Fibroblast growth factors preserve blood-brain barrier integrity through RhoA inhibition after intracerebral hemorrhage in mice.

Acid fibroblast growth factor (FGF1) or basic fibroblast growth factor (FGF2) was administered intracerebroventricularly (ICV) at 0.5 hours after intrastriatal injection of bacterial collagenase (cICH) or autologous whole blood (bICH). Fibroblast growth factor receptor (FGFR) inhibitor PD173074 and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 were additionally administered with FGF2. The selective Rho–associated coiled-coil forming protein serine/threonine kinase (ROCK) inhibitor Y27632 was independently administered at 0.5 hours after cICH. Brain water content and neurofunctional deficits were evaluated at 24 and 72 hours after ICH induction. Evans blue extravasation as well as Western blot analysis for the quantification of activated FGFR, Akt, Ras-related C3 botulinum toxin substrate 1 (Rac1), Ras homolog gene family member A (RhoA) and adherens junction proteins (p120-catenin, β-catenin and VE-cadherin) were conducted at 72 hours post-cICH. FGF treatment reduced perihematomal brain edema and improved neurofunctional deficits at 72 hours after experimental ICH (p<0.05, compared to vehicle); however, FGFR and PI3K inhibition reversed these neuroprotective effects. Exogenous FGF2 increased activated FGFR, Akt, and Rac1 but reduced activated RhoA protein expression at 72 hours after cICH (p<0.05, compared to vehicle), which was reversed by FGFR and PI3K inhibition. Y27632 treatment reduced brain injury at 72 hours after cICH (p<0.05, compared to vehicle) and increased the expression of catenins (p120-catenin, β-catenin). In conclusion, our findings suggest that exogenous FGF treatment reduced RhoA activity via FGFR-induced activation of the PI3K-Akt-Rac1 signaling pathway, thus preserving BBB integrity, and therefore attenuating secondary brain injury after experimental ICH in mice.