Comparative pharmacological actions of N-acetylcysteine and L-cysteine on excitatory neurotransmission in bovine isolated retina (1060.4)

There is evidence that L-cysteine, the substrate for biosynthesis of hydrogen sulfide (H2S) can regulate potassium (K+)-evoked glutamate release from bovine isolated retina. In the present study, we compared the pharmacological effects of the precursor for L-cysteine, N-acetyl cysteine (NAC) to that of L-cysteine on K+-evoked [3H]D-aspartate release, and on glutamate-induced neurotoxicity in bovine isolated retina. Isolated neural retina were incubated in oxygenated Krebs solution containing 200 nM of [3H]D-aspartate and then prepared for studies of neurotransmitter release. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to assess retinal neuron survival. Both L-cysteine (0.1 µM to 10 µM) and NAC (10 µM to 1 mM) elicited a concentration-dependent inhibition of K+-induced [3H]D-aspartate release. At an equimolar concentration of 10 µM, both L-cysteine and NAC reduced [3H]D-aspartate release by 54.3% (p < 0.001) and 8.3%, respectively. Interestingly, L-cysteine (1 mM) ...