Neuroprotective effects of FK866 against traumatic brain injury: Involvement of p38/ERK pathway.

FK866 is an inhibitor of nicotinamide phosphoribosyltransferase (NAMPT), which exhibits neuroprotective effects in ischemic brain injury. However, in traumatic brain injury (TBI), the role and mechanism of FK866 remain unclear. The present research was aimed to investigate whether FK866 could attenuate TBI and clarified the underlying mechanisms. A controlled cortical impact model was established, and FK866 at a dose of 5 mg/kg was administered intraperitoneally at 1 h and 6 h, then twice per day post-TBI until sacrifice. Brain water content, Evans blue dye extravasation, modified neurological severity scores (mNSS), Morris water maze test, enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining, and western blot were performed. The results demonstrated that FK866 significantly mitigated the brain edema, blood-brain barrier (BBB) disruption, and ameliorated the neurological function post-TBI. Moreover, FK866 decreased the number of Iba-1-positive cells, GFAP-positive astrocytes, and AQP4-positive cells. FK866 reduced the protein levels of proinflammatory cytokines and inhibited NF-κB from translocation to the nucleus. FK866 upregulated the expression of Bcl-2, diminished the expression of Bax and caspase 3, and the number of apoptotic cells. Moreover, p38 MAPK and ERK activation were significantly inhibited by FK866. FK866 attenuated TBI-induced neuroinflammation and apoptosis, at least in part, through p38/ERK MAPKs signaling pathway.