Berberine Metabolites Stimulate GLP-1 Secretion by Alleviating Oxidative Stress and Mitochondrial Dysfunction.

Berberine (BBR) is a principal component of Rhizoma coptidis known for its therapeutic potential in treating diseases such as type 2 diabetes mellitus (T2DM) and obesity. Despite the trace levels of BBR in plasma, it's believed that its metabolites play a pivotal role in its biological activities. While BBR is recognized to promote GLP-1 production in intestinal L cells, the cytoprotective effects of its metabolites on these cells are yet to be explored. The present study investigates the effects of BBR metabolites on GLP-1 secretion and the underlying mechanisms. Our results revealed that, out of six BBR metabolites, berberrubine (BBB) and palmatine (PMT) significantly increased the production and glucose-stimulated secretion of GLP-1 in GLUTag cells. Notably, both BBB and PMT could facilitate GLP-1 and insulin secretion and enhance glucose tolerance in standard mice. Moreover, a single dose of PMT could markedly increase plasma GLP-1 and improve glucose tolerance in mice with obesity induced by a high-fat diet. In palmitic acid or TNF[Formula: see text]-treated GLUTag cells, BBB and PMT alleviated cell death, oxidative stress, and mitochondrial dysfunction. Furthermore, they could effectively reverse inflammation-induced inhibition of the Akt signaling pathway. In general, these insights suggest that the beneficial effects of orally administered BBR on GLP-1 secretion are largely attributed to the pharmacological activity of BBB and PMT by their above cytoprotective effects on L cells, which provide important ideas for stimulating GLP-1 secretion and the treatment of T2DM.

Guan Xin Dan Shen formulation protects db/db mice against diabetic cardiomyopathy via activation of Nrf2 signaling.

Guan Xin Dan Shen formulation (GXDSF) is a widely used treatment for the management of coronary heart disease in China and is composed of three primary components: Dalbergiae odoriferae Lignum, Salviae miltiorrhizae Radix et Rhizoma and Panax notoginseng Radix et Rhizoma. However, the potential use of GXDSF for the management of diabetic cardiomyopathy (DCM) has not been previously assessed. The present study aimed to assess the effects of GXDSF on DCM, as well as the underlying mechanism. In the present study, db/db mice were used. Following treatment with GXDSF for 10 weeks, fasting blood glucose, insulin sensitivity, serum lipid levels and cardiac enzyme levels were detected. Cardiac pathological alterations and cardiac function were assessed by performing hematoxylin and eosin staining and echocardiograms, respectively. TUNEL assays were conducted to assess cardiomyocyte apoptosis. Additionally, reverse transcription­quantitative PCR and western blotting were performed to evaluate the expression of apoptosis­associated genes and proteins, respectively. In the model group, the db/db mice displayed obesity, hyperlipidemia and hyperglycemia, accompanied by noticeable myocardial hypertrophy and diastolic dysfunction. Following treatment with GXDSF for 10 weeks, serum triglyceride levels were lower and insulin sensitivity was enhanced in db/db mice compared with the model group, which indicated improvement in condition. Cardiac hypertrophy and dysfunction were also improved in db/db mice following treatment with GXDSF, resulting in significantly increased left ventricular ejection fraction and fractional shortening compared with the model group. Following treatment with metformin or GXDSF, model­induced increases in levels of myocardial enzymes were decreased in the moderate and high dose groups. Moreover, the results indicated that, compared with the model group, GXDSF significantly inhibited cardiomyocyte apoptosis in diabetic heart tissues by increasing Bcl­2 expression and decreasing the expression levels of Bax, cleaved caspase­3 and cleaved caspase­9. Mechanistically, GXDSF enhanced Akt phosphorylation, which upregulated antioxidant enzymes mediated by nuclear factor erythroid 2­related factor 2 (Nrf2) signaling. Collectively, the results of the present study indicated that GXDSF attenuated cardiac dysfunction and inhibited cardiomyocyte apoptosis in diabetic mice via activation of Akt/Nrf2 signaling. Therefore, GXDSF may serve as a potential therapeutic agent for the management of DCM.

[Effect of Guanxin Danshen Formulation on diabetic kidney disease in db/db mice through regulation of Nrf2 pathway].

Diabetic kidney disease(DKD) has become a primary cause of end-stage kidney disease, without any effective treatment available. In this study, we assessed the protective effect of Guanxin Danshen Formulation(GXDSF) on diabetic nephropathy in db/db mice. The db/m and db/db mice were randomly divided into 4 groups: control group, model group, metformin group, and GXDSF group. After 8 weeks' treatment with GXDSF, metformin or normal saline, the mice were sacrificed, and the blood and kidney tissues were collected for the further analysis. Compared with the model group, TG, TCH and LDL levels significantly decreased in the GXDSF group. The results from HE and PAS staining showed that db/db mice exhibited abnormal kidney tissues with increased glomerular volume, basement-membrane thickening and mesangial cell proliferation, which could be significantly alleviated by GXDSF treatment. GXDSF treatment also reduced serum creatinine and BUN. Meanwhile, GXDSF treatment markedly elevated GSH-PX levels, while reduced LDH and MDA levels in the kidney tissues. Western blot assay showed that GXDSF evidently up-regulated protein levels of ERα and p-Akt, and subsequently promoted HO-1 expression mediated by Nrf2. These data collectively indicated that GXDSF protects db/db mice against DN by regulating ERα and Nrf2-mediated HO-1 expression.