Research on the Mechanism of Extra-mild Hypothermia(35℃) on neuronal cell death

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16590851
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Neurology
• Research Institution: Nippon Medical School
• Principal Investigator: KATAYAMA Yasuo Nippon Medical School, Graduate School of Medicine, Professor, 大学院・医学研究科, 教授 (70152692)
• Co-Investigator(Kenkyū-buntansha): KAMIYA Tatsushi Nippon Medical School, Department of Medicine, Assistant Professor, 医学部, 講師 (70233955)
• Project Period (FY): 2004 – 2005
• Keywords: Hypothermia / Rat / Focal Ischemia / Apoptosis / Neuronal cell death / Immunocytochemistry / In situ hybridization

Research Abstract

The aim of this study is to determine whether a rho-kinase inhibitor, fasudil, would prevent neuronal cell death and whether a extra-mild hypothermia (35℃) would enhance the neuroprotective effects of the rho-kinase inhibitor, following transient focal ischemia in rats. Sprague-Dawley rats were subjected to MCAo using an intraluminal suture technique (Nito C et al, Brain Res 1008 : 179-185, 2004) for 2hrs. The rats were reperfused for 24hrs and decapitated for infarct and edema analysis. a rho-kinase inhibitor (fasudil)-treated animals received a continuous injection of fasudil (3.0 or 10.0mg/kg) for 1hrs by after the onset of ischemia, while vehicle-treated groups received same dose of vehicle. Edaravone- treated animals received a twice injection of edaravone at the dose of 3.0mg/kg just after the onset of recirculation and 30min after. During ischemia, temporal muscle and rectal temperatures were monitored and maintained at 37℃ in the treated animals. Animals were randomly divided i nto the following four groups (each, n=10) : (I) vehicle-treated group (control) ; (II) low dose fasudil-treated group (3.0mg/kg) ; (III) high dose fasudil-treated group (10.0mg/kg) ; (IV) edaravone-treated group (3.0mg/kg x 2). Temporal muscle and rectal temperatures were maintained during ischemia at 37 ± 0.2℃. Low dose fasudil (II) ameliorated the cortical and striatal ischemic damage compared with the control (I) significantly (p<0.05), whereas high dose fasudil (III) did not decreased the cortical and striatal infarct volume significantly compared with those of groups I and II (p<0.05). Furthermore, low dose fasudil (II) also decreased the cortical and striatal edema volume significantly compared with those of control (I). These results suggest that a rho-kinase inhibitor, fasudil, has a strong neuroprotective effect compared with edaravone that has already been applied clinically in Japan, and that this drug may be a new therapeutic neuroprotective agent for the treatment of acute stroke in clinical field.