Apoptosis in pancreatic β-cells is induced by arsenic and atorvastatin in Wistar rats with diabetes mellitus type 2

Biochanin‑A as SIRT‑1 modulator in preventing statin‑associated diabetogenesis: An in vitro study

The widespread use of statin therapy for hypercholesterolemia has raised concerns due to its associated risk of inducing diabetes. Biochanin-A (BA), an isoflavone, exhibits potential in preventing diabetes and hyperlipidemia, yet its efficacy in mitigating statin-induced diabetes remains unexplored. This gap prompts a crucial inquiry: Can BA reduce the risk of diabetes associated with statin therapy? The present study investigated the molecular mechanisms behind atorvastatin's diabetogenic nature and evaluated the potential of BA to counteract these effects. Insulin resistance was assessed using L6 skeletal muscle cells and pancreatic beta cell apoptosis in MIN-6 cells. Our hypothesis posits that atorvastatin exacerbates free fatty acid accumulation, leading to the downregulation of sirtuin-1 (SIRT-1) and decreased uncoupling protein (UCP) 3 expression, culminating in insulin resistance. Conversely, BA is assumed to positively modulate SIRT-1 and downregulate UCP2, thus offering a protective effect. In vitro studies using L6 and MIN-6 cells revealed that BA has increased cell viability and shown optimal protection against the toxicity induced by atorvastatin in both cell lines at different concentrations. BA effectively inhibited the reduction in glucose uptake caused by atorvastatin. Pre-treatment with BA upregulated proteins that are involved in the insulin-signaling pathway and reversed the expression levels of UCPs induced by atorvastatin. BA also enhanced insulin release, preserved mitochondrial function, and prevented atorvastatin-induced apoptosis. Furthermore, BA improved SIRT-1 expression, potentially through the nicotinamide phospho-ribosyl-transferase-nicotinamide adenine dinucleotide + SIRT1-pathway, revealing that BA may play a role in modulating cellular processes in statin-associated SIRT-1 downregulation. BA can be considered a promising molecule to counteract statin-induced diabetes, suggesting a prospective therapeutic role in enhancing the safety profile of statin therapy. This research lays the groundwork for future clinical evaluations of BA as an adjunctive treatment for patients at risk of statin-induced diabetes.

Hypoglycemic Effect of the N-Butanol Fraction of Torreya grandis Leaves on Type 2 Diabetes Mellitus in Rats through the Amelioration of Oxidative Stress and Enhancement of β-Cell Function

Materials and Methods

Sprague-Dawley rats were randomly divided into six groups: control, T2DM, metformin, high-dose BFTL (800 mg/kg), middle-dose BFTL (400 mg/kg), and low-dose BFTL (200 mg/kg). After 4 weeks of BFTL treatment, the correlations of serum indicators with protein expression in tissue were determined, and pathological changes in the liver, kidneys, and pancreas were analyzed.

Results

Compared with the results in the T2DM group, serum fasting blood glucose, triglyceride, total cholesterol, malondialdehyde, alanine aminotransferase, and aspartate aminotransferase levels were significantly decreased (p < 0.05), whereas superoxide dismutase and glutathione peroxidase levels were significantly increased (p < 0.05) in the high-, middle-, and low-dose BFTL groups. The treatment also improved oral glucose tolerance. In addition, the pathological changes of the liver, kidney, and pancreas were improved by BFTL treatment. Cytochrome and caspase-3 expression in pancreatic was significantly decreased (p < 0.05) by BFTL treatment, whereas the Bcl-2/Bax ratio was significantly increased (p < 0.05). Discussion and Conclusion. BFTL exerted significant hypoglycemic effect on T2DM model rats, and its mechanism involved the suppression of blood glucose levels and oxidative stress by improving the metabolism of blood lipids and antioxidant capacity, boosting β-cell function, and inhibiting β-cell apoptosis.

Increased urinary arsenic concentration in newly diagnosed type 2 diabetes mellitus: a gender-independent, smoking-dependent exposure biomarker in older adults in Tehran

