Zinc and taurine interactions in maternofetal metabolism

It was proposed that zinc reproductive outcome in the rat. guanidinoethyl sulfonate (GES), and taurine interact in vivo to influence The effect of taurine deficiency induced by a taurine transport antagonist, on fetal development was examined. Female Sprague-Dawley rats were mated overnight and assigned to 1 of 4 treatments through gestation. Animals received taurine-restricted diet and 0.5% 1.0% or 2.0% GES in drinking water. Control animals received taurine-adequate diet and no GES. Taurine deficiency produced a sharp decline in maternal and fetal liver taurine (~~0.0bu5t )di d not - result in intrauterine growth retardation or significant external, visceral or skeletal malformations. It was evident that reproductive outcome might be an inadequate endpoint to explore this interaction. Instead, development of eye structure and function was examined. Virgin female Sprague-Dawley rats were bred overnight and assigned to 1 of 4 treatments in a 2 x 2 factorial design with two levels of zinc (50 or 15 pglg through gestation; 50 or 7.5 pglg after parturition) and two levels of taurine (2 or 0 prnollg). GES (1 % wlv) was provided in drinking water to the animals receiving 0 pmollg taurine. A fifth group, fed control diet, was pairfed to the marginally zinc-deficient group. At postnatal day 23, male pups were weaned onto their respective diets. Analysis of plasma zinc, tibia1 zinc and liver taurine concentrations at 7%8W weeks showed an interaction in these tissues. Dark-adapted oscillatory potentials (OPs) and electroretinograms (ERG) were recorded. Two-way ANOVA revealed a significant interaction between zinc and taurine for OP, and OP, amplitudes. - ERG b-wave amplitude as a function of log stimulus intensity was plotted and an iterative curve fitting procedure used to determine the maximum response (Vmax), slope (n) and half-saturation constant (0).N o interaction was noted. Zinc or taurine deficiency each independently depressed Vmax. Zinc deficiency depressed the amplitude of OP,; taurine depletion similarly affected the amplitude of OP,, OP, and OP,. Histological examination of the retinas from animals deficient in both zinc and taurine revealed photoreceptor degeneration and retinal dysplasia. These data provide evidence that zinc and taurine interact physiologically and influence retinal function.