Objective Hepatic insulin resistance is a major initiating factor for type 2 diabetes mellitus. In previous study, Gegen Qinlian Decoction containing berberine could enhance hepatic insulin sensitivity by SIRT1-dependent deacetylation of FOXO1. However, it is not clear whether berberine also can improve hepatic insulin sensitivity by SIRT1/FOXO1 pathway. This study aimed to evaluate the efficacy of berberine for improving hepatic insulin resistance and the possible molecular mechanisms involved. Methods In vitro, HepG2 cells were induced with palmitic acid, and glycogen synthesis was examined. In vivo, a high-fat diet (HFD)-fed mouse model was established, and metabolic parameters were assessed. The expressions of miR-146b and sirtuin 1 (SIRT1) in liver were also examined. The relationship between miR-146b and SIRT1 was examined by the dual-luciferase reporter gene assay. Results Serum biochemical parameters, such as glucose and HOMA-IR index, were increased in HFD mice; miR-146b and SIRT1 were abnormally expressed in HFD mice and palmitic acid-treated HepG2 cells. Interestingly, berberine reduced body weight and caused a significant improvement in glucose tolerance and HOMA-IR index without altering food intake in mice. Overexpression of miR-146b abolished the protective effect of berberine on palmitic acid-induced impaired glycogen synthesis in HepG2 cells. Luciferase assay showed that miR-146b directly targeted SIRT1. Conclusion The present findings suggest that berberine could attenuate hepatic insulin resistance through the miR-146b/SIRT1 pathway, which may represent a potential therapeutic target for the prevention and treatment of metabolic diseases, particularly diabetes.

BackgroundGegen qinlian decoction (GGQLD) is a form of traditional Chinese medicine used for hundreds of years for its efficacy in treating diabetes. However, the mechanisms underlying the therapeutic effects of GGQLD on diabetes are still not clear. We aimed to evaluate the effect of GGQLD on hepatic insulin resistance (IR) through silent information regulator1 (SIRT1)/forkhead box O1 (FOXO1) in an IR mouse model.Material/MethodsA high-fat diet (HFD) mouse model was established and GGQLD was administrated by oral gavage. Metabolic parameters were detected, including body weights, triglyceride, fasting glucose, fasting insulin and HOMA-IR index, glucose intolerance, and insulin resistance. HE-stained sections were used to observe the histopathology of liver tissue. For in vitro study, GGQLD-medicated serum was used to treat palmitic acid-stimulated HepG2 cells. The glycogen synthesis and downstream SIRT1/FOXO1 signaling pathways were examined. Specific siRNAs were used to knock down SIRT1 in HepG2 cells.ResultsGGQLD administration significantly decreased body weights, triglyceride level, fasting glucose level, fasting insulin level, and HOMA-IR index, and improved IR in HFD mice. GGQLD enhanced SIRT1 expression and suppressed the expression of Ac-FOXO1 in liver tissues. Further, GGQLD-medicated serum promoted SIRT1 upregulation and suppressed Ac-FOXO1 levels in palmitate-stimulated HepG2 cells. GGQLD-medicated serum also increased the protein expression of PPARγ and reduced the expression of FABP4 in palmitate-stimulated HepG2 cells.ConclusionsWe found that GGQLD alleviates insulin resistance through SIRT1-dependent deacetylation of FOXO1.

Background: To evaluate the effect of metformin therapy on decreasing benign thyroid nodule volume in subjects with insulin resistance (IR).Method: Randomized controlled trials (RCTs) and self-controlled trials for the meta-analysis published, before January 31, 2018 were selected from the PubMed, Cochrane Library, Embase, Web of Science, Chinese Biomedical Literature Database, National Knowledge Infrastructure, WANFANG and VIP Database. Pooled standard mean difference with 95% confidence interval was estimated by fixed- or random-effects model depending on heterogeneity. The risk of bias using the Cochrane Collaboration's tool was used to assess the quality of the RCTs contained. The quality of self-controlled studies was evaluated using the Methodological index for non-randomized studies (MINORS) method.Results: 7 studies (3 RCTs and 4 prospective self-controlled studies) with 240 patients were considered to be appropriate for the meta-analysis. The results of the meta-analysis indicated that the volume of thyroid nodule decreased significantly after metformin therapy (SMD −0.62, 95% CI −0.98 ~ −0.27). 6 studies reported the changes of the level of TSH. TSH levels decreased significantly after metformin therapy (SMD −0.27, 95% CI −0.47 ~ −0.07). The pooled data indicated an increase in FT3 level, and an unchanged FT4 level after metformin therapy (FT3, SMD 0.25, 95% CI 0.05 ~ 0.45; FT4, SMD −0.07, 95% CI −0.27 ~ 0.13). HOMA-IR levels decreased significantly after metformin therapy based on the pooled results of 3 RCTs and 3 prospective self-controlled studies (SMD −1.08, 95% CI −1.69 ~ −0.47).Conclusion: The meta-analysis demonstrated that metformin was safe and useful in shrinking benign thyroid nodules volume, improving thyroid function and IR. A large number of high-quality prospective studies still need to be carried out.

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