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Abstract：
OBJECTIVE: To explore the mechanisms mediating the protective effect of carnosine against nephropathy in rats with diabetes mellitus (DM).
METHODS: Rat models of DM established by high-fat diet feeding and streptozotocin injection were randomized into DM group and 3 treatment groups with daily carnosine treatment at 100, 300, and 900 mg/kg. Body weight and blood glucose level changes of the rats were measured regularly. After the treatment, 24-h urine, serum samples and kidneys of the rats were collected to measure urine volume, urine protein content, blood creatinine, and kidney mass; renal pathology was observed using HE staining, and MDA content and SOD activity in the kidney tissues were detected. Western blotting was performed to detect the protein expressions of p-AKT, AKT, p-mTOR, mTOR, LC3 and p62 in the kidney tissues.
RESULTS: Compared with normal control rats, the diabetic rats exhibited dull and wet hair and showed decreased body weight, increased blood glucose, urinary protein content, 24-h urine volume, blood creatinine, and kidney mass with obvious swelling and deformation of the glomeruli, narrowing of the renal tubules, decreased SOD activity and increased MDA content, lowered p-mTOR/mTOR and p-AKT/AKT ratios and increased LC3 Ⅱ/Ⅰ ratio and p62 protein expression in the kidney tissue. The diabetic rats receiving carnosine treatments had dry hair with normal luster and showed increased body weight and slightly decreased blood glucose, urinary protein content, 24-h urine volume, blood creatinine, and kidney mass. The treatment also improved renal pathology, increased SOD activity, decreased MDA content, increased p-mTOR/mTOR and p-AKT/AKT ratios and lowered LC3 Ⅱ/Ⅰ ratio and p62 protein expression in renal tissue of the diabetic rats.
CONCLUSIONS: Carnosine offers protection against nephropathy in rats with DM possibly by inhibiting oxidative stress, activating the AKT/mTOR pathway, and restoring autophagy in the kidneys.
METHODS: Rat models of DM established by high-fat diet feeding and streptozotocin injection were randomized into DM group and 3 treatment groups with daily carnosine treatment at 100, 300, and 900 mg/kg. Body weight and blood glucose level changes of the rats were measured regularly. After the treatment, 24-h urine, serum samples and kidneys of the rats were collected to measure urine volume, urine protein content, blood creatinine, and kidney mass; renal pathology was observed using HE staining, and MDA content and SOD activity in the kidney tissues were detected. Western blotting was performed to detect the protein expressions of p-AKT, AKT, p-mTOR, mTOR, LC3 and p62 in the kidney tissues.
RESULTS: Compared with normal control rats, the diabetic rats exhibited dull and wet hair and showed decreased body weight, increased blood glucose, urinary protein content, 24-h urine volume, blood creatinine, and kidney mass with obvious swelling and deformation of the glomeruli, narrowing of the renal tubules, decreased SOD activity and increased MDA content, lowered p-mTOR/mTOR and p-AKT/AKT ratios and increased LC3 Ⅱ/Ⅰ ratio and p62 protein expression in the kidney tissue. The diabetic rats receiving carnosine treatments had dry hair with normal luster and showed increased body weight and slightly decreased blood glucose, urinary protein content, 24-h urine volume, blood creatinine, and kidney mass. The treatment also improved renal pathology, increased SOD activity, decreased MDA content, increased p-mTOR/mTOR and p-AKT/AKT ratios and lowered LC3 Ⅱ/Ⅰ ratio and p62 protein expression in renal tissue of the diabetic rats.
CONCLUSIONS: Carnosine offers protection against nephropathy in rats with DM possibly by inhibiting oxidative stress, activating the AKT/mTOR pathway, and restoring autophagy in the kidneys.
摘要：
目的：探讨肌肽对糖尿病大鼠肾病保护作用的机制。
方法：采用高脂饮食喂养和链脲佐菌素注射建立DM大鼠模型，随机分为DM组和3个治疗组，每天肌肽治疗100、300和900mg/kg。定期测量大鼠的体重和血糖水平变化。治疗后,24小时尿液，收集大鼠的血清样本和肾脏以测量尿量，尿蛋白含量,血肌酐,肾脏肿块；HE染色观察肾脏病理，检测肾组织中MDA含量和SOD活性。蛋白质印迹法检测p-AKT蛋白的表达,AKT,p-mTOR,mTOR,肾组织中的LC3和p62。
结果：与正常对照组大鼠相比，糖尿病大鼠表现出暗淡和潮湿的头发，并显示出体重下降，血糖升高,尿蛋白含量，24小时尿量，血肌酐,和肾脏肿块，肾小球明显肿胀和变形，肾小管变窄，降低SOD活性和增加MDA含量,肾组织中p-mTOR/mTOR和p-AKT/AKT比值降低，LC3Ⅱ/Ⅰ比值和p62蛋白表达增加。肌肽治疗的糖尿病大鼠头发干燥，光泽正常，体重增加，血糖略有下降，尿蛋白含量，24小时尿量，血肌酐,和肾脏质量。治疗还改善了肾脏病理，增加SOD活性，MDA含量降低，糖尿病大鼠肾组织中p-mTOR/mTOR和p-AKT/AKT比值升高,LC3Ⅱ/Ⅰ比值和p62蛋白表达降低。
结论：肌肽可能通过抑制氧化应激对DM大鼠肾病具有保护作用，激活AKT/mTOR通路，恢复肾脏的自噬。
方法：采用高脂饮食喂养和链脲佐菌素注射建立DM大鼠模型，随机分为DM组和3个治疗组，每天肌肽治疗100、300和900mg/kg。定期测量大鼠的体重和血糖水平变化。治疗后,24小时尿液，收集大鼠的血清样本和肾脏以测量尿量，尿蛋白含量,血肌酐,肾脏肿块；HE染色观察肾脏病理，检测肾组织中MDA含量和SOD活性。蛋白质印迹法检测p-AKT蛋白的表达,AKT,p-mTOR,mTOR,肾组织中的LC3和p62。
结果：与正常对照组大鼠相比，糖尿病大鼠表现出暗淡和潮湿的头发，并显示出体重下降，血糖升高,尿蛋白含量，24小时尿量，血肌酐,和肾脏肿块，肾小球明显肿胀和变形，肾小管变窄，降低SOD活性和增加MDA含量,肾组织中p-mTOR/mTOR和p-AKT/AKT比值降低，LC3Ⅱ/Ⅰ比值和p62蛋白表达增加。肌肽治疗的糖尿病大鼠头发干燥，光泽正常，体重增加，血糖略有下降，尿蛋白含量，24小时尿量，血肌酐,和肾脏质量。治疗还改善了肾脏病理，增加SOD活性，MDA含量降低，糖尿病大鼠肾组织中p-mTOR/mTOR和p-AKT/AKT比值升高,LC3Ⅱ/Ⅰ比值和p62蛋白表达降低。
结论：肌肽可能通过抑制氧化应激对DM大鼠肾病具有保护作用，激活AKT/mTOR通路，恢复肾脏的自噬。
