不同强度运动抑制糖尿病大鼠肾脏PI3K/AKT/mTOR信号通路改善自噬的比较

Comparison of different intensity exercises to improve autophagy in diabetic rats by inhibiting renal phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway

背景:2型糖尿病损害肾功能。研究表明运动干预可以保护肾脏;鸢尾素可以通过抑制磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路恢复自噬,保护糖尿病肾病患者的肾功能。目的:探讨运动能否通过抑制肾脏磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路过度激活来恢复自噬,改善肾损伤,以及分析不同方式运动产生影响的差异。方法:将6周龄的SD大鼠随机分为空白对照组(正常大鼠)和糖尿病组,其中糖尿病组大鼠经过高脂高糖喂养加腹腔注射低剂量1%链脲佐菌素(30 mg/kg)建立2型糖尿病模型。造模成功后再将糖尿病组大鼠随机分成糖尿病模型组、中强度持续运动组和高强度间歇运动组。两个运动组大鼠分别进行8周不同强度运动干预。取材后采用葡萄糖氧化酶法检测大鼠空腹血糖,使用试剂盒检测糖化血红蛋白水平,Elisa法检测血清胰岛素浓度,计算胰岛素抵抗指数,RT-PCR检测肾组织磷脂酰肌醇3-激酶、蛋白激酶B、雷帕霉素靶蛋白、Beclin-1、podocin、nephrin的基因表达量,Western Blot检测肾组织雷帕霉素靶蛋白及自噬标记蛋白LC3-1、LC3-2、Beclin-1的蛋白表达量。结果与结论:①2型糖尿病大鼠空腹血糖和糖化血红蛋白水平极显著性升高,胰岛素抵抗水平显著上升,胰岛素水平显著下降;两种运动均能使2型糖尿病大鼠空腹血糖和糖化血红蛋白水平极显著下降,胰岛素抵抗水平显著下降,胰岛素水平显著上升;与中强度持续运动组相比,高强度间歇运动组胰岛素水平显著上升。②2型糖尿病大鼠podocin、nephrin基因表达量显著降低;两种不同形式运动均能显著提高其表达;与高强度间歇运动组相比,中等强度持续性运动组足细胞相关蛋白基因表达有进一步上升趋势,但无显著性差异。③2型糖尿病大鼠肾组织磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及蛋白的表达量显著增加,自噬标志蛋白Beclin-1、LC3-2表达量以及LC3-2/LC3-1显著降低;两种不同形式运动均能使肾组织磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及雷帕霉素靶蛋白蛋白的表达量显著降低,自噬标志蛋白Beclin-1、LC3-2以及LC3-2/LC3-1显著升高;与中等强度持续性运动组相比,高强度间歇运动的磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及雷帕霉素靶蛋白的蛋白表达量有进一步下降的趋势,Beclin-1、LC3-2以及LC3-2/LC3-1有进一步升高的趋势,但仅Beclin-1有显著性差异。④结果说明2型糖尿病肾脏足细胞损伤,自噬受到抑制,与磷脂酰肌醇3-激酶/蛋白激酶B/mTORC1信号通路被异常激活密切相关。高强度间歇运动和中等强度持续性运动可以保护糖尿病肾脏,减少足细胞损伤,促进自噬恢复,这可能与运动抑制磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路过度激活有关。与中等强度持续性运动相比,高强度间歇运动恢复自噬的效果呈更优趋势,但足细胞蛋白表达稍有下降。

BACKGROUND:Type 2 diabetes mellitus impairs renal function,and studies have shown that exercise interventions can protect the kidneys.Irisin can protect renal function in diabetic nephropathy patients by restoring autophagy through inhibition of the phosphoinositide 3-kinase(PI3K)/protein kinase B(Akt)/mammalian target of rapamycin(mTOR)signaling pathway.OBJECTIVE:To explore whether exercise can restore autophagy and ameliorate renal injury by inhibiting over-activation of the renal PI3K/Akt/mTOR signaling pathway,as well as to analyze the differences in the effects of different modalities of exercise.METHODS:Six-week-old Sprague-Dawley rats were randomly divided into a blank control group(normal rats)and a diabetic group,and then the diabetic group was randomly divided into a diabetic model group,a moderate-intensity continuous exercise group,and a high-intensity intermittent exercise group after successful modeling using high-fat,high-sugar feeding plus intraperitoneal administration of low-dose 1%streptozotocin(30 mg/kg).The two exercise groups were subjected to 8 weeks of exercise intervention with different exercise intensities.The fasting blood glucose concentration was detected by glucose oxidase method,glycated hemoglobin levels was measured using a kit,serum insulin concentration was detected by Elisa method,and insulin resistance index was calculated.Gene expression of PI3K,AKT,mTOR,Beclin-1,podocin,and nephrin was detected by RT-PCR.Protein expression of mTOR and autophagy marker proteins LC3-1,LC3-2,and Beclin-1 was detected by western blot RESULTS AND CONCLUSION:Fasting blood glucose and glycosylated hemoglobin levels were highly significantly increased,insulin resistance levels were significantly increased,and insulin levels were significantly decreased in type 2 diabetic rats.Both exercises resulted in highly significant decreases in fasting blood glucose and glycosylated hemoglobin levels,significant decreases in insulin resistance levels and significant increases in insulin levels in type 2 diabetic rats.Insulin levels were significantly higher in the high-intensity intermittent exercise group compared with the moderate-intensity continuous exercise group.The expression of podocin and nephrind genes was significantly reduced in type 2 diabetic rats and two different forms of exercise significantly the gene expression.There was a further trend toward an increase in gene expression of podocyte-associated proteins in the moderate-intensity continuous exercise group compared with the high-intensity intermittent exercise group,but there was no significant difference.The mRNA and protein expression of PI3K,AKT and mTORC1 in kidney tissues of type 2 diabetic rats were significantly increased,and the expression of autophagy marker proteins Beclin-1 and LC3-2 and LC3-2/LC3-1 were significantly decreased.Both different forms of exercise significantly decreased the mRNA and protein expression of PI3K,AKT,and mTORC1,and significantly increased the autophagy marker proteins Beclin-1,LC3-2,and LC3-2/LC3-1 in renal tissues.Compared with the moderate-intensity continuous exercise group,there was a trend toward further decreases in mRNA expression of PI3K,AKT,and mTORC1 and protein expression of mTOR,and a trend toward further elevation of Beclin-1,LC3-2,and LC3-2/LC3-1 in the high-intensity intermittent exercise group,but only Beclin-1 showed a significant difference between groups.In summary,renal podocyte injury in type 2 diabetes mellitus with suppressed autophagy is closely related to aberrant activation of the PI3K/AKT/mTORC1 signaling pathway.Both moderate-intensity continuous exercise and high-intensity intermittent exercise can protect the diabetic kidney,reduce podocyte damage,and restore renal podocyte autophagy,which may be achieved by inhibiting the excessive activation of the PI3K/AKT/mTOR signaling pathway.High-intensity intermittent exercise shows a trend toward more favorable restoration of autophagy compared with moderate-intensity continuous exercise,but with a slight decrease in podocyte protein expression.