VITAMIN A AT PHARMACOLOGIC DOSES AMELIORATES THE MEMBRANE LIPID PEROXIDATION INJURY AND TESTICULAR ATROPHY THAT OCCURS WITH CHRONIC ALCOHOL FEEDING IN RATS

Abstract

The interaction of ethanol (ETOH) with testicular subcellular membranes contributes, at least in part, to alcohol-induced gonadal dysfunction. Vitamin A reaches the testes via the circulation as the retinyl ester and is converted to the free alcohol (retinol) and then to the aldehyde (retinal); retinal is the form of the vitamin which is essential for normal spermato-genesis. Because retinol can function as a free radical scavenger, testicular mitochondria were evaluated for evidence of a protective role provided by supplemental dietary vitamin A on ETOH-induced alterations in testicular structure and function in rats. Lipid peroxidation was evaluated by measurement of malonaldehyde formation and glutathione content of the testes. Compared to isocalorically matched dextrimaltose-fed controls (ISO) receiving a modified vitamin A containing diet, rats fed the corresponding ETOH diet for 50 days had a reduced testes/body ratio (ETOH: 0.0114 +/- 0.0004 vs ISO: 0.0128 +/- 0.0004). Mitochondrial enriched extracts obtained from the testes of these ETOH-fed rats showed significant increases in malonaldehyde formation; moreover, glutathione levels were reduced in the testes of the alcohol-fed animals when compared to their isocaloric controls. In contrast, no evidence for testicular atrophy was present in ETOH-fed rats receiving a standard vitamin A enriched diet; moreover, such ETOH-fed rats had a reduced rate of malonaldehyde formation as compared to their respective controls. Similarly, glutathione levels were not depleted in the testes of the ETOH-fed rats receiving the vitamin A enriched diet. Taken together, these data suggest that lipid peroxidation is a consequence of ethanol metabolism which can be attenuated, at least in part, by vitamin A.