title: Attenuation by PACAP of glutamate-induced neurotoxicity in cultured retinal neurons.
abstract: The effects of pituitary adenylate cyclase activating polypeptides (PACAPs: PACAP27, PACAP38) on glutamate-induced neurotoxicity were examined using cultured retinal neurons obtained from 3- to 5-day old Wistar rats. Cell viability was evaluated by double staining with fluorescein diacetate and propidium iodide. Effects of PACAPs on the increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in retinal neurons was investigated using the Ca(2+) image analyzing system with fura-2. The cAMP contents and the mitogen-activated protein (MAP) kinase activity in retinal cultures were measured by radioimmunoassay. Concomitant application of PACAPs (10 nM-1 microM) with glutamate (1 mM) for 10 min inhibited the delayed death of retinal neurons, which was observed 24 h after glutamate (1 mM) treatment in a dose-dependent manner. Protection by PACAPs (100 nM) against glutamate-induced neurotoxicity was antagonized by PACAP6-38 (1 microM), a PACAP antagonist, and H-89 (1 microM), a protein kinase A (PKA) inhibitor. However, PACAPs did not affect the glutamate-induced increase in [Ca(2+)](i), but PACAPs (1-100 nM) increased the cAMP levels in a dose-dependent manner. In addition, activation of MAP kinase by PACAP38 (1 microM) was inhibited by simultaneous application with H-89 (1 microM). These findings suggest that PACAPs attenuate glutamate-induced delayed neurotoxicity in cultured retinal neurons by activating MAP kinase through the activation of cAMP-stimulated PKA.
authors.affiliation: Department of Ophthalmology, Hiroshima University School of Medicine, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shoge
authors.forename: H K
authors.initials: HK
authors.lastname: Mishima
authors.forename: T
authors.initials: T
authors.lastname: Saitoh
authors.forename: K
authors.initials: K
authors.lastname: Ishihara
authors.forename: Y
authors.initials: Y
authors.lastname: Tamura
authors.forename: H
authors.initials: H
authors.lastname: Shiomi
authors.forename: M
authors.initials: M
authors.lastname: Sasa
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D018698:Glutamic Acid / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000633:toxicity*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: C495403:Adcyap1 protein, rat; D018691:Excitatory Amino Acid Antagonists; D009479:Neuropeptides; D018696:Neuroprotective Agents; D009498:Neurotoxins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018698:Glutamic Acid; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium