Spatial resolution of calpain-catalyzed proteolysis in focal cerebral ischemia.
Transient forebrain ischemia induces calpain-mediated degradation of the neuronal cytoskeleton, alpha-fodrin, and this results in ischemic neuronal death. In this study, we investigated the spatial distribution and temporal changes of calpain-catalyzed alpha-fodrin proteolysis in focal cerebral ischemia and examined the effects of a calpain inhibitor. Ischemia was induced in gerbils by 3-h middle cerebral artery occlusion followed by reperfusion. Animals were divided into four groups: a sham-operated group, an ischemic group, a vehicle-treated group, and a calpain inhibitor-treated group. Intravenous injections of vehicle or calpain inhibitor I were administered 30 min before ischemia. Infarct volumes were measured 1 day after reperfusion and the spatial distribution of calpain-catalyzed alpha-fodrin proteolysis was investigated by immunohistochemistry 15 min, 1 h, 4 h, and 1 day after reperfusion. Infarct volume (mean +/- SD) in the ischemic group and the vehicle-treated group was 204.6 +/- 19.1 mm3 and 212.4 +/- 16.3 mm3, respectively, and the calpain inhibitor I reduced the infarct volume [149.4 +/- 25.2 mm3 (P < 0.05)]. Immunoblot analysis demonstrated that calpain inhibitor reduced proteolysis. Ischemia induced fodrin proteolysis in the ischemic core and the peri-infarct zone within 15 min after reperfusion, with proteolysis developing quickly in the ischemic core and more slowly in the peri-infarct zone. Proteolysis preceded neuronal death in the peri-infarct zone. Calpain inhibitor I ameliorated neuronal death in the peri-infarct zone but not in the ischemic core. Thus, calpain plays a pivotal role on focal ischemia as well as in global ischemia.
Kambe
Atsushi
A
Division of Neurosurgery, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, Yonago, Japan. kanimo@grape.med.tottori-u.ac.jp
Yokota
Masayuki
M
Saido
Takaomi C
TC
Satokata
Ichiro
I
Fujikawa
Hirokazu
H
Tabuchi
Sadaharu
S
Kamitani
Hideki
H
Watanabe
Takashi
T
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002545:Brain Ischemia / Q000201:enzymology* / Q000517:prevention & control; D002154:Calpain / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002384:Catalysis / Q000187:drug effects; D005260:Female; D005849:Gerbillinae; D006023:Glycoproteins / Q000494:pharmacology / Q000627:therapeutic use; D010447:Peptide Hydrolases / Q000032:analysis / Q000378:metabolism
D006023:Glycoproteins; C039304:calpain inhibitors; D010447:Peptide Hydrolases; D002154:Calpain