Myelotomy reduces spinal cord edema and inhibits aquaporin-4 and aquaporin-9 expression in rats with spinal cord injury.

OBJECTIVE

Spinal cord edema contributes to the pathophysiological mechanisms underlying spinal cord injury (SCI) and is associated with functional recovery after SCI. Early myelotomy may be a promising surgical intervention for reducing SCI-induced edema. However, it remains unclear whether myelotomy can reduce SCI-induced edema. In addition, aquaporin-4 (AQP4) and aquaporin-9 (AQP9) have important roles in the regulation of water homeostasis. Here, we aimed to determine the effects of myelotomy on AQP4 and AQP9 expression and spinal cord edema in a rat model of moderate SCI.

METHODS

Rats were randomly assigned to three groups: the sham control group (n=22) receiving laminectomy alone; the contusion group (n=44) receiving laminectomy plus contusion; and the myelotomy group (n=44) receiving laminectomy plus contusion followed by myelotomy at 24 h. Functional recovery was estimated by the open-field and inclined plane tests. Spinal cord edema was determined by measuring the water content. The expression of AQP4 and AQP9 was determined by western blot.

RESULTS

Compared with the contusion group, myelotomy significantly improved the Basso, Beattie and Bresnahan scores in the open-field test and resulted in a higher mean angle value in the incline plane test. Myelotomy significantly reduced SCI-induced edema at 4 and 6 days after SCI, which was accompanied by downregulation of AQP4 and AQP9 expression.

CONCLUSION

Myelotomy improves locomotor function, reduces edema in rats with SCI and is associated with decreased expression of AQP4 and AQP9.