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Induction of secretory phospholipase A 2 in reactive astrocytes in response to transient focal cerebral ischemia in the rat brain
Author(s) -
Lin TengNan,
Wang Qun,
Simonyi Agnes,
Chen JeanJu,
Cheung WaiMui,
Y. He Yong,
Xu Jan,
Sun Albert Y.,
Hsu Chung Y.,
Sun Grace Y.
Publication year - 2004
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2004.02540.x
Subject(s) - ischemia , in situ hybridization , glial fibrillary acidic protein , northern blot , messenger rna , phospholipase a2 , astrocyte , western blot , biology , microglia , microbiology and biotechnology , pathology , neuroglia , immunohistochemistry , chemistry , endocrinology , medicine , central nervous system , inflammation , biochemistry , immunology , enzyme , gene
Although mRNA expression of group IIA secretory phospholipase A 2 (sPLA 2 ‐IIA) has been implicated in responses to injury in the CNS, information on protein expression remains unclear. In this study, we investigated temporal and spatial expression of sPLA 2 ‐IIA mRNA and immunoreactivity in transient focal cerebral ischemia induced in rats by occlusion of the middle cerebral artery. Northern blot analysis showed a biphasic increase in sPLA 2 ‐IIA mRNA expression following 60‐min of ischemia–reperfusion: an early phase at 30 min and a second increase at a late phase ranging from 12 h to 14 days. In situ hybridization localized the early‐phase increase in sPLA 2 ‐IIA mRNA to the affected ischemic cortex and the late‐phase increase to the penumbral area. Besides sPLA 2 ‐IIA mRNA, glial fibrillary acidic protein (GFAP) and cyclo‐oxygenase‐2 mRNAs, but not cytosolic PLA 2 , also showed an increase in the penumbral area at 3 days after ischemia–reperfusion. Immunohistochemistry of sPLA 2 ‐IIA indicated positive cells in the penumbral area similar to the GFAP‐positive astrocytes but different from the isolectin B4‐positive microglial cells. Confocal microscopy further confirmed immunoreactivity of sPLA 2 ‐IIA in reactive astrocytes but not in microglial cells. Taken together, these results demonstrate for the first time an up‐regulation of the inflammatory sPLA 2 ‐IIA in reactive astrocytes in response to cerebral ischemia–reperfusion.