Establishment of new rat model for sciatica induced by lumbar disc her-niation and new method for epidural catheterization

Objective: To establish new rat model for sciatica induced by lumbar disc herniation and new method for epidural catheterization.Methods: 60 male SD rats were randomly divided into model group(n = 36),sham group(n = 12) and blank group(n = 12).Autologous nucleus pulposus was applied to the L5 dorsal root ganglion(DRG) and epidural space and PE-0503 catheter was put into epidural space in model group.Autologous nucleus pulposus was harvested but not applied to the L5 DRG or epidural space in sham group.There was nothing operation in blank group.General behaviors were observed and 50% paw withdrawal threshold(50%PWT) was measured 1 day before the surgery and on days 1,3,7,14,21,and 28 after surgery in each group with 6 rats.On day 7 after surgery,the left L5 DRGs were obtained for detecting the expression of NOS and COX-2 in each group with 6 rats.On days 2,6,13 and 20 after surgery in model group(6 rats each day),rats were dissected to evaluate the position of the catheter tips and the extention of drug in epidural space.Results: No motor,urination and defecation disfunction were observed.50%PWT after surgery were significantly lower than 1 day before surgery,blank group and sham group(P 0.05).Significant increase of positive cell numbers of NOS and COX-2 was observed in model group(P 0.05).The catheter tips were all at epidural space and the extention of durg in epidural space after day 6 was stable(P 0.05).Conclusion: This new rat model for sciatica induced by lumbar disc herniation was reliable with stable mechanical hyperalgesia and assured inflammatory response,and the epidural catheterization was proved to be feasible.