Sulphoraphane enhances aquaporin-4 expression and decreases spinal cord oedema following spinal cord injury

Background: Aquaporin-4 (AQP4) is a water channel protein and it is an important determinant of outcome after brain injury. Sulphoraphane (SFN) increases AQP4 levels with reduction of brain oedema at 3 days post-traumatic brain injury. However, little is known about the effect of SFN on AQP4 expression and oedema after spinal cord injury (SCI). Methods and procedures: The present study used a murine SCI model induced by compression injury. AQP4 protein level and mRNA level were detected by Western blot and by RT-PCR at 48 hours after SCI, respectively. In addition, immunohistochemical study was used to show AQP4 expression in the spinal cord segments and water content of the spinal cord segments were measured by wet : dry weight ratio. Main outcomes and results: This study shows that AQP4 level was decreased in the injured spinal cord segments at 48 hours following SCI. Post-injury administration of SFN increased AQP4 levels, which was accompanied by a significant reduction in spinal cord segment oedema at 48 hours post-injury. Conclusion: These findings suggest that the reduction of spinal cord oedema in response to SFN administration could be due, in part, to water clearance by AQP4 from the injured spinal cord segments.