Lipid composition of the synaptosome and erythrocyte membranes during chronic ethanol-treatment and withdrawal in the rat.

Male Sprague-Dawley rats were intoxicated by inhalation of ethanol vapor for 21 days. This allowed high tolerance to the hypnotic effect of ethanol and withdrawal syndrome to be developed. The chronic intoxication brought about modifications of the synaptosome and erythrocyte membrane lipid composition which were not due to the reduction in food intake that parallels intoxication. The fatty acid composition of the phospholipids was modified but the level of cholesterol and the level of phospholipid remained unchanged. The modifications concerned the levels of linoleic (18:2) and arachidonic (20:4) acids which decreased in the synaptosomes. In the red blood cell membranes, ethanol affected the levels of the octadecenoic acids (18:1) which rose, and linoleic acid (18:2) which fell. These disturbances were present when the withdrawal syndrome was at its highest and also 3 days after withdrawal when the signs of hyperexcitability were no longer visible in the animal. Modifications in the brain membrane lipid composition parallel the behavioral tolerance to ethanol; however the present results show that the apparent readaptation of the central nervous system to withdrawal of alcohol occurs earlier than the return to normal of the membrane lipid modifications.