Short-Term Effect of Zinc Sulphate on Plasma and Hepatic Concentrations of Vitamins A and E in Normal Weanling Rats

Abstract

In normal weanling male rats, the intraperitoneal administration of zinc sulphate (ZnSO₄) resulted in a decreased hepatic and an increased plasma concentration of vitamin A after 2 h. In an in vitro study, the vitamin A concentrations of liver homogenates were markedly increased when homogenized livers were treated with ZnSO₄. ZnSO₄, however, did not show any effect on plasma and liver concentrations of vitamin E. These results indicate that zinc may be specifically involved in mobilizing vitamin A from liver to the circulation of normal animals within a short period. The trace element, therefore, could be used not only to treat cases of depressed vitamin A in plasma but also to treat hepatic toxicity from hypervitaminosis A.

Effect of Insulin Treatment or Zinc Supplementation on Vitamin A Status in Streptozotocin-Induced Diabetic Rats.

“…The decreased plasma concentrations of retinol have been suggested to be due to a deficiency of zinc, which metal ion is required for the synthesis of the RBP, the protein that binds retinol in the liver for secretion into the plasma [11]. Thus, in situations such as in alcoholic cirrhosis, where reduced plasma vitamin A is accompanied by a poor zinc status, vitamin A supplementation alone did not improve the abnormal dark adaptation suffered by the patients [10].…”

“…The retinol carrier proteins, such as RBP and transthyretin (TTR), have been found to be decreased in the plasma and liver, as well as in the kidney, of STZ-induced diabetic rats [9], suggesting an impaired mobilization of vitamin A from its hepatic storage to the circulation. Zinc is required for the synthesis of RBP [10,11] and has been shown to promote the transport of vitamin A from the liver [12,13]. Since zinc metabolism is known to be perturbed in the presence of diabetes [14][15][16][17], it is possible that supplementation with this trace element may enhance the hepatic synthesis of RBP and thereby reverse the decreased plasma retinol found in diabetes.…”

Vitamin A, zinc and lung cancer

“…Conversely, large doses of zinc to rats raise serum vitamin A levels, and deplete liver stores of vitamin A (Ette et al, 1979). These results suggest that zinc may be involved in the synthesis of RBP.…”

Retinol binding protein expression is induced in HepG2 cells by zinc deficiency

“…Zn repletion of deficient cell cultures has been observed to restore Zn deficiency‐induced elevations in p53 mRNA to normal levels [6] and to inhibit the apoptotic effects of Zn depletion [29,31]. In animal studies, restoration of liver and plasma vitamin A levels resulting from Zn deficiency occurred after a time‐lag of several days following either dietary supplementation or a single, bolus injection of ZnSO 4 [32,33]. In humans, plasma retinol levels were observed to be increased at 6 months following Zn supplementation [11].…”