Objective

To investigate the effects and molecular mechanism of melatonin (MT) on NF-κB and TGF-β/Smad3 signaling pathways in db/db diabetic mice.

Methods

db/db diabetic mice were divided into five groups treated with melatonin at doses of 50, 100, 200 μg/kg, the urinary concentration was detected by ELISA, renal histology was observed in PAS paining. Mouse mesangial cells were divided into mannitol control group, normal control group, normal control + MT group, high glucose group, high glucose + different concentrations (10, 100, 1000) μmol/L MT group. The proliferation of mesangial cells was detected by EdU kit; the expression of NF-κBp65, ColⅣ and Fn were detected by laser confocal system; the concentrations and mRNA levels of ColⅣ and Fn were detected by ELISA and qRT-PCR. the expressions of ColⅣ, Fn, IκB, p-IκB, TGF-β1, Smad3 and p-Smad3 were detected by Western blot in renal tissues and mesangial cells.

Results

MT treatment could markedly improve the kidney histopathologic lesions. Compared with the db/m mice, 24 h urinary albumin excretion rate (UAER) and the expressions of ColIV, Fn, p-IκB/IκB, NF-κBp65, TGF-β1 and p-Smad3/Smad3 were decreased after melatonin treatment (p <0.05). Compared with the control group, the proliferation function of mesangial cells in high glucose group was significantly enhanced, and the expressions of ColIV, Fn, p-IκB/IκB, NF-κBp65, TGF-β1 and p-Smad3/Smad3 in mesangial cells were significantly up-regulated (p <0.05), and these changes were significantly lowered in MT treatment.

Conclusion

Melatonin can inhibit renal inflammation and fibrosis by inhibiting the NF-κB and TGF-β1/Smad3 signaling pathways, and melatonin may be a promising therapeutic target in diabetic nephropathy.

中文翻译：

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褪黑素通过抑制db / db糖尿病小鼠中的NF-κB和TGF-β1/ Smad3途径改善肾纤维化。

目的

探讨褪黑激素（MT）对db / db糖尿病小鼠NF-κB和TGF-β/ Smad3信号通路的影响及其分子机制。

方法

db / db糖尿病小鼠分为50、100、200μg/ kg褪黑素治疗的五组，通过ELISA检测尿液浓度，观察PAS疼痛的肾脏组织学。小鼠肾小球系膜细胞分为甘露醇对照组，正常对照组，正常对照组+ MT组，高糖组，高糖+不同浓度（10、100、1000）μmol/ L MT组。用EdU试剂盒检测肾小球系膜细胞的增殖。激光共聚焦法检测NF-κBp65，ColⅣ和Fn的表达。ELISA和qRT-PCR检测ColⅣ和Fn的浓度和mRNA水平。Western blot检测肾组织和系膜细胞中ColⅣ，Fn，IκB，p-IκB，TGF-β1，Smad3和p-Smad3的表达。

结果

MT治疗可明显改善肾脏的组织病理学损害。与db / m小鼠相比，褪黑素治疗后24小时尿白蛋白排泄率（UAER）和ColIV，Fn，p-IκB/IκB，NF-κBp65，TGF-β1和p-Smad3 / Smad3的表达降低（p＜0.05）。与对照组相比，高糖组肾小球系膜细胞的增殖功能明显增强，肾小球膜细胞中ColIV，Fn，p-IκB/IκB，NF-κBp65，TGF-β1和p-Smad3 / Smad3的表达明显上调（p <0.05），并且这些变化在MT治疗中显着降低。

结论

褪黑素可通过抑制NF-κB和TGF-β1/ Smad3信号通路抑制肾脏炎症和纤维化，而褪黑素可能是糖尿病肾病的有希望的治疗靶点。