Cholesterol-lowering in hamsters fed rice bran at various levels, defatted rice bran and rice bran oil.

This study was conducted to determine the relative cholesterol-lowering effects of several levels of full-fat rice bran in hamsters. In addition, the separate effects of defatted rice bran and/or crude rice bran oil were investigated at levels equivalent to those present in 43.7% full-fat rice bran. Diets containing 10.9, 21.8, 32.8 or 43.7% full-fat rice bran, 35% defatted rice bran and/or 9% rice bran oil were fed to 4-wk-old male hamsters. All diets contained 10% total dietary fiber, 9% fat and 3.2% nitrogen; hypercholesterolemic diets contained 0.3% cholesterol; two diets were cholesterol-free, i.e., 10% cellulose and 43.7% full-fat rice bran. After 21 d, plasma and liver cholesterol, plasma triglycerides and liver weights were significantly greater in hamsters fed the 10% cellulose diet with 0.3% cholesterol compared with those fed the cholesterol-free cellulose diet. In animals fed cholesterol-free diets, plasma cholesterol values were significantly lower in those fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. In animals fed cholesterol-containing diets, plasma and liver cholesterol were significantly lower in animals fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. Plasma cholesterol reductions were significantly correlated to the level of rice bran in the diet. In cholesterol-fed hamsters, total liver cholesterol content was significantly lower in those fed the defatted rice bran diet with rice bran oil compared with those fed the cellulose diet. Full-fat rice bran was the only treatment that significantly lowered both plasma and liver cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of vitamins A and E in blood and liver of rats depleted of vitamin A or vitamin E.

Young Sprague-Dawley male rats (n = 150) were fed a semipurified diet, either without vitamin A (VA), without vitamin E (VE) or supplemented with both vitamins A and E (control). At the end of weeks 0, 1, 3, 5, 6, 7, 8 and 9, groups of rats were anesthetized with methoxyflurane, and blood was collected by cardiac puncture until the rat was exsanguinated. The liver was excised. Whole blood (WB) from each rat was fractionated into plasma (PLA), leukocytes (LEU), platelets (PLT) and erythrocytes (RBC). Each blood component was extracted with heptane and livers were extracted with CHCl3/CH3OH (2:1, v/v). The extracts were analyzed for VA and VE by high performance liquid chromatography. The relationship among blood components in the loss of VA was PLT = LEU greater than WB greater than PLA. The relationship among blood components in the loss of VE was PLA greater than RBC greater than WB greater than LEU = PLT. VA and VE levels in other blood components decreased precipitously between weeks 0 and 4 in the animals placed on deficient diets. These results and correlation analyses between vitamin contents of blood components and of livers indicate inadequacies for the use of certain blood components as monitors of lipid-soluble vitamin status in the rat.

Bioavailability of vitamin E in rats fed graded levels of pectin.

Dietary pectin at levels of 0, 3, 6 and 8% was fed ad libitum to rats for 8 wk to evaluate whether the bioavailability of vitamin E fed at 0.001% of the diet was affected by pectin. Rats fed 3% pectin were not different in any vitamin E parameters from those fed 0% pectin. By the end of the study body weights were significantly lower in the 6 and 8% pectin groups after adjusting for their nonsignificant trend of lower food intake. At wk 8, liver vitamin E levels were reduced in the 6 and 8% pectin group compared to values at the start of the study. Both groups had significantly higher red blood cell hemolysis compared to 0% pectin at 8 wk. Fecal fat excretion was not different among the diet groups, but weights of the small and large intestines were significantly increased in rats fed 6 or 8% pectin compared to those fed 0 or 3%. Our results show that 6 and 8 but not 3% dietary pectin decreased vitamin E availability in rats.

Comparative pharmacokinetics of vitamin A (retinol) in rats and hamsters.

The absorption and elimination of all-trans-retinol in the plasma of rats and hamsters were studied after an oral dose of 45 mg/kg body weight. The hamsters exhibited a higher pretreatment mean circulating retinol concentration than rats maintained on an identical diet. The increase in plasma retinol after a single oral dose was much greater in hamsters than rats. The area under the plasma concentration v. time curve was approximately 60% greater for rats than for hamsters. The elimination half-times for rats were much longer than for hamsters. Plasma retinol uptake and disappearance were consistent with a two-compartment open model with first-order absorption.

Use of antioxidants in the analysis of vitamins A and E in mammalian plasma by high performance liquid chromatography.

A simple, sensitive, quantitative method for the simultaneous assay of retinol, alpha-tocopherol and gamma-tocopherol in rat, guinea pig, monkey and human plasma was developed by using high performance liquid chromatography. It was found that antioxidant was required to stabilize the fat-soluble vitamins in the plasma of rats. The effect of several antioxidants on the recovery of fat-soluble vitamins was evaluated. Results showed that 0.125% butylated hydroxytoluene (BHT) in ethanol and 0.025% BHT in heptane yielded recoveries greater than 95% in 0.1 ml plasma.

Use of antioxidants in the analysis of vatamins A and E in mammalian plasma by high performance liquid chromatography.

A simple, sensitive, quantitative method for the simultaneous assay of retinol, α-tocopherol and γ-tocopherol in rat, guinea pig, monkey and human plasma was developed by using high performance liquid chromatography. It was found that antioxidant was required to stabilize the fat-soluble vitamins in the plasma of rats. The effect of several antioxidants on the recovery of fat-soluble vitamins was evaluated. Results showed that 0.125% butylated hydroxytoluene (BHT) in ethanol and 0.025% BHT in heptane yielded recoveries >95% in 0.1 ml plasma.