Effects of ethanol on fatty acid composition of muscle phospholipids of rats fed nutritionally complete liquid diets

Although the effects of ethanol on phospholipid fatty acid composition have been examined in single cell organisms and in rodents given ethanol as a vapor or in solution as sole drinking fluid, there are no reports of analogous experiments with nutritionally adequate liquid diets as the source of ethanol. In this experiment, young, 88 ± 5 g, male Sprague-Dawley rats given a nutritionally adequate liquid diet containing ethanol voluntarily consumed 12–18 g ethanol per kg body weight per day after 23 days. In 27 days with food intakes 64% of control, weight gains of ethanol-fed animals (group 2) were 50% of ad lib.-fed control animals (group 1) but 88% of isoenergetically pair-fed animals (group 3). Thus, energy in the ethanol diet was utilized for growth 88% as efficiently as isoenergetic diets containing dextrin. Liver and gastrocnemius muscle weights of group 2 were significantly lower than group 3 but brain weights were not similarly affected. Blood ethanol levels determined on days 14 and 24 were above 200 mg/dl at 10:00 p.m. and 7:00 a.m. but decreased to 50 mg/dl at 4:00 p.m. on a feeding schedule that began at 5:00 p.m. Dependence was confirmed by withdrawal symptomology. Compared to group 1, phospholipids isolated from gastrocnemius muscles of group 2 exhibited significant modifications in fatty acid composition. In ethanol-fed animals, 18:0 and 20:4 were lower, and 18:1 and 18:2 were higher, than ad lib.-fed controls. However, when group 2 was compared to group 3, the pair-fed control, there was no significant difference in fatty acid composition. The observed changes in fatty acid composition appear to have been due to the reduced food consumption that accompanied the model rather than to ethanol per se. These findings underline the importance of appropriate controls in liquid diet animal models of alcoholism.