Depletion of liver and esophageal epithelium vitamin a after chronic moderate ethanol consumption in rats: Inverse relation to zinc nutriture

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Abstract
This study was designed to determine whether chronic moderate ethanol ingestion alters the levels of vitamin A of liver and esophageal epithelium and if this is dependent on zinc nutriture. Forty male Sprague-Dawley 4-week-old rats were divided into five groups: zinc-deficient (0.9 ppm), ethanol-fed; zinc-deficient; zinc-adequate (25 ppm); zinc-adequate (25 ppm), ethanol-fed; and zinc-supplemented (50 ppm), ethanol-fed. All rats received liquid Lieber-DeCarli diet containing 4,000 IU per liter of vitamin A for 5 weeks. Zinc-deficient, ethanol-fed rats and zinc-adequate, ethanol-fed rats and zinc-supplemented, ethanol-fed rats received 15.5% of the caloric intake as ethanol while zinc-deficient and zinc-adequate rats received isocaloric amounts of maltose dextrin. All groups were pair-fed to zinc-deficient, ethanol-fed rats. In addition, a group of eight rats designated as weight-restricted controls were fed a diet similar to the one given to zinc-adequate rats but in the amount to obtain a final weight as in the zinc-deficient group. After 35 days, the liver histology was normal in all rats, and no fat accumulation was noted. Hepatic vitamin A concentration was significantly decreased in zinc-adequate, ethanol-fed rats (41 ± 10 μg per gm) and further in zinc-supplemented, ethanol-fed rats (12 ± 5 μg per gm) as compared to controls (137 ± 49). A highly significant negative correlation between serum zinc and liver vitamin A was found in ethanol-fed animals. In zinc-deficient, ethanol-fed rats, ethanol did not induce mobilization of liver vitamin A, however, it caused a significant reduction in the ratio of retinyl ester to retinol (53 ± 16%) as compared to controls. Zinc deficiency in the absence of alcohol caused a reduction of hepatic vitamin A concentration and total content, and this effect was not secondary to protein-caloric malnutrition as values were unaffected in weight-restricted controls. In esophageal epithelium, a significant reduction of vitamin A stores was noted in zinc-supplemented, ethanol-fed rats (0.67 ± 0.7 μg per gm) as compared to controls (3.3 ± 1.0, p < 0.01), and a significant negative correlation was seen between serum zinc and esophageal vitamin A levels of ethanol-fed rats. These results demonstrate that ethanol in moderate quantities causes profound alterations of the vitamin A status of the liver and esophagus, and these effects are inversely correlated to zinc nutriture.