title: Repeated brief episodes of hypoxia modulate the calcium responses of ionotropic glutamate receptors in hippocampal neurons.
abstract: The aim of this study was to evaluate the intracellular cytosolic calcium concentration ([Ca(2+)](i)) changes induced by activation of ionotropic glutamate receptors in cultured hippocampal neurons after repeated brief episodes of hypoxia. To investigate what kinds of ionotropic glutamate receptors are involved we used specific agonists for AMPA- and NMDA-type glutamate receptors. Measurements of [Ca(2+)](i) in cultured hippocampal neurons were made by imaging Fura-2AM loaded hippocampal cells. In the rat hippocampal slice method, field potential measurements in CA1 pyramidal neurons were used. The main result of our study is that brief hypoxic episodes progressively depress the [Ca(2+)](i) increases induced by agonists of AMPA and NMDA glutamate receptors in cultured hippocampal neurons. An effectiveness of this depression is increased from the first hypoxic episode to the third one. Hypoxic preconditioning effect is observed during 10-20 min after termination of hypoxic episode and depends on [Ca(2+)](i) response amplitudes to agonists before hypoxia. In contrast to AMPA receptor activation, NMDA receptor activation before hypoxia induce the spontaneous [Ca(2+)](i) increase about 3 min after each hypoxic episode. These spontaneous [Ca(2+)](i) increases may be an indicator of the development of posthypoxic hyperexcitability in hippocampal neurons. Our results suggest that brief hypoxia-induced depression of the glutamate receptor-mediated [Ca(2+)](i) responses contributes to the development of rapid hypoxic preconditioning in hippocampal CA1 neurons.
authors: Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia.
authors: Marija V
authors: MV
authors: Turovskaya
authors: Egor A
authors: EA
authors: Turovsky
authors: Valery P
authors: VP
authors: Zinchenko
authors: Sergei G
authors: SG
authors: Levin
authors: Alina A
authors: AA
authors: Shamsutdinova
authors: Oleg V
authors: OV
authors: Godukhin
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology*; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D058468:Receptors, Ionotropic Glutamate / Q000378:metabolism*; D013997:Time Factors; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: D018690:Excitatory Amino Acid Agonists; D058468:Receptors, Ionotropic Glutamate; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D002118:Calcium