Induction of rapid, synchronous vitamin A deficiency in the rat

Abstract

A procedure enabling the induction of rapid synchronous vitamin A deficiency is described. Young weanling rats were fed a vitamin A free diet until early weight plateau and were then fed, cyclically, a diet first supplemented with and then lacking in retinoic acid. Rapid, synchronized phases of vitamin A deficiency were thereby induced, in which secondary nutritional differences between animals were minimized. The effects of different levels of retinoic acid supplementation and of variations in length of the supplementation and withdrawal phases on overall growth rate, mortality, and weight loss following the withdrawal of retinoic acid were then investigated. In addition, the effect of cyclical retinoate supplementation on female mating and reproductive capacities was determined. It was found that an 18 day supplementation : 10 day deprivation cycle is optimal when animals are supplemented with 2 μg retinoic acid/gram diet, and that cycling leads to a more rapid or complete deficiency than when animals are supplemented continuously with retinoic acid. The general advantages of such a cycling procedure are discussed in relation to conventional means of rearing vitamin A deficient animals.