BACKGROUND:Intervertebral disc degeneration is an important cause of low back pain.At present,there are many modeling methods for disc degeneration in China and abroad,but there is not a model for low back pain due to disc degeneration. OBJECTIVE:To compare the effect of mechanical puncture combined with tumor necrosis factor α and complete Freund's adjuvant with a conventional disc mechanical puncture alone. METHODS:A total of 18 male adult Sprague-Dawley rats were randomly divided into 3 groups,with 6 animals in each group.No treatment was given in the blank group.Animal models of intervertebral disc degeneration were made in the L4-5 segments of rats in the control using conventional mechanical puncture.In the experimental group,on the basis of mechanical puncture,tumor necrosis factor α+complete Freund's adjuvant was injected into the L4-5 intervertebral discs using a microinjector to establish a model of disc degeneration induced by mechanical puncture combined with inflammatory factors.Four weeks after surgery,the pain threshold of rats was measured by the hot plate method for assessing the perception of heat injury in rats with intervertebral disc degeneration.MRI examination was performed to observe the disc degeneration in each group.ELISA was used to detect the levels of serum tumor necrosis factor α,interleukin 1β,interleukin 6 and prostaglandin E2.Hematoxylin-eosin and Safranin O-fast green staining were used to observe the morphological changes of the disc. RESULTS AND CONCLUSION:In terms of pain,the behavioral pain threshold of the experimental group was continuously decreased,and the levels of serum inflammatory factors were significantly higher compared with the control group.In terms of morphology,the MRI results showed that the L4-5 nucleus pulposus signal completely disappeared in the experimental group.Histopathological results showed that in the control group,the nucleus pulposus was intact,more notochord cells were visible,and some fiber rings were ruptured,while in the experimental group,there are fewer notochord cells and the structure of the nucleus pulposus and fibrous ring is disturbed,with the boundary disappearing.To conclude,mechanical puncture combined with tumor necrosis factor alpha and complete Freund's adjuvant can successfully establish a discogenic low back pain model in rats.This operation is simple and economical to achieve obvious disc degeneration and low back pain,with greatly shortened molding cycle.This model can be used as a reference for studying discogenic low back pain models.