Blood-borne macromolecule induces FGF receptor gene expression after focal ischemia

We have detected fibroblast growth factor receptor (FGFR) gene expression in the focal ischemia model. The FGFR gene expression in neurons can be explained by neuronal network disturbances, but the mechanism of astroglial gene expression remains uncertain. We speculated that blood-borne edema fluid may activate gene expression of astroglias. To prove this hypothesis, we compared the pattern's of gene expression of FGFR and distribution of edema fluid by using serial tissue sections of the middle cerebral artery (MCA) ischemia. The left MCA of twenty-four male Wistar rats were occluded, and sacrificed 1, 3, 4, 7 and 14 days later by transcardiac perfusion and fixation. The tissues were sliced thinly to 14 microns sections. Part of the tissue sections was used for in situ hybridization for rat FGFR with [35S]labeled RNA probes. The other part of the sections was used for immunostaining for albumin, immunoglobulin G (IgG) and IgM. The FGFR mRNA expression was evident in the lesion-side hemisphere. In the cortex, neurons mainly expressed FGFR gene in the cortex, whereas astroglias and capillary endothelium expressed FGFR in the corpus callosum and internal capsule. The albumin distributed cortex and white matter of the lesion-side and it extended to the contralateral side. The IgG distributed mainly in the lesion-side white matter, and in part extended to the contralateral side. The IgM only distribute to the infarcted area. When we compared topographical distribution of FGFR in the white matter and pattern of albumin, IgG and IgM distribution, pattern of IgG distribution correlated well to the area of FGFR expression.(ABSTRACT TRUNCATED AT 250 WORDS)