title: Protective mechanism of agmatine pretreatment on RGC-5 cells injured by oxidative stress.
abstract: Agmatine has neuroprotective effects on retinal ganglion cells (RGCs) as well as cortical and spinal neurons. It protects RGCs from oxidative stress even when it is not present at the time of injury. As agmatine has high affinity for various cellular receptors, we assessed protective mechanisms of agmatine using transformed RGCs (RGC-5 cell line). Differentiated RGC-5 cells were pretreated with 100 muM agmatine and consecutively exposed to 1.0 mM hydrogen peroxide (H2O2). Cell viability was determined by measuring lactate dehydrogenase (LDH), and the effects of selective alpha 2-adrenergic receptor antagonist yohimbine (0-500 nM) and N-methyl-D-aspartic acid (NMDA) receptor agonist NMDA (0-100 microM) were evaluated. Agmatine's protective effect was compared to a selective NMDA receptor antagonist MK-801. After a 16-h exposure to H2O2, the LDH assay showed cell loss greater than 50%, which was reduced to about 30% when agmatine was pretreated before injury. Yohimbine almost completely inhibited agmatine's protective effect, but NMDA did not. In addition, MK-801 (0-100 microM) did not significantly attenuate the H2O2-induced cytotoxicity. Our results suggest that neuroprotective effects of agmatine on RGCs under oxidative stress may be mainly attributed to the alpha 2-adrenergic receptor signaling pathway.
authors.affiliation: Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Y
authors.initials: Y
authors.lastname: Iizuka
authors.forename: S
authors.initials: S
authors.lastname: Hong
authors.forename: C Y
authors.initials: CY
authors.lastname: Kim
authors.forename: W I
authors.initials: WI
authors.lastname: Yang
authors.forename: J E
authors.initials: JE
authors.lastname: Lee
authors.forename: G J
authors.initials: GJ
authors.lastname: Seong
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000376:Agmatine / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D018696:Neuroprotective Agents; D000376:Agmatine