Involvement of Shh/Gli1 signaling in the permeability of blood-spinal cord barrier and locomotion recovery after spinal cord contusion.

Shh/Gli1 signaling plays important roles in development of spinal cord. How it is involved in spinal cord injury (SCI) remains unclear. In this study, we explored the roles of Shh/Gli1 signaling in SCI by using Shh signaling reporter Gli1lz mice and Gli1 mutant Gli1lz/lz mice. For detecting the Shh/Gli1 signaling after SCI, X-gal staining and double-immunostaining of Shh/PDGFR-β, Shh/GFAP and LacZ/GFAP was conducted at 3 days post injury (dpi) on Gli1lz mice. To investigate the effects of Gli1 mutation on pathological changes after SCI, astrocytic proliferation and the content of intra-parenchymal Evans Blue were evaluated at 7dpi in wild-type and Gli1lz/lz mice. Furthermore, locomotor recovery was assessed by BMS scoring at 1, 3, 5 and 7dpi. The results of X-gal staining and immunohistochemistry showed that Shh/Gli1 signaling was mainly activated in reactive astrocytes after SCI. The 5-bromo-2-deoxyuridine (BrdU) incorporation assay showed that mutation of Gli1 did not affect the proliferation of astrocytes. However, the leakage of Evans Blue was significantly increased in the injured cord of Gli1lz/lz mice compared to wild-type mice. In addition, locomotor recovery was significantly impaired in the Gli1lz/lz mice. The findings demonstrated that Shh/Gli1 signaling could be induced in reactive astrocytes by SCI, and plays important role in permeability of blood-spinal cord barrier (BSCB) and locomotor recovery after SCI.