Zinc and ethanol: Dietary interrelationships in pregnant rats

Abstract

Pregnant rats were fed three different liquid diets with ethanol providing 33.3, 35.6 and 50.8% of the total calories. The 35.6 and 50.8% ethanol diets, containing egg white as a source of protein, were zinc deficient and were fed to two groups of rats without zinc supplementation. At each level of ethanol, one additional group was supplemented with a moderate level of zinc and another group with a high level of zinc. The 33.3% ethanol diet contained casein as a source of protein and had a high level of zinc. Each rat in the ethanol group was yoked with another rat fed a diet in which the ethanol was replaced by an isocaloric amount of carbohydrate. Records were kept of food consumed, weight gained or lost, number of pups delivered, total weight of litter, and weights of each pup. Maternal and neonatal tissues were taken for zinc and copper analyses. The rats fed ethanol diets were found to ingest the same amount of ethanol-derived calories per day regardless of diet or concentration of ethanol. On the higher level of ethanol (50.8%), the rats, therefore, ingested fewer total calories and lost weight. No pups were delivered from this group of dams. Their respective pair-fed groups, although restricted in weight gain, delivered live pups at all levels of zinc. The pups from dams fed zinc-deficient diets had lower total body zinc levels and lower liver zinc levels. Sufficient dietary zinc improved the condition of the pregnant rats and their progeny, but there were no indications that higher levels of dietary zinc resulted in further improvement. Zinc content of tissues from adult rats, 130 days old, produced from dams fed the 35.6% ethanol-derived calories with egg white protein diet was not essentially different from similar tissues of adult animals produced by control pair-fed dams. Copper levels in the liver were higher in dams on high ethanol diets than in the livers of their pair-fed controls. Although the whole body zinc levels of newborn pups were lower than those from their pair-fed controls, the magnesium levels of the same pups were higher. The whole body copper levels were the same for both groups. Newborn rats from dams fed sufficient zinc had higher levels of zinc in the skin, liver, and kidney but lower levels in bone than those of their corresponding dams.