[Protecting effect of Quan Duzhong Capsule() on the cartilaginous endplate so as to improve acupuncture-induced intervertebral disc degeneration].

Objective: To investigate the protective effect and underlying mechanism of Quan Duzhong Capsule () on acupuncture-induced caudal intervertebral disc degeneration in rats.

Methods: Sixty male Sprague-Dawley rats were weight-stratified and randomly divided into 6 groups (10 rats per group). A 26 G needle was used to puncture the rat coccygeal vertebrae to establish an intervertebral disc degeneration model, while the control group only received acupuncture on the skin lateral to the coccygeal vertebrae. The model groups received either Quan Duzhong Capsule () at a dose of 300 mg·kg-1 or normal saline via intragastric administration. Samples were collected at 4 and 8 weeks post-modeling, respectively. Longitudinal assessment included weekly 3.0 T MRI scans to dynamically evaluate changes in the nucleus pulposus, with measurements of the nucleus pulposus height, area, signal value, and the disc height index(DHI). Isolated coccygeal segments underwent micro-computed tomography (Micro-CT) to analyze the morphological changes in the vertebrae at both ends of the modeled intervertebral discs, and bone microstructure parameters were analyzed. Coccygeal vertebral tissues were decalcified and embedded in paraffin. Hematoxylin-eosin (HE) staining and Toluidine Blue staining were used to assess the tissue morphology and cartilage damage. Immunohistochemistry was performed to analyze the expression of aggrecan (Acan) and typeⅡcollagen(ColⅡ). Total mRNA was extracted from the nucleus pulposus, and quantitative reverse transcription polymerase chain reaction(qRT-PCR) was used to detect the gene expression of Acan and ColⅡ.

Results: MRI scan results showed that compared with the control group, the nucleus pulposus signal at the injured site in the model group gradually disappeared with the increase of time after acupuncture modeling, indicating the successful establishment of the acupuncture-induced caudal intervertebral disc degeneration model. Dynamic MRI acquisition data revealed that the T2WI signal value, height, area, and DHI of the nucleus pulposus in rats of the Quan Duzhong Capsule() administration group were significantly higher than those in the model group(P<0.05). Micro-CT analysis results demonstrated that after 8 weeks of Quan Duzhong Capsule() treatment, the bone volume of the vertebrae adjacent to the nucleus pulposus injury site and the trabecular bone thickness were significantly increased compared with the model group (P<0.05), while the bone surface area to bone volume ratio, structural model index, trabecular separation, and pattern factor were significantly decreased (P<0.05). Histological staining results indicated that compared with the model group, the intervertebral disc tissue morphology in Quan Duzhong Capsule () administration group was relatively intact;Toluidine blue staining showed that the chondrocyte layer in Quan Duzhong Capsule () administration group was thicker than that in the model group; immunohistochemistry results revealed that the expressions of Acan and ColⅡ in the acupuncture-induced intervertebral discs of rats in Quan Duzhong Capsule () administration group were significantly higher than those in model group(P<0.05). qRT-PCR results showed that after 8 weeks of Quan Duzhong Capsule() treatment, the mRNA expressions of Acan and ColⅡ were upregulated by 1.5 and 1.6 times, respectively, compared with the model group(P<0.05).

Conclusion: Quan Duzhong Capsule () can alleviate acupuncture-induced caudal intervertebral disc degeneration in rats and inhibit the reduction of extracellular matrix in the intervertebral disc during the degeneration process.