THE EFFECT OF COLLAGENASE ON THE HYPERALGESIA INDUCED BY NUCLEUS PULPOSUS ALLOGRAFTED INTO EPIDURAL SPACE IN RATS

Objective: To observe the effects of collagenase on the hyperalgesia induced by nucleus pulposus allografted into epidural space in rats.Methods: Eighteen male Sprague-Dawley rats were randomly divided into three groups with 6 rats in each: fat + collagenase group (FE group), nucleus pulposus + normal saline group (NS group) and nucleus pulposus + collagenase group (NE group). The allografted fat and nucleus pulposus were acquired from other 9 male SD rats. Fat (approximately 3~4 mg)+collagenase (20 μl, 1.25×104 u/ml), nucleus pulposus (approximately 3～4 mg)+normal saline (20 μl), and nucleus pulposus (approximately 3~4 mg)+collagenase (20 μl, 1.25×104 u/ml) were implanted into L6~S1 epidural space in FE, NS and NE groups, respectively. Before surgery and at 7, 15 and 30 days after surgery, the responses of rat tail to transcutaneous electrostimulation, thermal stimulation and mechanical stimulation were examined. Results: The postoperative threshold values of rats to transcutanenous electrostimulation, thermal stimulation and mechanical stimulation in the FE and NE groups were not significantly different from the preoperation (P0.05), while there were significantly differention on electrical, mechanical and thermal hyperalgesia from 7 to 30 days after surgery in the NS group (P0.05).Conclusion: Collagenase can eliminate the hyperalgesia induced by nucleus pulposus allografted into the epidural space in rats.