title: Estrogen attenuates oxidative stress-induced apoptosis in C6 glial cells.
abstract: We examined the mechanism of 17beta-estradiol (estrogen)-mediated inhibition of apoptosis in C6 (rat glioma) cells following exposure to hydrogen peroxide (H(2)O(2)). Cells were preincubated with 4 microM estrogen for 2 h and then exposed to 100 microM H(2)O(2) for 24 h. Exposure to H(2)O(2) caused significant increases in intracellular calcium (Ca(2+)), as determined by fura-2, which was attenuated by preincubation with estrogen. H(2)O(2) and ionomycin caused cell death in a dose-dependent manner, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Preincubation with estrogen restored viability in cells exposed to H(2)O(2) but not in cells exposed to ionomycin. Western blot analysis showed an increase in Bax/Bcl-2 ratio, calpain activity, and caspase-3 activity following treatment with H(2)O(2), and estrogen pretreatment decreased levels of all three. Cell morphology, as evaluated by Wright staining, indicated apoptosis in cells treated with H(2)O(2), and pretreatment with estrogen reduced apoptosis. Results from MTT and Wright staining were further supported by the terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP Nick End Labeling (TUNEL) assay. These results indicate a role for estrogen in preventing apoptosis in C6 glial cells exposed to H(2)O(2). Our results suggest that estrogen may have a protective role in minimizing glial cell apoptosis in neurological diseases such as demyelinating disease or central nervous system trauma.
authors.affiliation: Department of Neurology, Medical University of South Carolina, 96 Johnathan Lucas Street, Suite 309, Charleston, SC 29425, USA.
authors.forename: Pratima
authors.initials: P
authors.lastname: Sur
authors.forename: Eric Anthony
authors.initials: EA
authors.lastname: Sribnick
authors.forename: James Michael
authors.initials: JM
authors.lastname: Wingrave
authors.forename: Mark Walter
authors.initials: MW
authors.lastname: Nowak
authors.forename: Swapan Kumar
authors.initials: SK
authors.lastname: Ray
authors.forename: Naren Lal
authors.initials: NL
authors.lastname: Banik
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western / Q000379:methods; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000494:pharmacology*; D016257:Fura-2 / Q000378:metabolism; D005910:Glioma / Q000473:pathology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020287:In Situ Nick-End Labeling / Q000379:methods; D015759:Ionomycin / Q000009:adverse effects; D007476:Ionophores; D018384:Oxidative Stress / Q000187:drug effects*; D010446:Peptide Fragments / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D011960:Receptors, Estrogen; D013049:Spectrin / Q000378:metabolism; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D013997:Time Factors; D051028:bcl-2-Associated X Protein
chemical_list: C494828:Bax protein, rat; D002352:Carrier Proteins; D004967:Estrogens; D007476:Ionophores; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011960:Receptors, Estrogen; D013778:Tetrazolium Salts; D013844:Thiazoles; D051028:bcl-2-Associated X Protein; C010140:estrophilin; D013049:Spectrin; D015759:Ionomycin; D006861:Hydrogen Peroxide; D002154:Calpain; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; C022616:thiazolyl blue; D002118:Calcium; D016257:Fura-2