title: Transient increase of cyclic AMP induced by glutamate in cultured neurons from rat spinal cord.
abstract: We demonstrated that glutamate increased the cyclic AMP level in cultured neurons from rat spinal cord. A bath application of glutamate (300 microM) elicited a rapid increase of the cyclic AMP concentration reaching a level three times as high as the basal level in approximately 3 min, and its content then decreased to the control level in 15 min. The increase was not observed in a Ca(2+)-free medium and was inhibited by an antagonist of NMDA receptors or a voltage-sensitive Ca2+ channel blocker. Preincubation with W7 also inhibited the glutamate-evoked cyclic AMP increase. NMDA, aspartate, and high-K+ conditions also induced a cyclic AMP increase; however, a decreasing phase did not follow. The decreasing phase was observed when (2S,1'S,2'S)-2-(carboxycyclopropyl)-glycine, a potent agonist for metabotropic glutamate receptors, was combined with NMDA. These results suggest that the cyclic AMP increase is mediated by a Ca2+ influx via both NMDA receptors and voltage-sensitive Ca2+ channels followed by an activation of the Ca2+/calmodulin system, and the decreasing phase observed in the case of glutamate exposure is due to the activation of the metabotropic glutamate receptors.
authors.affiliation: Department of Physiology, Ehime University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tsuji
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Ogata
authors.forename: T
authors.initials: T
authors.lastname: Shibata
authors.forename: K
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology*; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002147:Calmodulin; D018690:Excitatory Amino Acid Agonists; D018094:Receptors, Metabotropic Glutamate; D013449:Sulfonamides; D018698:Glutamic Acid; C017967:W 7; D000242:Cyclic AMP; D002118:Calcium