PURPOSE:To standardize a new method for assessing cataractogenesis in isolated cultured bovine lenses using L-cysteine as the standard anti-cataract agent. METHODS:Intact bovine lenses were cultured in DMEM with L-cysteine in presence or absence of hydrogen peroxide (H2O2). Lens opacity (transmittance) was determined using a plate reader. Lens homogenate glutathione (GSH) and superoxide dismutase (SOD) contents were measured using enzyme immunoassays kits. RESULTS:DMEM-cultured lenses exhibited a time-dependent loss in transmittance (230-710 nm) up to 120 h, achieving the highest reduction of 38.6 ± 0.09% at 420 nm (p < .001;n = 12). Compared to untreated lenses (time in hours [t] = 0), L-cysteine (10-6 M and 10-5 M) significantly (p < .001;n = 6) increased time-dependent transmittance (420 nm) by 31.6 ± 0.17% and 28.0 ± 0.07%(t = 120), respectively. When compared to DMEM-cultured lenses (t = 0), H2O2 (10 mM, 50 mM and 100 mM) significantly (p < .001;n = 12) reduced transmittance by 57.8 ± 0.1, 57.4 ± 0.04 and 87.7 ± 0.6%(t = 120), respectively. Moreover, L-cysteine significantly (p < .001;n = 6) attenuated H2O2 (50 mM)-induced decrease in transmittance by 12.5 ± 0.05%(10-6 M), 13.0 ± 0.09%(10-5 M), 14.5 ± 0.08%(10-4 M) and 8.6 ± 0.11%(10-3 M)(t = 120), respectively. When compared to untreated lenses (t = 0), the time-dependent decrease (p < .001;n = 5) in lenticular total GSH content and total SOD activity of 46.1 ± 0.06% and 42.0 ± 1.65% (t = 120) was attenuated (p < .001;n = 5) by L-cysteine (10-6 M) by 76.6 ± 0.06% and 7.4 ± 1.98%, respectively. Similarly, the H2O2(50 mM)-induced decline (p < .001; n = 5) in total GSH content and SOD activity of 82.6 ± 0.08% and 86.6 ± 0.66% (t = 120) was attenuated by L-cysteine (10-4 M) by 74.7 ± 1.05% and 161.1 ± 4.9%, respectively. CONCLUSION:Measurement of spectral transmission coupled with assessment of the activity of antioxidant enzymes in bovine cultured lens can provide a useful tool in studies of cataracts in an animal model of this disease.

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) and NAC (1 µM) attenuated glutamate (12 mM)‐induced neuron degeneration by 31.1% (p<0.05) and 18.4%, respectively. L‐cysteine was more potent in attenuating neurotransmitter release while NAC was more effective in preventing glutamate‐induced toxicity suggesting that these compounds mediate their pharmacological actions via different mechanisms.