DEPRESSION OF THE ELECTRORETINOGRAM IN RATS DEFICIENT IN ZINC AND TAURINE DURING PRENATAL AND POSTNATAL LIFE

The objective of this this study was to investigate whether zinc inter acts with taurine to influence the development of the electroretinogra m. 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 zi nc (50 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 level s of taurine (2 or 0 mu mol/g). Guanidinoethyl sulfonate (10 g/L), a s tructural analogue of taurine, was added to the drinking water of the animals receiving 0 mu mol/g taurine. At postnatal day 23, male pups ( n = 10) were weaned onto their respective diets. Dark-adapted electror etinograms were recorded as a function of stimulus intensity on 7 1/2- 8 1/2-week-old anesthetized pups. Two-factor analysis of variance demo nstrated no interaction between zinc and taurine for a- or b-wave ampl itudes or latencies (P < 0.05). Zinc and taurine deficiencies each ind ependently depressed electroretinogram a-wave and b-wave amplitudes bu t not latencies. The amplitude of the b-wave was plotted as a function of log stimulus intensity, and an iterative curve-fitting procedure w as used to determine the maximum response, slope, and half-saturation constant. No interaction was noted. A significant treatment effect on maximum response was demonstrated for zinc (P = 0.0498) and taurine (P = 0.0014). No treatment effects were evident for the half-saturation constant or slope. These findings indicate that zinc and taurine defic iencies are not synergistic in their depressing effects on the electro retinogram in this model. (C) Elsevier Science Inc. 1998.