Alteration of GABA system in frog retina following short light and dark adaptations - a quantitative comparison with retinal taurine.

Effect of short light and dark adaptations on retinal GABA and taurine was studied using bull frog (Rana catesbiana). The retinal GABA was increased significantly in light-adapted state, and this increase was accompanied by the increases of L-glutamate decarboxylase (GAD) activity and [3H]-GABA release. The activation of retinal GABA-transaminase succinic semialdehyde dehydrogenase (GABA-T:SSADH) was also observed after a lag period of several hours. Under the same experimental conditions, however, no significant changes were noted in retinal taurine content and cysteine sulfinate decarboxylase (CSD) activity. These findings suggest that a short light adaptation induces differential effects on retinal GABA and taurine, and the activation of GABAergic neurons in the retina may be involved in the process of short light adaptation.