Expression of basic fibroblast growth factor and its receptor mRNA in retinal tissue following ischemic injury in the rat

Background: Our purpose was to determine the time-dependent changes of expression of basic fibroblast growth factor (bFGF) and its receptor in pressure-induced retinal ischemia in rats. Methods: Retinal ischemia was induced in Wistar rats by increasing the intraocular pressure to 110 mmHg for 45 min by cannulation into the eyes. At the end of the ischemic period, reperfusion of the retinal vasculature was confirmed. Localization of bFGF and FGF receptor-1 (FGF-R) mRNAs were evaluated by in situ hybridization at various times after reperfusion. The reverse-transcription polymerase chain reaction (RT-PCR) method was used to detect the expression of bFGF and FGF-R mRNA in the sensory retina. Results: In normal sensory retina, bFGF and FGF-R mRNAs were observed in the ganglion cell layer and inner nuclear layer, bFGF gene expression in the sensory retina increased within 24 h, particularly at 6-12 h. FGF-R gene expression increased earlier than that of bFGF. By RT-PCR, expression of bFGF gene reached a peak at 6-24 h, and FGF-R reached a peak at 3-12 h. These RT-PCR results are comparable to those of in situ hybridization. Conclusions: These results demonstrate that transient retinal ischemia leads to the induction of bFGF mRNA synthesis, and suggest that bFGF has a protective role, e.g., a defense mechanism for the sensory retina.