title: Hydrogen peroxide-induced oxidative stress in MC3T3-E1 cells: The effects of glutamate and protection by purines.
abstract: Glutamate has toxic effects on a number of tissues, partly by inducing toxic (e.g., oxidative) stress, whereas adenosine can be protective. Since there is evidence that glutamate and adenosine receptors are present in bone, we set out to study whether oxidative stress, induced by hydrogen peroxide (H2O2), affected viability in the MC3T3-E1 osteoblast-like cell line and whether treatment with adenosine receptor ligands attenuated this. Hydrogen peroxide (100 microM to 5 mM) reduced the viability of the MC3T3-E1 cells, while catalase reversed this cell loss and itself had some mitogenic effect. Superoxide dismutase (SOD) increased the number of viable cells alone but failed to modify significantly the effect of H2O2 treatments. Glutamate (100 microM, 1 mM) and NMDA (10 microM), applied alone for up to 1 h, had a mitogenic effect (P < 0.05). Adenosine A1 and A2A receptor agonists and antagonists at low and high concentrations showed some mitogenic effects when added singly, but only high concentrations of the agonists showed significant protection against cell death resulting from H2O2 treatments. Contributions from both apoptotic and necrotic pathways were implicated in the H2O2-induced cell loss as was demonstrated by the use of the caspase-3 inhibitor (Z-DEVD-fmk) and the PARP-1 inhibitor (DPQ). The results demonstrate that hydrogen peroxide was toxic to MC3T3-E1 cells, whereas glutamate was not and may even have a trophic influence. Adenosine and its receptors afforded some protection to osteoblasts against cellular death mediated partly by apoptosis and partly by necrosis.
authors.affiliation: Institute of Biomedical and Life Sciences, Division of Neuroscience and Biomedical Systems, West Medical Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
authors.forename: Amos A
authors.initials: AA
authors.lastname: Fatokun
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Stone
authors.forename: Robert A
authors.initials: RA
authors.lastname: Smith
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005971:Glutamates / Q000378:metabolism*; D005994:Glycerophosphates / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D018384:Oxidative Stress; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011687:Purines; D017470:Receptors, Glutamate / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism
chemical_list: D005971:Glutamates; D005994:Glycerophosphates; D008024:Ligands; D011687:Purines; D017470:Receptors, Glutamate; D018047:Receptors, Purinergic P1; D006861:Hydrogen Peroxide; D002374:Catalase; D011065:Poly(ADP-ribose) Polymerases; D000469:Alkaline Phosphatase; D020169:Caspases; D001205:Ascorbic Acid