title: 17beta-estradiol attenuates glutamate-induced apoptosis and preserves electrophysiologic function in primary cortical neurons.
abstract: Glutamate toxicity causes neuronal death in neurodegenerative diseases; hence, there is a need for therapeutic agents rendering functional neuroprotection. We tested the effects of 17beta-estradiol (estrogen) in rat primary cortical neurons after glutamate exposure. Wright staining and ApopTag assays indicated that 0.5 microM glutamate for 24 hr caused apoptosis. Glutamate-induced apoptosis correlated with upregulation of calpain, a proapoptotic shift in the Bax:Bcl-2 ratio, and increased activation of caspase-3. Pretreatment with 10 nM estrogen prevented apoptosis, attenuated calpain upregulation, shifted the Bax:Bcl-2 ratio toward survival, and decreased caspase-3 activation. Single-cell voltage-clamp techniques were used to record whole-cell currents associated with Na+ channels, N-methyl-D-aspartate receptor channels, and kainate receptor channels. No significant differences were recorded in membrane capacitance at -70 mV in neurons treated with estrogen or estrogen plus glutamate, relative to controls. Notably, no changes in capacitance indicated that neurons treated with estrogen and glutamate did not experience apoptosis-associated cell shrinkage. No membrane potential could be recorded in the neurons treated with glutamate due to apoptosis. All recorded currents were similar in amplitude and activation/inactivation kinetics in control neurons and neurons treated with estrogen plus glutamate. Estrogen thus preserved both neuronal viability and function in this in vitro glutamate toxicity model.
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Eric Anthony
authors.initials: EA
authors.lastname: Sribnick
authors.forename: Swapan Kumar
authors.initials: SK
authors.lastname: Ray
authors.forename: Mark Walter
authors.initials: MW
authors.lastname: Nowak
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Naren Lal
authors.initials: NL
authors.lastname: Banik
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western / Q000379:methods; D002154:Calpain / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004347:Drug Interactions; D004594:Electrophysiology; D004958:Estradiol / Q000494:pharmacology*; D018698:Glutamic Acid / Q000633:toxicity*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018408:Patch-Clamp Techniques / Q000379:methods; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D015222:Sodium Channels / Q000187:drug effects; D051028:bcl-2-Associated X Protein
chemical_list: D002154:Calpain; D053148:Caspase 3; D020169:Caspases; D004958:Estradiol; D018698:Glutamic Acid; D016376:Oligonucleotides, Antisense; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D015222:Sodium Channels; D051028:bcl-2-Associated X Protein; C494828:Bax protein, rat; C505410:Casp3 protein, rat