Effect of ethanol administration on fatty acid desaturation

Abstract

The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition. Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic composition of microsomes. The delta 6 and delta 5 desaturases were inhibited by ethanol whereas the delta 9 desaturase and fatty acid synthetase were apparently modified only by diet composition. NADH-cytochrome (cyt.) c reductase was partially inhibited, whereas NADH-cyt. b5 reductase remained practically unaltered and NADPH-cyt. c reductase activity was enhanced. Decreased electrons supplied by the microsomal cyt. b5 electron transport chain would not be the reason for the inhibition of delta 6 and delta 5 desaturases by ethanol.

Selective reduction of delta 6 and delta 5 desaturase activities but not delta 9 desaturase in micropigs chronically fed ethanol.

“…These results provide new information on possible mechanisms for both the ethanol effects on essential fatty acid metabolism and its effect on hepatic function. The activity of A6 desaturase per milligram of microsomal protein in the control micropigs (Table I) was about one-tenth that of the activity in rats ( 13,14). The activity of A5 desaturase in the pigs was much higher than that of A6 desaturase (Table I), and it was fairly close to the value for rats ( 13,14).…”

“…The activity of A6 desaturase per milligram of microsomal protein in the control micropigs (Table I) was about one-tenth that of the activity in rats ( 13,14). The activity of A5 desaturase in the pigs was much higher than that of A6 desaturase (Table I), and it was fairly close to the value for rats ( 13,14). It is unknown at present whether this difference in A6 desaturase activity between the two species has any effect on tissue essential fatty acid profiles.…”

“…In rat studies, a uniform decrease in all three desaturases (A6, AS, and A9) has been reported with ethanol feeding ( 13,14). This could be due to suppression of the microsomal electron transport system or CoA ligase by ethanol, as they are common components for all three desaturases.…”

“…This could be due to suppression of the microsomal electron transport system or CoA ligase by ethanol, as they are common components for all three desaturases. On the other hand, reports of the effect of ethanol on the microsomal electron transport system have been contradictory ( 13,15,16). Another study with rats reported no ethanol effect on A6 desaturase activity (17), although this study may have been confounded by essential fatty acid deficiency.…”

The metabolism and availability of essential fatty acids in animal and human tissues

“…On the contrary, in vivo, cholesterol incorporated into diet decreased the 4 6-and A5-desaturase activity by a mechanism yet to be elucidated (Leikin and Brenner, 1987;Garg et al, 1988a,b (Narce et al, 1988 (Brenner, 1989). Ingested ethanol was also observed to decrease A6-and A5-desaturase activities (Nervi et al, 1980;Wang and Reitz, 1983 (Cunnane and Wahle, 1981) while it had no effect on A6 desaturation in liver and decreased the rate of A5 desaturation (Cunnane, 1988). High sodium chloride intake influences A6-and A5-desaturation rate in rat liver microsomes.…”