silicon and Obesity

The prevalence of metabolic syndrome components, such as obesity, glucose intolerance and hepatic steatosis, is rapidly increasing and becoming a major issue of public health. The present work was designed to determine the effects of Spirulina platensis (Sp) algae and silicon-enriched Sp on major metabolic syndrome components in obesogenic diet-fed rats. Forty male Wistar rats were divided into 4 groups. Ten rats were fed a control diet and 30 rats were fed a high fat (HF) diet. The HF groups were divided into three groups and supplemented with placebo or Sp or Si-enriched Sp for 12 weeks. Dietary intake and body weight were recorded. Oral glucose tolerance test and surrogate metabolic syndrome (insulin, leptin, adiponectin and lipids), mitochondrial function (enzymatic activity of respiratory chain complexes and β-hydroxyacyl-CoA dehydrogenase), NADPH oxidase activity and several long-established oxidative stress markers were measured in the blood and liver. The HF diet induced obesity, glucose intolerance, hepatic steatosis and huge metabolic alterations, associated with higher NADPH oxidase activity and lower hepatic sulfhydryl group and glutathione contents. Otherwise, the Sp and Sp + Si supplements showed some interesting effects on rat characteristics and particularly on blood and hepatic metabolic parameters. Indeed, the intake of Sp or Sp + Si mainly improved glucose tolerance and decreased the enzymatic activity of hepatic NADPH oxidase. Overall, Si supplementation of spirulina does not appear to have more beneficial effects than spirulina alone. Other experiments with different species of rats/mice, different diets or different durations of diet intake should be undertaken to confirm or invalidate these results.

Topics: Animals; Glucose; Glucose Tolerance Test; Humans; Liver; Male; NADPH Oxidases; Obesity; Rats; Rats, Wistar; Silicon; Spirulina

Insulin resistance is a major contributor to macro- and microvascular complications, particularly in the presence of the metabolic syndrome, and is also associated with polycystic ovary syndrome. Impaired nitric oxide metabolism and endothelial function are important components of the vascular disease. Increasing the bioavailability of arginine, the precursor of nitric oxide, thus potentially offers protection against end-stage disease. We have recently demonstrated that dietary supplementation with a novel silicate inositol arginine complex reduces vasculopathy and glomerular sclerosis in the insulin-resistant JCR:LA-cp rat. The objective of this study was to address the absorption of, and the underlying metabolic alterations caused by, the arginine silicate inositol complex and arginine HCl (as a reference agent) in obese insulin-resistant male and female JCR:LA-cp rats. Male and female rats were treated with the preparations at 1.0 mg/(kg d) (expressed as arginine HCl) from 8 to 12 and 12 to 18 weeks of age, respectively. Obese female, but not male, rats treated with the arginine silicate inositol complex showed a reduced rate of weight gain without concomitant reduction in food intake. Plasma silicon levels were raised very significantly in arginine silicate-treated rats, consistent with significant absorption of the complex. In male rats, arginine levels were elevated by treatment with arginine silicate only; and female rats responded to both preparations. Plasma concentrations of oxides of nitrogen in rats treated with the silicate complex showed a dimorphism, decreasing in male and increasing in female rats. Fasting insulin levels were elevated in male rats treated with the arginine silicate complex, whereas fasting and postprandial insulin levels were decreased in female rats. Furthermore, female, but not male, rats treated with either of the arginine preparations showed significant reductions in cholesterol, triglyceride, and phospholipid concentrations. We conclude that the arginine silicate inositol complex is absorbed efficiently, raising plasma arginine levels, and is more biologically effective than the free amino acid hydrochloride. This has different beneficial metabolic effects in both sexes of an animal model of insulin resistance and cardiovascular disease, consistent with reduction in end-stage disease.

Topics: Animals; Arginine; Blood Glucose; Body Weight; Eating; Female; Inositol; Insulin; Insulin Resistance; Lipids; Male; Nitric Oxide; Obesity; Rats; Rats, Inbred Strains; Silicates; Silicon