素抵抗水平,采用强迫游泳实验和悬尾实验评价大鼠的抑郁样行为,采用Golgi-Cox染色观察海马神经元树突棘形态,采用Western blot法检测海马组织中SIRT1和TORC1蛋白表达。随后,给予模型大鼠海马脑区注射SIRT1的激动剂SRT2104和抑制剂sirtinol,研究SIRT1/TORC1信号通路影响树突棘形态的分子途径。最后,在给予高剂量左归降糖解郁方的基础上注射sirtinol,进一步明确左归降糖解郁方调控海马SIRT1/TORC1信号和树突棘密度的分子机制。结果:左归降糖解郁方可有效降低模型大鼠血糖含量和胰岛素抵抗指数,减少抑郁样行为,并显著改善大鼠海马神经元树突棘形态,增加海马SIRT1和TORC1蛋白表达。机制研究发现,SIRT1激动剂可显著增加海马TORC1、p-CREB和BDNF的表达及树突棘密度,而SIRT1抑制剂则显著抑制了左归降糖解郁方对模型大鼠海马TORC1、p-CREB和BDNF表达及树突棘密度的作用。结论:左归降糖解郁方可通过激活海马SIRT1/TORC1信号通路改善海马神经营养作用,从而进一步调节海马神经元树突棘形态。

AIM:To explore the mechanism of Zuogui-Jiangtang-Jieyu decoction increasing dendritic spines of hippocampal neuron in diabetic rats with depression via SIRT1/TORC1 signaling pathway.METHODS:The rats of diabetes complicated with depression were established and treated with high-,medium-and low-dose(20.52,10.26 and 5.13 g/kg)Zuogui-Jiangtang-Jieyu decoction.ELISA was used to measure the blood glucose and insulin resistance of the rats.The forced swimming test and the tail suspension test were used to evaluate the depression-like behavior.Golgi-Cox staining was used to observe the morphological changes of neuronal dendritic spines in the hippocampus.The SIRT1 and TORC1 protein expression was determined by Western blot.Subsequently,the activator or inhibitor of SIRT1 was injected into the hippocampus area of the diabetic rats complicated with depression,and the role of SIRT1/TORC1 signaling pathway in neuronal dendritic spines was assessed.Finally,on the basis of giving high-dose Zuogui-Jiangtang-Jieyu decoction,the inhibitor of SIRT1 was injected,and the role of SIRT1/TORC1 signaling pathway in the effect of Zuogui-Jiangtang-Jieyu decoction on dendritic spines was evaluated.RESULTS:Zuogui-Jiangtang-Jieyu decoction reduced the blood glucose level and insulin resistance index of diabetic rats with depression,and reversed the depression-like behavior.Furthermore,the density of dendritic spines and the expression of SIRT1 and TORC1 were increased by Zuogui-Jiangtang-Jieyu decoction.Additionally,SIRT1 activator significantly increased the protein levels of TORC1,p-CREB and BDNF in the hippocampus and enhanced the density of dendritic spines in diabetic rats with depression.The effects of Zuogui-Jiangtang-Jieyu decoction on the protein levels of TORC1,p-CREB and BDNF and the density of dendritic spine were inhibited by SIRT1 inhibitor.CONCLUSION:Zuogui-Jiangtang-Jieyu decoction regulates the dendritic spines of hippocampal neurons in diabetic rats with depression by increasing the p-CREB and BDNF protein levels through activating SIRT1/TORC1 signaling pathway.