Granulocyte colony-stimulating factor protected against brain injury in a rat cerebral hemorrhage model by modulating inflammation.

Abstract

Granulocyte colony-stimulating factor (G-CSF) has been reported to exert a protective effect against secondary brain damage, but the underlying mechanisms remain unknown. We explored the ability of G-CSF to protect the brain from injury in a rat autologous blood-induced model of intracerebral hemorrhage (ICH), with a special focus on the anti-inflammation effect. An ICH was induced in 8-week-old male rats by an infusion of autologous blood, and the rats were then randomly assigned to five treatment groups: sham, ICH, and ICH+ low-dose (25 µg/kg), middle-dose (50 µg/kg), and high-dose (75 µg/kg) G-CSF. We then evaluated the levels of brain inflammation-related genes and proteins. The levels of tumor-necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) mRNA increased between days 1 and 14 post-ICH, with the highest expression on day 3. These changes were rectified by G-CSF in a dose-dependent manner. At day 3 post-injury, an elevation of the nuclear factor-kappa B (NF-κB) p65 protein level and a reduction of the inhibitor of NF-κB alpha (IκBα) protein level were observed; G-CSF treatment exerted a beneficial effect on both protein expressions. The expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins were increased; these changes were rectified by the highest dose of G-CSF. The brain-protecting effects of G-CSF are likely to be attributable, at least in part, to attenuation of the TNF-α, IL-6, iNOS, and COX-2 expressions induced by NF-κB activation in the brain tissues of this autologous blood-induced ICH rat model.