This study was designed to determine whether incorporation of gamma-tocotrienol or alpha-tocopherol in an atherogenic diet would reduce the concentration of plasma cholesterol, triglycerides and fatty acid peroxides, and attenuate platelet aggregability in rats. For six weeks, male Wistar rats (n = 90) were fed AIN76A semisynthetic test diets containing cholesterol (2% by weight), providing fat as partially hydrogenated soybean oil (20% by weight), menhaden oil (20%) or corn oil (2%). Feeding the ration with menhaden oil resulted in the highest concentrations of plasma cholesterol, low and very low density lipoprotein cholesterol, triglycerides, thiobarbituric acid reactive substances and fatty acid hydroperoxides. Consumption of the ration containing gamma-tocotrienol (50 mg/kg) and alpha-tocopherol (500 mg/kg) for six weeks led to decreased plasma lipid concentrations. Plasma cholesterol, low and very low density lipoprotein cholesterol, and triglycerides each decreased significantly (P < 0.001). Plasma thiobarbituric acid reactive substances decreased significantly (P < 0.01), as did the fatty acid hydroperoxides (P < 0.05), when the diet contained both chromanols. Supplementation with gamma-tocotrienol resulted in similar, though quantitatively smaller, decrements in these plasma values. Plasma alpha-tocopherol concentrations were lowest in rats fed menhaden oil without either chromanol. Though plasma alpha-tocopherol did not rise with gamma-tocotrienol supplementation at 50 mg/kg, gamma-tocotrienol at 100 mg/kg of ration spared plasma alpha-tocopherol, which rose from 0.60 +/- 0.2 to 1.34 +/- 0.4 mg/dL (P < 0.05). The highest concentration of alpha-tocopherol was measured in plasma of animals fed a ration supplemented with alpha-tocopherol at 500 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)
Although both adrenalectomized and intact Long Evans rats absorbed the same amount of fat over a 24 hr period, the livers of the intact rats accumulated triglyceride while the livers of the adrenalectomized rats failed to do so. Of the glycerides excreted in the feces, the adrenalectomized rat excreted a significantly higher proportion of triglycerides while the intact rats excreted primarily monoglycerides. Fecal excretion of bile acids and phospholipids was significantly lower in the adrenalectomized rats compared to intact rats. Thus adrenal hormones appear to influence intestinal lipolysis. Serum and liver phospholipids appeared to be significantly lower in response to a fat load in adrenalectomized rats compared to intact rats. The phospholipid content of the small intestinal wall was five‐fold higher in the intact rats than in the adrenalectomized rats. The adrenal gland appears to control phospholipid synthesis during triglyceride assimilation.
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