Effect of Hypophysectomy on the Metabolism of Essential Fatty Acids in Rat Testes and Liver

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Abstract
The effect of hypophysectomy on lipid classes and interconversion of linoleic acid in livers and testes of essential fatty acid (EFA)-deficient rats is described. Male rats of the Sprague Dawley strain made EFA-deficient by feeding them a fat-free diet from weaning to 26 weeks of age were used. Hypophysectomy caused a marked elevation of the percentage of cholesteryl esters, glyceryl ether diesters and triglycerides at the expense mainly of phosphatidylcholine and phosphatidylethanolamine in the testes. There was a small effect of hypophysectomy on the composition of the liver lipids with only a slight increase in the percentage of polar lipids and corresponding slight decrease in the percentage of the neutral lipid fraction 3 weeks after the operation. The characteristic pattern of fatty acid interconversions, on feeding linoleate, occurred in both livers and testes of hypophysectomized (hypox) animals. However, the conversion of linoleic acid to higher polyunsaturated fatty acids was not as efficient in the testes of hypox as normal animals. Despite the marked change in fatty acid composition produced from feeding linoleate there appeared to be little effect on the pattern of changes in lipid class composition caused by hypophysectomy. The results suggest that the hypophyseal hormones exercise control over the transformation of fatty acids among the lipid classes.