Effect of anti-oxidants, Ricetrienol and α-tocopherol, on adipocytokine abnormalities and fatty liver in Otsuka Long-Evans Tokushima Fatty diabetic rats.

INTRODUCTION: We investigated the effect of Ricetrienol, which is an anti-oxidant extracted from rice bran, and α-tocopherol on the adipocytokine abnormalities and fatty liver in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. MATERIALS AND METHODS: A total of 18 OLETF rats were bred using a 30% sucrose solution (the diabetic group; DM), whereas another 18 OLETF rats were bred using ordinary water (the non-diabetic obese group; OB) as drinking water, respectively. After the sucrose-fed rats developed diabetes, all of the rats from the diabetic and obese groups were randomly divided into three groups. Then each group was fed either standard chow (DM-S, OB-S group), 0.05% Ricetrienol-containing chow (DM-R, OB-R group) or 0.05%α-tocopherol-containing chow (DM-A, OB-A group), respectively. After 12 weeks of feeding, all the rats were killed. Plasma insulin, adiponectin, resistin and leptin were assayed by enzyme immunoassay. Histopathological findings of liver tissue were scored according to Brunt and Kleiner's method, and triglyceride contents of the liver tissue were investigated. RESULTS: Plasma adiponectin was significantly reduced in DM-S compared with OB-S, but it had significantly increased in DM-R and DM-A as opposed to DM-S. Plasma resistin showed a significant increase in DM-S compared with OB-S, but it was significantly reduced in DM-A than in DM-S. Though the triglyceride contents of liver tissue significantly increased in DM-S as opposed to OB-S, they were significantly reduced in DM-R compared with DM-S. Histopathological scores were significantly higher in DM-S than OB-S. CONCLUSIONS: The present study shows that Ricetrienol might prevent adipocytokine abnormalities and fatty liver in OLETF diabetic rats. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00090.x, 2011).

Production and characterization of functional substances from a by-product of rice bran oil and protein production by a compressed hot water treatment.

A by-product of rice bran oil and protein production was treated with water and compressed hot water at 20 degrees C to 260 degrees C for 5 min, and at 200 degrees C and 260 degrees C for 5 to 120 min. Each extract was evaluated for its yield, radical scavenging activity, carbohydrate, protein, total phenolic and furfural contents, molecular-mass distribution and antioxidative activity. The maximum yield was obtained at 200 degrees C. The radical scavenging activity and the protein, total phenolic and furfural contents of the extract increased with increasing temperature. However, the carbohydrate content abruptly decreased when treated at above 200 degrees C. The extract treated at 260 degrees C for 5 min exhibited suppressive activity toward the autoxidation of linoleic acid. Each extract obtained at temperatures lower than or equal to 200 degrees C exhibited emulsifying ability.

Rice bran extract prevents the elevation of plasma peroxylipid in KKAy diabetic mice.

Oxidative stress is now considered to be a key factor in the development of diabetes and its complications. In this study, we examined the anti-oxidative effects of a crude lipophilic rice bran extract, Ricetrienol, which contains alpha-tocopherol, tocotrienol and phytosterol, in obese diabetic KKAy mice. We used KKAy mice fed a normal diet (DM group) or a diet including 0.1% Ricetrienol (RT group), and non-diabetic C57BL mice (C group). After 6 weeks, body weight, HbA1c, plasma glucose, lipids, peroxylipid (malonedialdehyde, MDA), alpha-tocopherol and glutathione peroxidase 1 (GPx) mRNA expression in the kidney were measured. At 1 week and at the end of the experimental period, urine 8-isoprostane and 8-hydroxy deoxyguanosine (8-OHdG) were also measured. Ricetrienol administration did not affect hyperglycemia, body weight or hyperlipidemia. Plasma MDA, urine 8-isoprostane and 8-OHdG in the DM group were significantly increased compared with the C group and the elevation of plasma MDA was significantly suppressed by 0.1% Ricetrienol. GPx mRNA expression was significantly increased in the RT group when compared with the C group. Plasma alpha-tocopherol in the RT group was significantly higher than that in the DM group. These findings suggest that Ricetrienol exerts a protective effect against oxidative damage in diabetes mellitus.

Increased production of bioactive lysophosphatidic acid by serum lysophospholipase D in human pregnancy.

Lysophosphatidic acid (LPA) is a prototype of the lysophospholipid mediator family and has multiple effects in the female reproductive system. Although several metabolic routes have been reported for intracellular formation of LPA, a unique route involving lysophospholipase D, an extracellular enzyme that produces LPA in blood and body fluids, is particularly intriguing for its agonistic role. In this study, using an assay with radioactive palmitoyl-lysophosphatidylcholine, we found that lysophospholipase D activity producing palmitoyl-LPA in human serum gradually increased during pregnancy. Elevated activity of lysophospholipase D was not caused by changes in levels of their precursors, lysophosphatidylcholines, in nonpregnant women or in pregnant women at different gestational periods. With increasing length of gestation, the elevated activity in pregnant women was found to produce increasing proportions of LPA with a palmitoyl group versus other LPAs. These results suggest that LPA formed by increased activity of lysophospholipase D in blood might participate in maintenance of pregnancy.

Increased formation of lysophosphatidic acids by lysophospholipase D in serum of hypercholesterolemic rabbits.

Lysophosphatidic acid (LPA) is a biologically active phospholipid that has been identified as a vasoactive principle in incubated plasma and serum of mammals. Previously, we found that mammalian plasma and serum contain a lysophospholipase D, which hydrolyzes lysophosphatidylcholines (LPCs) with different fatty acyl groups to the corresponding LPAs during its incubation at 37 degree C. In this study, we examined whether lysophospholipase D activity and levels of LPCs in rabbit serum were modulated by feeding rabbits a high cholesterol diet. Results showed that the serum levels of LPCs increased gradually in animals fed a high cholesterol diet for 12 weeks. We found that the levels of individual LPAs formed on incubation of serum for 24 h increased with an increase in the period of feeding of rabbits a high cholesterol diet. LPA with a linoleate residue was the most abundant LPA, followed in order by 16:0-, 18:1- and 18:0-LPAs. LPA was found to increase attachment of the monocytic cell line THP-1 to vascular endothelial cells pre-stimulated with tumor necrosis factor-alpha. These results indicated that increases in the levels of LPAs generated by lysophospholipase D in the blood of hypercholesterolemic rabbits may be relevant to attachment of monocytes to vascular walls, a key phenomenon observed at an early stage of atherosclerosis.