Hydrogen Peroxide Affects the Electroretinogram of Isolated Perfused Rat Retina

To evaluate the effects of H₂O₂ as an oxidant on the electroretinogram (ERG) in isolated rat retina.

Retinas were isolated from rat eyes and perfused with a nutrient solution. ERGs were recorded every 3 min. Once the signal was at a steady state, H₂O₂ was added to the perfusion solution.

H₂O₂ caused instantaneous and transient changes in amplitudes and implicit times of the ERG, followed by changes in retinal survival curves. H₂O₂ 0.2 mM produced a rapid increase in b-wave amplitude, followed by a return to the initial value and a survival curve above the control (without H₂O₂). A slight increase in a-wave was observed, followed by a decrease and a recovery above the control. The slow PIII decreased and then recovered to the initial value. H₂O₂ 0.6 mM induced a small increase in b-wave amplitude, followed by a rapid decrease without recovery. The a-wave and slow PIII decreased rapidly without recovery. The implicit times of the a-wave and b-wave increased moderately with a low dose of H₂O₂, whereas they significantly increased with a high dose. Whatever the dose, the slow PIII implicit time increased significantly, followed by a return to the initial value. Barium increased the a-wave and b-wave, and then H₂O₂ reduced the two waves with a stronger effect on the a-wave. Aspartate and barium isolated the fast PIII, which decreased after H₂O₂ application.

H₂O₂ affects retinal function as shown by ERGs in isolated rat retina. The response differs with the dose of H₂O₂, suggesting that mechanisms underlying the action at low doses might be different from those at high doses. Our results also suggest an effect of H₂O₂ on ionic currents and/or neurotransmitter releases involved in the generation of the ERG and indicate a more pronounced effect on photoreceptors than on postsynaptic cells.