ID 111617
Author
Uno, Masaaki The University of Tokushima
Sato, Koichi The University of Tokushima
Morioka, Motohiro Kumamoto University
Ushio, Yukitaka Kumamoto University
Keywords
cerebral ischemia
penumbra
selective neuronal death
reperfusion
excitotoxicity
Content Type
Journal Article
Description
This article describes the pathophysiology of, and treatment strategy for, cerebral ischemia. It is useful to think of an ischemic lesion as a densely ischemic core surrounded by better perfused “penumbra” tissue that is silent electrically but remains viable. Reperfusion plays an important role in the pathophysiology of cerebral ischemia. Magnetic resonance imaging (MRI) and histological studies in rat focal ischemia models using transient middle cerebral artery (MCA) occlusion indicate that reperfusion after an ischemic episode of 2- to 3-hour duration does not result in reduction of the size of the infarct. Brief occlusion of the MCA produces a characteristic, cell-type specific injury in the striatum where medium-sized spinous projection neurons are selectively lost ; this injury is accompanied by gliosis. Transient forebrain ischemia leads to delayed death of the CA1 neurons in the hippocampus. Immunohistochemical and biochemical investigations of Ca2+/calmodulin-dependent protein kinase II(CaM kinase II) and protein phosphatase (calcineurin) after transient forebrain ischemia demonstrated that the activity of CaM kinase II was decreased in the CA1 region of the hippocampus early (6- 12 hours) after ischemia. However, calcineurin was preserved in the CA1 region until 1.5 days after the ischemic insult and then lost ; a subsequent increase in the morphological degeneration of neurons was observed. We hypothesized that an imbalance of Ca2+/calmodulin dependent protein phosphorylation-dephosphorylation may be involved in delayed neuronal death after ischemia. In the treatment of acute ischemic stroke, immediate recanalization of the occluded artery, using systemic or local thrombolysis, is optimal for restoring the blood flow and rescuing the ischemic brain from complete infarction. However, the window of therapeutic effectiveness is very narrow. The development of effective neuroprotection methods and the establishment of reliable imaging modalities for an early and accurate diagnosis of the extent and degree of the ischemia are imperative.
Journal Title
The Journal of Medical Investigation
ISSN
13431420
NCID
AA11166929
Publisher
The University of Tokushima School of Medicine
Volume
45
Issue
1-4
Start Page
57
End Page
70
Sort Key
57
Published Date
1998-08
URL ( Publisher's Version )
FullText File
language
eng
TextVersion
Publisher
departments
University Hospital
Medical Sciences