Effects of β-adrenergic receptor antagonists on oxidativestress in purified rat retinal ganglion cells

[摘要] Purpose: To investigate the effect of β-adrenergic receptorantagonists against oxidative stress on purified rat retinal ganglioncells (RGCs), timolol, betaxolol, carteolol and nipradilol were includedin the present study.Methods: RGCs were purified using a 2 step panning procedure frompostnatal days 6-8 using Wistar rats. After 72 h in culture under normalcondition, RGCs were exposed to oxidative stress induced by B27 mediumwithout anti-oxidant. To verify whether this stress is apoptotic ornecrotic, Annexin V and propidium iodide were used to detect apoptoticand necrotic cells after 2 h stress. The presence of a proinhibitor forintracellular cathepsin B, and an inhibitor for thiol protease(cathepsin B/H/L, calpain), was also assessed to verify necrotic celldeath event in oxidative conditions. Next, RGC cultures under oxidativestress were incubated with timolol, betaxolol, carteolol, and nipradiloladded, respectively, for 24 h culture. The RGC viability in eachcondition normalized to that under normal condition was evaluated aslive cell percentage based on total experiments of 8-15.Results: Two h after oxidative stress, Annexin V and propidiumiodide positive cells increased. Increased cell death under oxidativestress was significantly reduced by inhibitors for cathepsin or calpain.These data suggest that increased cell death under the current oxidativestress was due to necrosis. Under oxidative stress for 24 h, RGCviability reduced to 52.5-60.2% as compared with normal. With 10 nM and100 nM timolol, live cell significantly increased to 69.3% and 75.5%,respectively. Both betaxolol and nipradilol enhanced live RGCssignificantly in concentration of 100 nM and 1 μM, with viability of70.5%, 71.6%, and 70.4%, 74.7%, respectively. While with 10 nM, 100 nMand 1 μM addition of carteolol, there was no significant increase inlive RGC percentage which ranged from 53.1-55.0%.Conclusions: Timolol, betaxolol and nipradilol, but not carteolol,showed neuroprotective effects against oxidative stress induced by B27without antioxidant on purified rat RGCs at concentrations of 10 nM orhigher. Although the neuroprotective mechanism of β-blockers foroxidative stress is still unknown, this additive effect may deservefuture studies.

[学科分类] 生物化学/生物物理