Arsenic is ranked in the top ten environmental toxicants but its impact on type 2 diabetes mellitus (T2DM) and its association with other human health effects is contradictory. We aimed in this study to compare the urinary arsenic concentration (u As) in older age adults (> 40 years) and their T2DM subgroup in an age and gender-matched case control study to find the association of u As with, diet, oxidative stress, smoking, anthropometric factors, and lifestyle in our study participants. Face-to-face interviews based on structured questionnaires were conducted on 200 female and male volunteers (100 cases and 100 control). Considering the exclusion criteria, u As concentration and serum biomarkers of oxidative stress (malondialdehyde, superoxide dismutase, catalase) of 30 newly diagnosed T2DM and 30 control were determined by ICP-mass analysis and ELISA reader respectively. Despite the similarities in sociodemographic, diet, and lifestyle factors in males and females and their T2DM subgroups, a 4 times difference in u As levels between T2DM (93.7 ng/L (32)) and their healthy counterparts (23.7 ng/L (2.3)) without meaningful associations with gender, age, BMI, diet, and lifestyle was observed. Mean u As concentration in total population of smokers was significantly higher than non-smokers ((119 ng/L vs. 22.5 ng/L (p = 0.03)) and oxidative stress markers were not significantly higher in T2DM smokers than non-smokers. Chronic arsenic exposure through smoking could be contributed to the incidence of T2DM in older age adults. Oxidative stress markers were not significantly increased in smoker subgroup compared with non-smokers but except smoking pattern, other variables did not affect u As concentration. Precautionary measure to reduce the exposure of people with this element is recommended to prevent the arsenic-induced T2DM in human populations.

Ameliorative Effect and Mechanism of the Purified Anthraquinone-Glycoside Preparation from Rheum Palmatum L. on Type 2 Diabetes Mellitus

Rheum palmatum L. is a traditional Chinese medicine with various pharmacological properties, including anti-inflammatory, antibacterial, and detoxification effects. In this study, the mechanism of the hypoglycemic effect of purified anthraquinone-Glycoside from Rheum palmatum L. (PAGR) in streptozotocin (STZ) and high-fat diet induced type 2 diabetes mellitus (T2DM) in rats was investigated. The rats were randomly divided into normal (NC), T2DM, metformin (Met), low, middle (Mid), and high (Hig) does of PAGR groups. After six weeks of continuous administration of PAGR, the serum indices and tissue protein expression were determined, and the pathological changes in liver, kidney, and pancreas tissues were observed. The results showed that compared with the type 2 diabetes mellitus group, the fasting blood glucose (FBG), total cholesterol (TC), and triglyceride (TG) levels in the serum of rats in the PAGR treatment groups were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) levels were noticeably increased. The expression of Fas ligand (FasL), cytochrome C (Cyt-c), and caspase-3 in pancreatic tissue was obviously decreased, and the pathological damage to the liver, kidney, and pancreas was improved. These indicate that PAGR can reduce oxidative stress in rats with diabetes mellitus by improving blood lipid metabolism and enhancing their antioxidant capacity, thereby regulating the mitochondrial apoptotic pathway to inhibitβ-cell apoptosis and improve β-cell function. Furthermore, it can regulate Fas/FasL-mediated apoptosis signaling pathway to inhibit β-cell apoptosis, thereby lowering blood glucose levels and improving T2DM.

Improvement of high-glucose and insulin resistance of chromium malate in 3T3-L1 adipocytes by glucose uptake and insulin sensitivity signaling pathways and its mechanism

Previous study has revealed that chromium malate could improve insulin resistance and the regulation of fasting blood glucose in type 2 diabetic rats. This study was designed to investigate the effect of chromium malate on hypoglycemic and improve insulin resistance activities in 3T3-L1 adipocytes with insulin resistance and investigate the acting mechanism. The result indicated that chromium malate exhibited direct hypoglycemic activity in vitro. Compared with the model group, chromium malate could significantly promote the expression levels of GLUT-4, Akt, Irs-1, PPARγ, PI3K and p38-MAPK and their mRNA, increase p-AKT/AKT level, AKT and AMPKβ1 phosphorylation and reduce Irs-1 phosphorylation and p-Irs-1/Irs-1 level in 3T3-L1 adipocytes (p < 0.05). Chromium malate is more effective in regulating the proteins and mRNA expressions than those of chromium trichloride and chromium picolinate. Compared to the model group, pretreatment with the specific p38-MAPK inhibitor completely inhibited the GLUT-4 and Irs-1 proteins and mRNA expressions induced by the chromium malate. In conclusion, chromium malate had a beneficial influence on improvement of controlling glucose levels and insulin resistance in 3T3-L1 adipocytes with insulin resistance by regulating proteins productions and genes expressions in glucose uptake and insulin sensitivity signaling pathways.

Chromium malate could increase the related protein and mRNA levels in 3T3-L1 adipocytes with insulin resistant. Pretreatment with the inhibitor completely/partially inhibited the GLUT-4 and Irs-1 proteins and mRNA expression compared to model group.