Sex differences in oxidative stress level and antioxidative enzymes expression and activity in obese pre-diabetic elderly rats treated with metformin or liraglutide

Efficacy of metformin combined with liraglutide on the glucose and lipid metabolism, vascular endothelial function, and oxidative stress of patients with T2DM and metabolic syndrome

Objective

This study evaluates the impact of metformin combined with liraglutide on the glucose and lipid metabolism, oxidative stress, and vascular endothelium of patients with type-2 diabetes mellitus (T2DM) and metabolic syndrome.

Methods

Medical records of 78 patients with T2DM and metabolic syndrome, admitted to Caoxian People's Hospital from July 2021 to July 2022, were retrospectively analysed. Thirty five patients were treated with metformin (control group), and 43 patients were treated with metformin combined with liraglutide (observation group). Indexes of glucose and lipid metabolism, function of vascular endothelium and the oxidative stress of both groups were compared before and after the treatment.

Results

There was a significant decrease in the levels of fasting plasma glucose (FPG), Glycosylated Hemoglobin A1c (HbA1c), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), systolic blood pressure (SBP), diastolic blood pressure (DBP) and waist circumference in both groups three months after the treatment, These indexes were significantly lower in the observation group compared to the control group (P<0.05). High-density lipoprotein cholesterol (HDL-C) levels were higher in the observation group (P<0.05). There was a significant improvement in the levels of nitric oxide (NO), endothelin-1 (ET-1), superoxide dismutase (SOD), and malondialdehyde (MDA) after the treatment, and these indexes were markedly better in the observation group compared to the control group (P<0.05).

Conclusions

Metformin combined with liraglutide treatment is associated with better outcomes than metformin alone in patients with T2DM and metabolic syndrome. Combined treatment results in improved glucose and lipid metabolism, vascular endothelial function, and oxidative stress index values.

A novel anti-obesity mechanism for liraglutide by improving adipose tissue leptin resistance in high-fat diet-fed obese mice

Liraglutide has been approved for the treatment of obesity in the past few years. Both oxidative stress and leptin resistance are the critical drivers of obesity. The present study investigated the mechanism of liraglutide protection against obesity by ameliorating leptin resistance and oxidative stress. Male C57BL/6J mice were fed a high-fat diet (HFD) and subcutaneously injected with 200 μg/kg/d liraglutide for 20 weeks. Body weight, fat mass, serum levels of leptin, insulin, and superoxide dismutase (SOD) activities were measured. In addition, glucose and insulin tolerance tests were performed. The expressions of leptin, its signaling genes, and antioxidant enzymes were detected using RT-qPCR and western blot methods in liver and white adipose tissue (WAT) of mice. The results depicted that liraglutide treatment significantly slowed weight gain of body, reduced the fat mass, ameliorated glucose and lipid metabolism, and hepatic steatosis in HFD-fed obese mice. Further study demonstrated that liraglutide treatment resulted in decreased serum levels and the transcript levels of leptin as well as leptin signaling inhibitory regulators. However, it increased leptin receptor expression and the phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) in WAT (p < 0.05). In addition, the antioxidant enzyme expression was elevated in both liver and WAT of liraglutide-treated mice (p < 0.05). In conclusion, liraglutide conspicuously prevented obesity and ameliorated glucose and lipid metabolism in obese mice through a novel mechanism that improves peripheral leptin resistance in WAT and enhance the antioxidant enzyme expression in both liver and WAT.

Metformin's Impact on the Microvascular Response to Insulin

Metformin improves insulin's action on whole-body glucose metabolism in various insulin-resistant populations. The detailed cellular mechanism(s) for its metabolic actions are multiple and still incompletely understood. Beyond metabolic actions, metformin also impacts microvascular function. However, the effects of metformin on microvascular function and microvascular insulin action specifically are poorly defined. In this mini-review, we summarize what is currently known about metformin's beneficial impact on both microvascular function and the microvascular response to insulin while highlighting methodologic issues in the literature that limit straightforward mechanistic understanding of these effects. We examine potential mechanisms for these effects based on pharmacologically dosed studies and propose that metformin may improve human microvascular insulin resistance by attenuating oxidative stress, inflammation, and endothelial dysfunction. Finally, we explore several important evidence gaps and discuss avenues for future investigation that may clarify whether metformin's ability to improve microvascular insulin sensitivity is linked to its positive impact on vascular outcomes.

Effects of age and gender on the redox homeostasis of morbidly obese people

Obesity is a chronic disease of complex etiology. Recent evidence suggests that obesity is caused by inflammation of adipose tissue leading to metabolic disorders, cardiovascular disease and cancer. This is the first study to evaluated the effects of age and gender on redox homeostasis, glutathione metabolism, and oxidative damage to plasma/serum lipids and proteins in morbidly obese patients. The study included 120 (60 men and 60 women) morbidly obese patients with class 3 obesity (BMI > 40 kg/m2), classified into three groups depending on age: 20-39 years (n = 20), 40-59 years (n = 20) and 60 years or older (n = 20). The number of patients was calculated a priori based on our previous experiment. We observed a reduction in serum activity of antioxidant enzymes (↓SOD) and plasma concentration of non-enzymatic antioxidants (↓GSH) in obese patients compared to the lean controls, which further decreased with age. Redox status (↑TAC, ↑TOS and ↓OSI) in morbidly obese men and women was shifted towards oxidation. Moreover, lipid (↑MDA and ↑LOOH) and protein (↑AOPP, ↑AGE and ↑Amadori products) damage products of oxidation and nitrosylation/nitration (↑total NO, ↑S-nitrosothiols, ↑peroxynitrite and ↑nitrotyrosine) were elevated in both genders of morbidly obese patients and were higher in the elderly. Interestingly, the concentrations of oxidative and nitrosative stress markers were generally higher in obese men compared to obese women at the same age. Summarizing, we showed that the total antioxidant/oxidant potential of obese patients is significantly increased and shifted towards oxidation. Obese patients have increased lipid and protein oxidation, glycation and nitration as compared to the lean controls. Disturbances in redox homeostasis increase with age in obese patients. Oxidative and nitrosative stress are more intense in men than in women at the same age.