Purpose. Intraocular injection of bFGF delays photoreceptor degeneration in the Royal College of Surgeons rat, and reduces photoreceptor damage produced by constant light exposure in albino rats. In the present work, we show that bFGF upregulates bFGF expression in cultured rat Müller cells, and the up-regulation ocurrs through activation of protein kinase C (PKC). Methods. Müller cells from 1-3 day Sprague-Dawley rats were isolated and cultured with Eagle MEM + 10% FCS. Cells or passage 1-4 were treated with bFGF, PKC inhibitor H-7, or PKC activator PMA. Northern blot analysis was performed to determine bFGF mRNA levels. Results. Cells were identified by immunocytochemistry with antibodies against Müller cell markers: vimentin, carbonic anhydrase C, and glutamine synthetase. The bFGF-induced up-regulation of bFGF mRNA increased by 2.0-fold at a bFGF concentration of 1 ng/ml, 3.9-fold at 10 ng/ml, 3.7 fold at 50 ng/ml, and declined to 2.5-fold at 100 ng/ml. The time course of induction revealed a 2-fold increase in bFGF mRNA 2 hr after bFGF treatment, which reached 3.6-fold by 4 hr, 4.7-fold by 8 hr, and then declined to 3.5-fold by 24 hr. This bFGF-induced up-regulation of bFGF mRNA was completely blocked by the PKC inhibitor H-7 at a concentration of 30 μM. In addition, at this concentration, H-7 inhibited baseline expression of bFGF in cultured Müller cells. The PKC activator PMA (200 nM) also up-regulated bFGF gene expression, and the effects of bFGF and PMA were not additive. Conclusion. Our results indicate bFGF induces bFGF expression in cultured Müller cells, and the induction seems to be through PKC activation. These findings raise the possibility that exogenous bFGF promotes photoreceptor survival, in part, by stimulating Müller cell bFGF expression in vivo.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience