Effects of dietary lipids on hepatic protein synthesis and lipid metabolism in the rat

Publisher Website
Google Scholar
Abstract
The effects of dietary cholesterol, cholic acid, or high fat on hepatic protein synthesis were studied in rats. The feeding of 1.5% cholesterol or 20% corn oil in the diet caused significant inhibition of leucine-C14 incorporation into protein in vitro; the effect of 0.5% cholic acid was less striking. The feeding of a diet containing all three factors (cholesterol, cholic acid, and high fat) resulted in the greatest inhibition of hepatic protein synthesis in vitro. This dietary effect was confirmed in vivo when methionine-S35 incorporation into liver proteins was measured in male and female rats. Comparison between the control purified diet and laboratory chow showed no differences. Appropriate experiments in vitro employing 105,000-g cell sap fractions and microsomes ruled out any apparent effect of diet on the activation and transfer of leucine-C14 to the microsomal templates. Furthermore, no effect was noted in leucine-C14 incorporation into soluble RNA in vitro. It appears that the changes in protein synthesis are consistently associated with a "defect" in the microsomal fraction.