Activation of NR2A receptors induces ischemic tolerance through CREB signaling.
Previous exposure to a nonlethal ischemic insult protects the brain against subsequent harmful ischemia. N-methyl-D-aspartate (NMDA) receptors are a highly studied target of neuroprotection after ischemia. Recently, NMDA receptor subtypes were implicated in neuronal survival and death. We focused on the contribution of NR2A and cyclic-AMP response element (CRE)-binding protein (CREB) signaling to ischemic tolerance using primary cortical neurons. Ischemia in vitro was modeled by oxygen-glucose deprivation (OGD). Ischemic tolerance was induced by applying 45-mins OGD 24 h before 180-mins OGD. Sublethal OGD also induced cross-tolerance against lethal glutamate and hydrogen peroxide. After sublethal OGD, expression of phosphorylated CREB and CRE transcriptional activity were significantly increased. When CRE activity was inhibited by CREB-S133A, a mutant CREB, ischemic tolerance was abolished. Inhibiting NR2A using NVP-AAM077 attenuated preconditioning-induced neuroprotection and correlated with decreased CRE activity levels. Activating NR2A using bicuculline and 4-aminopiridine induced resistance to lethal ischemia accompanied by elevated CRE activity levels, and this effect was abolished by NVP-AAM077. Elevated brain-derived neurotrophic factor (BDNF) transcriptional activities were observed after sublethal OGD and administration of bicuculline and 4-aminopiridine. NR2A-containing NMDA receptors and CREB signaling have important functions in the induction of ischemic tolerance. This may provide potential novel therapeutic strategies to treat ischemic stroke.
Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan. yterasak@medone.med.osaka-u.ac.jp
Yasukazu
Y
Terasaki
Tsutomu
T
Sasaki
Yoshiki
Y
Yagita
Shuhei
S
Okazaki
Yukio
Y
Sugiyama
Naoki
N
Oyama
Emi
E
Omura-Matsuoka
Saburo
S
Sakoda
Kazuo
K
Kitagawa
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D007511:Ischemia / Q000378:metabolism*; D019194:Ischemic Preconditioning; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D017362:Cyclic AMP Response Element-Binding Protein; C120997:NR2A NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate