Tert-butylhydroquinone abrogates fructose-induced insulin resistance in rats via mitigation of oxidant stress, NFkB-mediated inflammation in the liver but not the skeletal muscle of high fructose drinking rats

The effect of 21% fructose drinking water (FDW) (w/v) on some parameters of metabolic syndrome, hepatic, and skeletal muscular histology of rats was studied using standard techniques. Twenty male albino rats were divided into four groups of 5 rats each in this in vivo study. Group I received distilled water, group 2 received FDW, group 3 received FDW and metformin (300 mg/kg body weight daily, orally), group 4 received FDW and 1% tert-butylhydroquinone feed. FDW changed the serum leptin, triacylglycerol, very low-density lipoprotein, and C-reactive protein levels of the rats, inducing hypertriglyceridemia, oxidative stress, and inflammation in their liver (but not the skeletal muscle) and insulin resistance which were modulated with metformin and tBHQ as corroborated by liver and muscle histology. The study reveals the potentials of metformin and tBHQ in mitigating hepatic and skeletal muscular morphological changes arising from exposure to high fructose drinks. PRACTICAL APPLICATIONS: There has been an increase in the global consumption of fructose (either as a sweetner in beverages or soft and carbonated drinks) in the last few decades and this has been positively correlated with the global increase in metabolic complications. Regular intake of fructose contributes to the pathogenesis of lipid disorders, oxidant stress, and chronic inflammation, which are linked with the metabolic syndrome components (MetS) (obesity, insulin resistance, and cardiovascular diseases) as well as increased morbidity and mortality. Given that the approaches that have been applied to treat the MetS have not been able to totally arrest it, currenty study which showed that tBHQ abrogated fructose-induced insulin resistance, dyslipidemia, hepatic, and skeletal muscular pathology in the rats places tBHQ in the spotlight as a nutraceutical that could be of relevance in mitigating high dietary fructose-induced hepatic and skeletal muscular pathology.

Antidiabetic drugs and oxidized low-density lipoprotein: A review of anti-atherosclerotic mechanisms

Cardiovascular disease is one of the leading causes of mortality globally. Atherosclerosis is an important step towards different types of cardiovascular disease. The role of oxidized low-density lipoprotein (oxLDL) in the initiation and progression of atherosclerosis has been thoroughly investigated in recent years. Moreover, clinical trials have established that diabetic patients are at a greater risk of developing atherosclerotic plaques. Hence, we aimed to review the clinical and experimental impacts of various classes of antidiabetic drugs on the circulating levels of oxLDL. Metformin, pioglitazone, and dipeptidyl peptidase-4 inhibitors were clinically associated with a suppressive effect on oxLDL in patients with impaired glucose tolerance. However, there is an insufficient number of studies that have clinically evaluated the relationship between oxLDL and newer agents such as agonists of glucagon-like peptide 1 receptor or inhibitors of sodium-glucose transport protein 2. Next, we attempted to explore the multitude of mechanisms that antidiabetic agents exert to counter the undesirable effects of oxLDL in macrophages, endothelial cells, and vascular smooth muscle cells. In general, antidiabetic drugs decrease the uptake of oxLDL by vascular cells and reduce subsequent inflammatory signaling, which prevents macrophage adhesion and infiltration. Moreover, these agents suppress the oxLDL-induced transformation of macrophages into foam cells by either inhibiting oxLDL entrance, or by facilitating its efflux. Thus, the anti-inflammatory, anti-oxidant, and anti-apoptotic properties of antidiabetic agents abrogate changes induced by oxLDL, which can be extremely beneficial in controlling atherosclerosis in diabetic patients.

THE EFFECT OF MYOINOSITOL AND METFORMIN ON CARDIOVASCULAR RISK FACTORS IN WOMEN WITH POLYCYSTIC OVARY SYNDROME: A RANDOMIZED CONTROLLED TRIAL

CONTEXT

Cardiovascular risk is increased in women with polycystic ovary syndrome (PCOS). Do insulin sensitizing agents such as metformin (MET) and myoinositol (MI) ameliorate biomarkers of cardiovascular risk?

OBJECTIVE

To compare the effects of MET and MI on blood pressure, lipid profile and high sensitive C-reactive protein (hs-CRP) in women with PCOS in respect to their body mass index (BMI).

DESIGN

Open label, parallel randomized, single center study.

SUBJECTS AND METHODS

Sixty six women with PCOS (33 normal-weight and 33 overweight/obese) were randomized to either MI (4 g/day) or MET (1500 mg/day) for a period of 6 months. Serum concentration of hormones, lipid profile, oxidized LDL (ox-LDL), hs-CRP, blood pressure measurement and clinical assessment of BMI, waist circumference (WC) and Ferriman Gallwey score (FG score) were performed before and after treatment.

RESULTS

Thirty patients in each group completed the trial. Compared with MET, MI significantly decreased diastolic blood pressure (DBP) (p=0.036) and significantly increased serum hs-CRP (p=0.043). No differences between groups in total cholesterol (TC), HDL-cholesterol, LDL-cholesterol, ox-LDL and triglycerides were reported after 6 months. Treatment with MI reduced BMI (p=0.037), WC (p=0.005), DBP (p=0.021) and TC (p=0.008). During MET treatment a significant decrease in BMI (p=0.005), WC (p=0.004), FG score (p=0.001), testosterone (p=0.013) and free androgen index (FAI) (p=0.006) was observed.

CONCLUSIONS

Our study showed an advantage of MI in reduction of DBP and TC thus predicting favorable metabolic and cardiovascular outcomes in PCOS women. MET more effectively decrease indices of hyperandrogenism.

The evidence of metabolic-improving effect of metformin in Ay/a mice with genetically-induced melanocortin obesity and the contribution of hypothalamic mechanisms to this effect

In diet-induced obesity, metformin (MF) has weight-lowering effect and improves glucose homeostasis and insulin sensitivity. However, there is no information on the efficiency of MF and the mechanisms of its action in melanocortin-type obesity. We studied the effect of the 10-day treatment with MF at the doses of 200, 400 and 600 mg/kg/day on the food intake and the metabolic and hormonal parameters in female C57Bl/6J (genotype A^y/a) agouti-mice with melanocortin-type obesity, and the influence of MF on the hypothalamic signaling in obese animals at the most effective metabolic dose (600 mg/kg/day). MF treatment led to a decrease in food intake, the body and fat weights, the plasma levels of glucose, insulin and leptin, all increased in agouti-mice, to an improvement of the lipid profile and glucose sensitivity, and to a reduced fatty liver degeneration. In the hypothalamus of obese agouti-mice, the leptin and insulin content was reduced and the expression of the genes encoding leptin receptor (LepR), MC₃- and MC₄-melanocortin receptors and pro-opiomelanocortin (POMC), the precursor of anorexigenic melanocortin peptides, was increased. The activities of AMP-activated kinase (AMPK) and the transcriptional factor STAT3 were increased, while Akt-kinase activity did not change from control C57Bl/6J (a/a) mice. In the hypothalamus of MF-treated agouti-mice (10 days, 600 mg/kg/day), the leptin and insulin content was restored, Akt-kinase activity was increased, and the activities of AMPK and STAT3 were reduced and did not differ from control mice. In the hypothalamus of MF-treated agouti-mice, the Pomc gene expression was six times higher than in control, while the gene expression for orexigenic neuropeptide Y was decreased by 39%. Thus, we first showed that MF treatment leads to an improvement of metabolic parameters and a decrease of hyperleptinemia and hyperinsulinaemia in genetically-induced melanocortin obesity, and the specific changes in the hypothalamic signaling makes a significant contribution to this effect of MF.

Metformin and ascorbic acid combination therapy ameliorates type 2 diabetes mellitus and comorbid depression in rats

Diabetes mellitus and depression are the common comorbid disorders affecting humans worldwide. There is an unmet need to develop therapeutic strategies to treat both diabetes mellitus and comorbid depression. The present study evaluated the effectiveness of metformin and ascorbic acid against type 2 diabetes mellitus and comorbid depression in rats. Four groups of diabetic rats were orally administered with vehicle (1mL/kg), metformin (25mg/kg), ascorbic acid (25mg/kg), or combination of metformin (25mg/kg) and ascorbic acid (25mg/kg) for 11 consecutive days. Diabetes was induced by single-dose administration of streptozotocin (65mg/kg, i.p.) with nicotinamide (120mg/kg, i.p.). Comorbid depression was induced by five inescapable foot-shocks (2mA, 2ms duration) at 10s intervals on days 1, 5, 7, and 10. One group of healthy rats received only vehicles to serve as nondiabetic control group. On day 11, animals were sacrificed, and blood and brain samples were collected from each rat following forced swim test. Plasma glucose, insulin, and corticosterone levels were estimated in plasma. The levels of monoamines, proinflammatory cytokines, and oxidative stress were measured in prefrontal cortex. The combination therapy significantly reduced immobility period, glucose, and corticosterone levels relative to diabetes with comorbid depression group. Furthermore, the combination therapy increased the levels of insulin and monoamines, and caused a significant reductions in oxidative stress and proinflammatory cytokines. In conclusion, the present study revealed that metformin and ascorbic acid combination therapy could be a potential strategy to treat type 2 diabetes mellitus and comorbid depression.

Antioxidant properties of drugs used in Type 2 diabetes management: could they contribute to, confound or conceal effects of antioxidant therapy?

Objectives: This is a narrative review, investigating the antioxidant properties of drugs used in the management of diabetes, and discusses whether these antioxidant effects contribute to, confound, or conceal the effects of antioxidant therapy.

