<正>Objective:To investigate the effect of neurotrophin-3 on the expressions of SOD and MDA in the injured spinal cord of rats. Methods: Totally 105 SD rats were randomly divided into 3 groups （n = 35）: sham group

control group and experimental group. Animal model of acute spinal cord was inflicted with Allen’s method by a thin plastic tube situated in subarachnoid space below the injury level for perfusion. Rats in experimental group received 20μl NT-3 （200 ng） from the tube at 0

4. 8. 12. 24 h and 3. 7 d after injury

and those in control group got the equal volume of normal saline at the same time points. The animals in sham group only received opening vertebral plate and putting tube in subarachnoid space. The rats were sacrificed at 4

8. 12. 24 h

and 3. 7

14 d postinjury （n = 5）. And the levels of superoxide dismutase （SOD） and malondialdehyde （MDA） in blood were observed with colorimetric method. Results: The serum level of SOD reduced obviously and the level of MDA raised obviously in rats after the injury

and the activity of SOD reached the lowest on day 3 and the concentration of MDA reached peak at the 7 d. In the experimental group

the SOD level was obviously higher （P<0. 01）. and MDA level was lower than the control （P<0. 01）. Conclusion:NT-3 can mitigate secondary injury of spinal cord in vivo. One of mechanisms is that inhibits abnormal expression of MDA and elevates the activity of SOD. thus the injury of free radical and lipid peroxidation is attenuated.