The effects of thioredoxin on Nogo-A after acute spinal cord injury in rats

Abstract

Objective To observe the effects of thioredoxin (Trx) perfused through subarachnoid space on Nogo-A after acute spinal cord injury (ASCI) in rats and to probe into protective effects of Trx on ASCI. Methods Fifty-six rats were randomly divided into 3 groups: sham group (group A, n=8 ) , SCI group (group B,n =24) and Trx group (group C,n =24). The ASCI model was induced using the modified Allen technique in groups B and C. A thin plastic tube was placed in subarachnoid space below the injury level for perfusion. Rats in group C received Trx (0.75 mg/kg) from the tube everyday after injury, those in group B received the equal volume of normal saline at the same time as control, and those in group A only received vertebral laminectomy and tube placement in subarachnoid space. The BBB score was recorded at the 3rd, 7th and 14th day postinjury (n=8), then the rats were sacrificed and the injured spinal cord was taken out. Immunohistochemistry was used to detect the expression of Nogo-A and positive cells were counted at the 3rd, 7th and 14th day. Results The BBB score in group B was significantly lower than that in group A at each time point (P <0.01) , but the score in group C was significantly higher than that in group B (P<0.05 or 0.01) at the 7th and 14th day postinjury. The number of positive cells was significantly more in group B than in group A at the 7th and 14th day postoperatively (P<0.01). The number of positive cells was significantly more in group C than in group B at the 7th and 14th day postoperatively (P<0.05). Conclusion The expression of Nogo-A is notably increased in injured spinal cord. Trx can inhibit the expression of Nogo-A protein obviously, which can promote the regeneration of axon after ASCI possibly. Key words: Thioredoxin; Spinal cord injury; Nogo-A; Regenaration; Axon