[Interaction of vitamin A and zinc in lactating rats. Experimental deficiency model].

An experimental deficiency model of vitamin A and zinc in lactating rats was developed. The experimental design consisted in a depletion period of 4 weeks immediately after birth where test group animal received a casein based feed, deficient in zinc and vitamin A, and a control feed according to the recommendations of the Committee on Laboratory Animal Diets. Female Rathus norvergicus, var albinus (Rodentia, Mammalia) with 6 young males each were used. These came from the Biotério of the Faculdade de Ciências, Farmacêuticas of USP. At the end of the depletion period it was found that the weight of the males control group (109.1 g +/- 3.9 g) was significantly greater than that of the test group (40.8 g +/- 6.7 g). The same was true for the concentration of zinc in the femurs of these animals, in the control group the concentration was significantly greater (115.7 micrograms/g +/- 5.4 micrograms/g) than in the test group (35.5 micrograms/g +/- 3.3 micrograms). The concentration of vitamin A in the plasma of the control group (31.5 micrograms/dL +/- 2.5 micrograms/dL) also was significantly greater than the test group animals (8.9 micrograms/dL +/- 3.4 micrograms/dL). The concentration of hepatic vitamin A was similar for both groups. We can conclude that there was interaction of zinc and vitamin A, by liver and depletion in zinc. Although the plasmatic concentration of vitamin A indicates a depletion, this cannot be considered as total because of the hepatic reserves.