Modification of in vitro rat adrenal corticosteroidogenesis by dietary fat

Three groups of male weanling Holtzman rats were maintained, ad libitum, for 4 and 8 weeks on 1 of 3 diets: Purina Chow, hydrogenated soybean fat, and milk fat diets. The fats were added at the level of 36% total calories in the case of the hydrogenated soybean and milk fat diets. Adrenal homogenates prepared from tissues of each group of animals at the end of the dietary periods were used to measure the relative abilities to synthesize corticosteroids from endogenous substrates. Endogenous free cholesterol levels were found adequate to sustain the level of corticosteroids obtained. No concomitant cholesteryl ester hydrolysis was observed under the experimental conditions used. The adrenal synthetic ability for the three dietary groups was in the order milk fat > Purina Chow > hydrogenated milk fat. This order appeared not to be a reflection of the essential fatty acid status of the animals in the three dietary groups. The possible basis for this trend, and the implications of the findings for carbohydrate, protein, and lipid metabolism in the animal are indicated. Presented in part at the AOCS Meeting, New Orleans, April 1973.