Increased ICP promotes CaMKII-mediated phosphorylation of neuronal NOS at Ser⁸⁴⁷ in the hippocampus immediately after subarachnoid hemorrhage.
Early brain injury has recently been identified as an indicator of poor prognosis after subarachnoid hemorrhage (SAH). Calmodulin-dependent protein kinase IIα (CaMKIIα) has been shown to phosphorylate neuronal NOS (nNOS) at Ser(847), resulting in a reduction in nNOS activity. In this study, we revealed chronological changes in the phosphorylation of nNOS at Ser(847) in the hippocampus and cortex immediately after SAH. In a rat single-hemorrhage model of SAH, the hippocampus and adjacent cortex were collected up to 24h after SAH. Samples from rats that were not injected with blood were used as controls. NOS was partially purified from the crude samples using ADP-agarose affinity chromatography. Western blot analysis revealed that nNOS phosphorylated (p-nNOS) at Ser(847) was significantly increased in the hippocampus, but not in the cortex, at 1h after SAH compared with that resulting from the control treatment. Immunoreactivity of p-nNOS at Ser(847) was observed in interneurons of the hippocampus at 1h after SAH. Injection of saline instead of blood also significantly induced p-nNOS at Ser(847) levels in the hippocampus at 1h after injection. The colocalization of CaMKIIα and nNOS was transiently increased in the hippocampus at 0.5h after SAH. Our data suggest that immediately after SAH, an increase in intracranial pressure might induce transient cerebral ischemia, potentially promoting the phosphorylation of nNOS at Ser(847) by CaMKIIα in the hippocampus. The activation of p-nNOS at Ser(847) in the hippocampus may alleviate ischemic insults immediately after SAH to exert a neuroprotective effect against early brain injury.
Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Aichi, Japan.
Kazushige
K
Makino
Department of Neurological Surgery, Aichi Medical University, Nagakute 480-1195, Aichi, Japan. Electronic address: kosuka@aichi-med-u.ac.jp.
Koji
K
Osuka
High Technology Research Center, Pharmacology, Showa Pharmaceutical University, Machidashi 194-8543, Tokyo, Japan.
Yasuo
Y
Watanabe
Department of Anatomy II, Fujita Health University School of Medicine, Toyoake 470-1192, Aichi, Japan.
Nobuteru
N
Usuda
Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Aichi, Japan.
Masahito
M
Hara
Department of Neurological Surgery, Aichi Medical University, Nagakute 480-1195, Aichi, Japan.
Masahiro
M
Aoyama
Department of Neurological Surgery, Aichi Medical University, Nagakute 480-1195, Aichi, Japan.
Masakazu
M
Takayasu
Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Aichi, Japan.
Toshihiko
T
Wakabayashi
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000502:physiology; D006624:Hippocampus / Q000473:pathology*; D019586:Intracranial Hypertension / Q000503:physiopathology*; D008297:Male; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D013345:Subarachnoid Hemorrhage / Q000473:pathology*; D013997:Time Factors
D012694:Serine; D052248:Nitric Oxide Synthase Type I; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2
Calmodulin-dependent protein kinase IIα; Neuronal nitric oxide synthase; Phosphorylation; Subarachnoid hemorrhage