A novel rat model of lumbar disc herniation induced by puncture: accurate positioning and controllable degree of herniation.

Background: Lumbar disc herniation (LDH) is the serious stage of intervertebral disc degeneration (IDD), and the location and degree of intervertebral disc herniation are closely related to clinical symptoms and signs. However, there is currently no low-cost, high-benefit animal model to support in vivo research on LDH.

Method: Expose the rat's lumbar 5/6 intervertebral disc through the space between the psoas major and erector spine muscles, and then use different lengths of puncture needles to control the degree of herniation and different puncture angles to push the nucleus pulposus tissue backwards to the different position. Observe the protrusion of intervertebral discs through MRI. Von Frey mechanical pain test and BBB score were used to evaluate the behavior of LDH rats. H&E and SF staining were used to observe the morphological changes after intervertebral disc herniation. Immunofluorescence was used to analyze the expression of Aggrecan (ACAN), IL-1β, TNF-α, and CD31 in intervertebral disc tissue.

Results: LDH rat exhibit varying degrees of motor and sensory dysfunction. The nucleus pulposus tissue in the center of the intervertebral disc undergoes degenerative changes, with a decrease in the content of nucleus pulposus cells and proteoglycans, an increase in the expression of inflammatory factors in the protruding tissue, and neovascularization.

Conclusion: We have successfully constructed rat models of different types of intervertebral disc herniation, including disc degeneration, bulging, central herniation, and lateral herniation, using the method of puncture of intervertebral discs. This animal model is consistent with the characteristics of LDH in terms of behavior, imaging, and histopathology.