THE AMELIORATION OF HYPERVITAMINOSIS D IN RATS WITH VITAMIN A

Open Access
Publisher Website
Google Scholar
Abstract
Toxic amounts of vitamins A and D were given to rats to increase the rate of bone resorption. Contrary to expectations, large doses of vitamin A ameliorated hypervitaminosis D. Vitamins were administered daily on the basis of body weight. When 60,000 units of vitamin D were given, all rats were dead within 3 weeks. Survival time was increased almost 2 weeks by adding 15,000 units of vitamin A to the diet daily. If 30,000 units of vitamin A were added, rats survived at least 6 weeks. Despite the prolongation of life, weight loss began during the first week in all treated animals. When 18,000 units of vitamin D were administered, the rats gained weight for 3 weeks, and then some began to lose weight. Administration of graded amounts of vitamin A together with the 18,000 units of vitamin D increased the amount of weight gained, the greatest gain occurring in animals receiving the largest amount of vitamin A (30,000 units). Rats treated only with vitamin D showed extensive kidney and arterial wall calcification. Simultaneous administration of vitamin A markedly decreased calcification, and in some cases prevented it entirely. Calvaria and long bones of hypervitaminotic D animals showed evidence of advanced bone resorption. This resorption was prevented almost completely in rats receiving supplemental vitamin A. In summary, the administration of relatively large amounts of vitamin A to hypervitaminotic D rats decreases the toxicity of this condition as evidenced by increased longevity, better weight gain, decreased soft tissue calcification and by considerable improvement in the histologic appearance of osseous structures.