OSCILLATORY POTENTIALS AND LIGHT-MICROSCOPIC CHANGES DEMONSTRATE AN INTERACTION BETWEEN ZINC AND TAURINE IN THE DEVELOPING RAT RETINA

Our objective was to investigate whether zinc interacts with taurine t o influence the development of retinal structure and function, Virgin female Sprague-Dawley rats were bred overnight and assigned to one of four treatments in a 2 x 2 factorial design with two levels of zinc (5 0 mu g/g through gestation and 50 mu g/g after parturition; 15 mu g/g through gestation and 7.5 mu g/g after parturition) and two levels of taurine (2 or 0 mu mol/g). The control diet contained 50 mu g/g zinc a nd 2 mu mol/g taurine. Guanidinoethyl sulfonate (10 g/L), a taurine tr ansport inhibitor, was added to the drinking water of the rats receivi ng 0 mu mol/g taurine. Al postnatal d 23, male pups (n = 10) were wean ed onto their respective diets, Pup eyes were examined by biomicroscop e and indirect ophthalmoscope al 4 and 7 wk; retinal folds and choroid al atrophy were detected in the pups deficient in zinc and taurine, An alysis of plasma zinc and tibial zinc concentrations revealed a signif icant interaction in these tissues (P < 0.05). Dark-adapted oscillator y potentials (OP) were recorded at 7.5-8.5 wk. Two-way ANOVA showed a significant interaction between zinc and taurine for OP2 and OP3 ampli tudes; marginal zinc deficiency decreased the amplitude of the OP only when rats were also deficient in taurine. A significant depressing ef fect of marginal zinc deficiency was noted for OP1 amplitude. Taurine deficiency significantly depressed the amplitude of OP1 and OP4. Histo logical examination of the retinas from rats deficient in both zinc an d taurine revealed photoreceptor degeneration and confirmed retinal dy splasia. These data provide evidence for an interaction between zinc a nd taurine in retinal morphology and function.