Aims: The objective of this study was to explore the effects of epigallocatechin-3-gallate (EGCG) on type 2 diabetes mellitus (T2DM). Main methods: Male Sprague–Dawley rats were allocated into six groups. The control group received a conventional diet. The diabetic group received a high-sucrose high-fat (HSHF) diet for 4 weeks and then was fasted and injected with streptozotocin (STZ); subsequently, the rats received a HSHF diet for another 4 weeks to develop diabetes. The four treatment groups were diabetic rats that received intragastric metformin (500 mg/kg/day) or EGCG (25, 50, and 100 mg/kg/day) for 10 weeks. All groups except the control group received a HSHF diet throughout the experiment. Several biochemical parameters such as fasting blood glucose (FBG), postprandial blood glucose (PBG), liver glycogen, muscle glycogen, fasting serum insulin (FSI), homeostasis model of insulin resistance (HOMA-IR), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), free fatty acids (FFA), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured to assess the effects of EGCG on glycemic control, insulin resistance, lipid profile, and oxidative stress. Furthermore, oxidative stress in pancreatic islet β cells was detected by dihydroethidium staining. Key findings: A HSHF diet and STZ injection induced T2DM, as indicated by changed blood glucose and body weight, which was accompanied by insulin resistance, an altered lipid profile, and oxidative stress. Interestingly, EGCG treatment dose-dependently recovered these indexes. Significance: EGCG successfully ameliorated glycemic control and insulin sensitivity while reducing the lipid profile and oxidative stress in a T2DM rat model.
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Endothelial dysfunction is the pathological basis of atherosclerosis. Incomplete understanding of endothelial dysfunction etiology has impeded drug development for this devastating disease despite the currently available therapies. Floralozone, an aroma flavor, specifically exists in rabbit ear grass. Recently, floralozone has been demonstrated to inhibit atherosclerosis, but the underlying mechanisms are undefined. The present study was undertaken to explore whether floralozone pharmacologically targets endothelial dysfunction and therefore exerts therapeutic effects on atherosclerosis. The Na+/H+ exchanger 1 (NHE1), a channel protein, plays a vital role in atherosclerosis. Whether NHE1 is involved in the therapeutic effects of floralozone on endothelial dysfunction has yet to be further answered. By performing oil red staining and hematoxylin–eosin staining, vascular functional study, and oxidative stress monitoring, we found that floralozone not only reduced the size of carotid atherosclerotic plaque but also prevented endothelial dysfunction in atherosclerotic rats. NHE1 expression was upregulated in the inner membrane of carotid arteries and H2O2-induced primary rat aortic endothelial cells. Inspiringly, floralozone prevented the upregulation of NHE1 in vivo and in vitro. Notably, the administration of NHE1 activator LiCl significantly weakened the protective effect of floralozone on endothelial dysfunction in vivo and in vitro. Our study demonstrated that floralozone exerted its protective effect on endothelial dysfunction in atherosclerosis by ameliorating NHE1. NHE1 maybe a drug target for the treatment of atherosclerosis, and floralozone may be an effective drug to meet the urgent needs of atherosclerosis patients by dampening NHE1.
Aims: This study aimed to evaluate the effects and mechanisms of tertiary butylhydroquinone (TBHQ) on insulin resistance (IR) and diabetic liver steatosis. Methods: Male ApoE-/- mice were received streptozocin (STZ) injection and a high-sugar-high-fat diet to form type 2 diabetes mellitus (T2DM). Then, the mice were given TBHQ for six weeks. Body weight, fasting blood-glucose (FBG), postprandial blood glucose (PBG), insulin and oral glucose tolerance test (OGTT) were detected on all the mice. Hematoxylin-eosin staining and western-blot were performed to detect the morphological structure and the target proteins expression in liver tissues. In vitro, HepG2 cells were induced by HClO and insulin to develop IR. Western-blot was used to evaluate the related proteins expression. Hoechst staining was conducted to measure cell apoptosis. Results: Mice that received STZ injection and a high-sugar-high-fat diet developed T2DM. TBHQ reduced blood glucose level, improved glucose tolerance, alleviated liver steatosis in diabetic mice. Moreover, TBHQ significantly increased AMPKα2, GLUT4 and GSK3β expression, up-regulated PI3K and AKT phosphorylation level in diabetic mice liver. Notably, TBHQ down-regulated HClO and insulin-induced cell IR and inhibited cell apoptosis via AMPKα2/PI3K/AKT pathway. Conclusion: TBHQ alleviated IR and liver steatosis in T2DM mice and the mechanism may relate to AMPKα2/PI3K/AKT pathway.
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