Methods: A systematic search for articles reporting trials, or observational studies on the antioxidant effect of drugs used in the treatment of diabetes in humans or animals was performed using Web of Science, PubMed, and Ovid. Data were extracted, including data on a number of subjects, type of treatment (and duration) received, and primary and secondary outcomes. The primary outcomes were reporting on changes in biomarkers of antioxidants concentrations and secondary outcomes were reporting on changes in biomarkers of oxidative stress.

Results: Diabetes Mellitus is a disease characterized by increased oxidative stress. It is often accompanied by a spectrum of other metabolic disturbances, including elevated plasma lipids, elevated uric acid, hypertension, endothelial dysfunction, and central obesity. This review shows evidence that some of the drugs in diabetes management have both in vivo and in vitro antioxidant properties through mechanisms such as scavenging free radicals and upregulating antioxidant gene expression.

Conclusion: Pharmaceutical agents used in the treatment of type 2 diabetes has been shown to exert an antioxidant effect..

An Overview of Metformin and Implications in the Workplace

Diabetes mellitus is expensive; one of the top 10 most costly health concerns for employers. Individuals with type 2 diabetes mellitus (T2DM) who achieve glycemic targets through healthy lifestyles and appropriate glucose-lowering agents lessen diabetes-related complications. The purpose of this article is to provide a brief review of a first-line agent used in treating T2DM, the biguanide metformin hydrochloride. Implications for health providers who assist employees who use metformin also are addressed.

Appearance of leptin-HSP70 correlation, in type 2 diabetes

In vitro and in vivo studies have shown conflicting results regarding heat shock protein (HSP) and leptin correlation. More importantly both HSP70 and leptin are correlated with C reactive proteins. The purpose of the present study was to study the correlation between serum HSP70 and leptin levels in patients with type 2 diabetes stratified according to gender. We performed a cross sectional study on the established groups of patients with type 2 diabetes defined as 1: patients with long standing diabetes for more than 3 years; and 2: patients with newly diagnosed diabetes within recent 6 months who were not on any glucose lowering treatment other than by dietary means alone and 3: healthy controls. Patients with long standing diabetes had higher HSP70, HbA1c and triglyceride than controls. Serum leptin levels were significantly lower in patients with newly diagnosed diabetes. Women with type 2 diabetes had higher leptin levels compared to men, both before and after treatment. We showed a positive correlation between leptin and HSP70 levels in women with type 2 diabetes. The correlation was strongest in women with newly diagnosed diabetes (r = 0.59) and was attenuated in women who were on treatment (r = 0.3). The significance of this correlation was only observed in women with type 2 diabetes. There was no correlation between leptin and HSP70 in men. The positive correlation between leptin and HSP is observed in chronic inflammation such as type 2 diabetes. It could be hypothesized that the observed correlation between serum HSP70 and leptin implies a higher state of chronic inflammation.

Effect of combined treatment with clozapine and metformin on fasting blood glucose, insulin level, and expression of the glucose transporter-2 (GLUT2) in Sprague-Dawley rats

BACKGROUND

Antipsychotic medications can cause an increase in blood glucose and the development of type II diabetes. Metformin may ameliorate these side effects.

OBJECTIVE

Assess whether or not metformin reduces the abnormalities in glucose metabolism that occur with use of the antipsychotic clozapine.

METHODS

Eighteen adult Sprague-Dawley (SD) rats were divided into three groups that were intragastrically administered saline, clozapine (20 mg/kg), or a combination of clozapine (20 mg/kg) and metformin (78 mg/kg) for 28 days. Fasting blood glucose was assessed at baseline and every seven days thereafter. The animals were euthanized on the 28(th) day at which time aortic blood was obtained to assess blood insulin and C-peptide by radioimmunoassay, and pancreatic tissue samples were collected and used to determine the expression of the glucose transporter-2 (GLUT2) by real-time polymerase chain reaction (RT-PCR) and Western Blot.

RESULTS

Fasting blood glucose in the clozapine group was significantly higher at the 14(th), 21(st), and 28(th) day compared to baseline, but rats receiving clozapine and metformin only had significantly elevated levels on the 14(th) day of treatment. However, repeated measures ANOVA found no statistically significant differences in blood glucose levels over time between the three groups (p=0.136). Multiple comparison tests found that the mean insulin level in the clozapine+metformin group was significantly lower than the levels in the clozapine and saline groups. There were statistically significant differences in the expression of GLUT2 mRNA (clozapine+metformin group < clozapine group < saline group) and in the expression of GLUT2 protein (clozapine+metformin group, clozapine group < saline group).

CONCLUSION

This study found a non-significant increase in fasting blood glucose in SD rats treated with clozapine that was partially counteracted by concurrent administration of metformin. Rats administered clozapine showed the expected decrease in the expression of GLUT2, but concurrent administration of metformin and clozapine for 28 days did not show the expected normalization of the expression levels of GLUT2.