Increase in hepatic content of oleic acid induced by dehydroepiandrosterone in the rat

The effects of dehydroepiandrosterone (DHEA) on the acyl composition of lipids in rat liver were studied. The content of oleic acid (18:1) in hepatic lipids was increased markedly by feeding rats a diet containing 0.5% (w/w) DHEA for 14 days. Treatment of rats with DHEA caused an increase in the activity of the terminal desaturase of the stearoyl-CoA desaturation system, without changing either the activity of NADH-cytochrome b5 reductase or the microsomal content of cytochrome b5. Among the changes observed in hepatic lipids, the increase in 18:1 content in phosphatidylcholine (PtdCho) was the most prominent; an approximately 2.5-fold increase in the proportion of 18:1 was induced at position 2, but not at position 1, by DHEA. This selective elevation of 18:1 at position 2 of PtdCho seems to be produced by the concerted actions of the induced 1-acylglycerophosphocholine (1-acyl-GPC) acyltransferase and the induced stearoyl-CoA desaturase. The content of 18:1 in serum lipids was unchanged by DHEA treatment, suggesting that secretion of lipids containing 18:1 into the circulation was not affected by DHEA. These results suggest that the elevation of hepatic content of 18:1 caused by DHEA treatment is mainly due to the induction of stearoyl-CoA desaturase.