Protective effects of rice bran hydrolysates on heart rate variability, cardiac oxidative stress, and cardiac remodeling in high fat and high fructose diet-fed rats

Objective: To examine the ameliorative effect of rice bran hydrolysates (RBH) on metabolic disorders, cardiac oxidative stress, heart rate variability (HRV), and cardiac structural changes in high fat and high fructose (HFHF)-fed rats.Methods: Male Sprague-Dawley rats were daily fed either standard chow diet with tap water or an HFHF diet with 10％ fructose in drinking water over 16 weeks. RBH (500 and 1000 mg/kg/day) was orally administered to the HFHF-diet-fed rats during the last 6 weeks of the study period. At the end of the treatment, metabolic parameters, oxidative stress, HRV, and cardiac structural changes were examined. Results: RBH administration significantly ameliorated metabolic disorders by improving lipid profiles, insulin sensitivity, and hemodynamic parameters. Moreover, RBH restored HRV, as evidenced by decreasing the ratio of low-frequency to high-frequency power of HRV, a marker of autonomic imbalance. Cardiac oxidative stress was also mitigated after RBH supplementation by decreasing cardiac malondialdehyde and protein carbonyl, upregulating eNOS expression, and increasing catalase activity in the heart. Furthermore, RBH mitigated cardiac structural changes by reducing cardiac hypertrophy and myocardial fibrosis in HFHF-diet-fed rats. Conclusions: The present findings suggest that consumption of RBH may exert cardioprotective effects against autonomic imbalances, cardiac oxidative stress, and structural changes in metabolic syndrome.

Sang-Yod rice bran hydrolysates alleviate hypertension, endothelial dysfunction, vascular remodeling, and oxidative stress in nitric oxide deficient hypertensive rats

Objective: To evaluate the potential therapeutic effect of Sang-Yod rice bran hydrolysates (SRH) and in combination with lisinopril against hypertension, endothelial dysfunction, vascular remodeling, and oxidative stress in rats with nitric oxide deficiency-induced hypertension. Methods: Hypertension was induced in male Sprague-Dawley rats by administration of a nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) in drinking water for 6 weeks. Hypertensive rats were administered daily with SRH (500 mg/kg/day), lisinopril (1 mg/kg/day), or the combination of SRH and lisinopril by gastric lavage for the last 3 weeks of L-NAME treatment. Hemodynamic status, vascular reactivity to vasoactive agents, and vascular remodeling were assessed. Blood and aortic tissues were collected for measurements of oxidative stress markers, plasma angiotensin-converting enzyme (ACE) activity, plasma angiotensinⅡ, and protein expression. Results: L-NAME induced remarkable hypertension and severe oxidative stress, and altered contents of smooth muscle cells, elastin, and collagen of the aortic wall. SRH or lisinopril alone reduced blood pressure, restored endothelial function, decreased plasma ACEs and angiotensinⅡlevels, alleviated oxidant markers and glutathione redox status, and restored the vascular structure. The effects were associated with increased expression of endothelial nitric oxide synthase and decreased expression of gp91phox and AT1R expression. The combination of SRH and lisinopril was more effective than monotherapy. Conclusions: SRH alone or in combination with lisinopril exert an antihypertensive effect and improve endothelial function and vascular remodeling through reducing oxidative stress and suppressing elevated renin-angiotensin system.

Rice bran hydrolysates induce immunomodulatory effects by suppression of chemotaxis, and modulation of cytokine release and cell-mediated cytotoxicity

Objective: To evaluate the immunomodulatory effects of rice bran hydrolysates on cultured immune cells and their underlying mechanism. Methods: Rice bran hydrolysates were prepared from pigmented rice (Oryza sativa L.) by hydrothermolysis and protease digestion. Rice bran hydrolysates were assayed for phenolic content and antioxidant activity. Cell proliferation of Jurkat, THP-1 and peripheral blood mononuclear cells (PBMC) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Chemotaxis was evaluated by transwell chamber methods. Immunoadherence of THP-1 was performed on cultured human umbilical vein endothelial cells (HUVEC). Cytokine released from PBMC was measured by ELISA assay kits. Lymphocyte-mediated cytotoxicity was carried out on KKU-452 cells. Proteins associated with immunomodulation were analyzed by Western immunoblotting assay. Results: Rice bran hydrolysates were rich in phenolic compounds, such as ferulic acid, catechin, quercetin, and quercetin glycosides. Rice bran hydrolysates suppressed phytohemagglutinin (PHA)-stimulated proliferation of PBMC and Jurkat cells, chemotaxis of Jurkat and THP-1 cells, and immunoadherence of THP-1 on HUVEC cultured cells. The cellular mechanism of rice bran hydrolysates involved the activation of AMPK as well as suppression of mTOR, NF-κB and VCAM-1. Rice bran hydrolysates potentiated PBMC on the PHA-stimulated release of IL-2, TNF-α, and IL-4, and enhanced PHA-induced non-MHC-restricted cytotoxicity on KKU-452 cancer cells. Conclusions: The immunomodulatory effect of phytochemicals derived from rice bran hydrolysates suggests its therapeutic potential for further investigation.