[Expression of Semaphorin 3A after spinal cord injury]

To investigate expression of Semaphorin 3A in rats after spinal cord injury and explore possible mechanism of inhibiting of axonal regeneration after SCI.

Forty healthy female SD rats, 8 weeks old, weighing (210.00±9.88) g, were randomly divided into control group(20 rats in group A) and model group(20 rats in group B). In control group, removal of T₁₀ lamina and partial removal of T₉ and T₁₁ lamina were performed, and no further operation was performed on spinal cord (pseudo operation). In model group, the total T₁₀ and partial T₉, T₁₁ partial lamina were incised and the spinal cord transection was performed to create animal models of spinal cord injury. The rats were perfused and spinal cord tissue obtained at 3, 7, 14, 28 and 42 days after surgery (4 rats in each group at each time point), respectively, and then HE staining was performed. Meanwhile, the expression of Semaphoring 3A was detected in accordance with the protocol of SP kit.

After a simple spinal cord transection injury, hemorrhagic necrosis, localized edema, neurodegeneration, necrosis, and cyst formation occurred in the injured area, and glial scar formation occurred in glial cells. Semaphorin 3A expression levels in control group was low in the gray matter area. There was no expression of Semaphorin 3A in the injured area of spinal cord injury in model group 3 days after operation. On the 14th day, the expression of Semaphorin 3A in the injured area of spinal cord injury increased significantly and was at a high level. On the 28th day, the expression of Semaphorin 3A was moderate. On the 42th day, the positive expression of Semaphorin 3A returned to normal level.

The increased expression of Semaphorin 3A after spinal cord injury may be one of the mechanisms that inhibit axonal regeneration.