SELECTIVE REDUCTION OF DELTA-6 AND DELTA-5 DESATURASE ACTIVITIES BUT NOT DELTA-9 DESATURASE IN MICROPIGS CHRONICALLY FED ETHANOL

This study investigated the mechanism by which chronic ethanol feeding reduces arachidonate and other highly unsaturated fatty acids in pig liver phospholipids. Five micropigs were fed a diet providing 89 kcal/ kg body wt for 12 mo, with ethanol and fat as 40 and 34% of energy, re spectively. Five control pigs were pairfed corn starch instead of etha nol. The activities of Delta 6 and Delta 5 desaturases (expressed as m icrosomal conversion of precursor to product) in liver from ethanol-fe d pigs were reduced to less than half that of controls, whereas the ac tivity of Delta 9 desaturase was unaffected in the ethanol group. Delt a 5 Desaturase activity shelved positive correlation with the abundanc e of its products in liver total phospholipids and microsomes in the e thanol group, but not in the controls. Correlation between Delta 6 des aturase activity and its products showed similar pattern to that of De lta 5 desaturase, but did not reach statistical significance. No diffe rence was observed between the two groups in coenzyme A concentration in the liver. These results suggest that the selective reduction of De lta 6 and Delta 5 desaturase activities, not the microsomal electron t ransport system, are directly responsible for the altered profile of l iver phospholipids.