Agmatine pretreatment protects retinal ganglion cells (RGC-5 cell line) from oxidative stress in vitro

Agmatine, 2-(4-aminobutyl)guanidine, has been reported to have neuroprotective effects against various neuronal damages. In this study it was investigated whether agmatine pretreatment rescues the retinal ganglion cells from oxidative injury in vitro. Alter differentiation of transformed rat retinal ganglion cells (RGC-5 cell line) with staurosporine, agmatine (0.0 to 100.0 microM) pretreatment was performed for 2 hours. Subsequently, they were exposed to hydrogen peroxide (0.0 to 2.5 mM) as an oxidative stress. Cell viability was monitored for up to 48 hours with the lactate dehydrogenase (LDH) assay and apoptosis was examined by the Terminal deoxynucleotide transferase-mediated terminal uridine deoxynucleotidyl transferase nick end-labeling (TUNEL) method. As a result, differentiated RGC-5 cells were found to have decreased viability after addition of hydrogen peroxide in a dose-dependent manner. This hydrogen peroxide induced cytotoxicity caused apoptosis characterized by DNA fragmentation. Agmatine pretreatment not only increased cell viability but also attenuated DNA fragmentation. In conclusion, agmatine pretreatment demonstrated neuroprotective effects against oxidative stress induced by hydrogen peroxide in differentiated RGC-5 cells in vitro. This suggests a novel therapeutic strategy rescuing retinal ganglion cells from death caused by oxidative injury.(AU)

Agmatine inhibits hypoxia-induced TNF-alpha release from cultured retinal ganglion cells

The effect of hypoxia on the release of tumor necrosis factor-alpha (TNF-alpha) in transformed rat retinal ganglion cells (RGCs) and the effect of agmatine on the hypoxia-induced production of TNF-alpha in RGCs were evaluated. RGCs were cultured under hypoxic conditions with 5% oxygen, with or without 100 microM agmatine. The expression levels of TNF-alpha and its receptor-1 (TNF-R1) were investigated by Western blot analysis. After 6 hours of hypoxia, we noted an increase in TNF-alpha production in RGCs. Agmatine significantly reduced TNF-alpha level after 12 hours of hypoxic treatment. The expression of TNF-R1 was not affected by the hypoxia or agmatine treatment. Our results show that agmatine inhibits the TNF-alpha production of RGCs in hypoxic condition. These results demonstrate a possible neuroprotective mechanism for agmatine against hypoxic damage in RGCs.(AU)