Water-soluble rice bran enzymatic extract attenuates dyslipidemia, hypertension and insulin resistance in obese Zucker rats.

BACKGROUND AND PURPOSE: Rice bran enzymatic extract (RBEE) has advantages compared to the original rice bran or its oils including water solubility, lack of rancidity and increased content in high nutritional proteins and nutraceutical compounds, particularly phytosterols, γ-oryzanol and tocols. Our aim was to determine the beneficial effects of RBEE in the pathogenesis of metabolic syndrome in obese Zucker rats. METHODS: Obese Zucker rats and their lean littermates were fed a 1 and 5 % RBEE-supplemented diet (O1, O5, L1 and L5). Simultaneously, obese and lean Zucker rats, fed a standard diet, were used as controls (OC and LC, respectively). Body weight, food and water intake, and systolic blood pressure were weekly evaluated. After treatment, biochemical assays of serum glucose, insulin, triglycerides (TG), total cholesterol (TC), non-esterified fatty acids (NEFA), adiponectin and nitrates (NO((x))) were determined. RESULTS: RBEE treatment reduced circulating levels of TG and TC, whereas increased HDL-cholesterol without altering NEFA values in obese rats. The extract also induced a significant dose-dependent reduction of hypertension linked to obesity. RBEE of 5 % improved insulin resistance and subsequently reduced HOMA-IR index without altering serum glucose levels. Obese animals treated with RBEE showed partial restoration of adiponectin levels and a significant attenuation of pro-inflammatory values of NO((x)). CONCLUSION: These findings evidence the nutraceutical properties of RBEE against the pathogenesis of metabolic syndrome by attenuating dyslipidemia, hypertension and insulin resistance as well as by restoring hypoadiponectinemia associated to obesity.

Simvastatin improves endothelial function in spontaneously hypertensive rats through a superoxide dismutase mediated antioxidant effect.

BACKGROUND: Hydroxymethylglutaryl coenzyme A (HMGCoA) reductase inhibitors have beneficial effects beyond their cholesterol-lowering properties. The antioxidant mechanism of HMGCoA reductase inhibitors is not completely understood. OBJECTIVES: To elucidate the antioxidant effect of simvastatin. METHODS: We studied the influence of simvastatin treatment on the development of hypertension, modification of antioxidant systems, and reactivity of aortic rings in Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. RESULTS: Simvastatin had no effect on blood pressure (BP). Simvastatin treatment (either 1 or 2 mg/kg body weight for 12 or 20 weeks) increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in SHR rats compared with untreated control SHR rats. Carbachol-induced relaxation of aortic rings was impaired in control SHR rats and was restored by simvastatin treatment. Addition of SOD improved the response in control SHR rats and did not have any effect in treated SHR rats. Addition of diethyldithiocarbamic acid, a selective inhibitor of SOD, produced a mild non-significant impairment in carbachol-induced relaxation in control SHR rats, suggesting a deficient antioxidant system in these animals. However, in treated SHR and in WKY rats, impairment of the relaxation was marked, implying that SOD activity in these animals was important to maintain endothelial function. In aortic rings without endothelium from SHR rats, contraction induced by free radicals was substantially higher than in WKY rats. This effect was attenuated in 1-mg-treated rats and abolished in 2-mg-treated rats. CONCLUSIONS: Simvastatin promotes intracellular antioxidant systems, fundamentally SOD, restoring endothelial function but not having any effect on blood pressure.

Effects of chronic treatment with the CB1 antagonist, rimonabant on the blood pressure, and vascular reactivity of obese Zucker rats.

Rimonabant (RM) is a cannabinoid CB1 receptor antagonist useful in the treatment of obesity associated cardiovascular risk factors. Since cannabinoids are vasoactive compounds, the aim of this study is to evaluate the effect of chronic treatment with RM on systolic blood pressure (SBP), and endothelial and vascular reactivity. Obese Zucker rats (OZRs) and their lean counterparts were orally treated during 20 weeks with either RM (10 mg/kg/day). Endothelial and vascular function was assessed in aorta and small mesenteric arteries (SMAs) by concentration response curves to acetylcholine (ACh) and phenylephrine (Phe), respectively. Participation of nitric oxide (NO) was evaluated by incubation with the NO synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME) and cyclooxygenase (COX)-derived products involvement was analyzed by incubation with indomethacin (INDO). Plasma lipid profile, insulin and adiponectin were also analyzed. Sympathetic activity was evaluated by urinary excretion of noradrenaline. As expected, RM decreased body weight gain and enhanced adiponectin concentration. Insulin resistance and sympathetic activity were also decreased. The increase in SBP observed in OZRs was reduced by treatment with RM. Aortae and SMAs from OZRs exhibited lower contractile response to Phe, being this effect prevented by RM administration. Although ACh-induced response and NO participation remained unaltered with obesity, enhanced COX-derived constrictor products were found in OZRs. RM treatment neither altered endothelium-dependent relaxation nor L-NAME-sensitive component of the response. Nevertheless, it was able to regulate COX-derived vasoactive products participation. Those effects may contribute to explain some of the cardiovascular protective actions elicited by this drug.