The Effect Of Doxycycline Inhibiting The Matrix Metalloproteinase In The Intervertebral Disc Degeneration Of Rats

PrefaceIntervertebral disc degeneration (IDD) has been linked, both directly and indirectly, to an epidemic of low back pain. Furthermore, it is high morbidity induce that depressing the quality of life in middle-aged adults. A better understanding of the pathogenesis of intervertebral disc degeneration will be the consequence contributed by biological and biomechanical factors in most researchers. At present the research hopes to develop strategies to treat and prevent disc degeneration using biologically active molecules which can promote disc matrix anabolic and/or inhibit the activity of matrix catabolic enzymes. Doxycycline belongs to the telracycline family. It can inhibit the mRNA expression of matrix metalloproteinase (MMPs), the key enzyme of Intervertebral disc degeneration, and combinate enzymic active spot to inhibit its activity directly. Clinically, Doxycycline has been used to treat abdominal aneurysm, ischemical reperfusion injury and rheumatoid arthritis, but do not in the Intervertebral disc degeneration. Our goal in this study is to investgate the activity of MMP-3 and MMP-13 in the degenerative disc after injecting Doxycycline.Methods1. The source of animal60 Adult SD rats of pure breed are collected, no female or male limited, which are provided and raised by China Medical University. 2. Disc Degeneration Model constructionTo identify the 10th coccygeal disc of rats, Kirschner pins were inserted percutaneously through adjacent vertebral bodies using a small drill. Two pins were inserted perpendicularly in each vertebral body. A calibrated, elastic loop cut from silicone tubing was then placed around each of the four opposing ends of the pins to compress the disc at 1.3 MPa stress. The rat was afforded free range of motion while the loading device was in place. The discs were loaded for 7 days, and then the load released by cutting the elastics. Then injection treatment with Doxycycline and saline was begun. The rats were sacrificed at both the 7th day and the 14th day after operation.3. HE staining and Western blot testInvestigate the disc degeneration with HE staining at the 7th day after operation. To investigate the expression of MMP-3 and MMP-13 with Western blot test at the 14th day after operation.Results1. Results of HE stainingAt the 7th day after operation, nucleus pulposus cell and extracellular matrix decreased. Parts of nucleus pulposus cell occured apoptosis. Fragmentation and reductus were found in some of annular fibrosus. Cartilage excavation enlarged in the end plate.2. Results of Western blot testAt the 14th day after operation, the expression of MMP-3 and MMP-13 in saline group was significantly high compared with Doxycycline group (P<0.05) .Discussion1. Disc degeneration model construction It is confirmed in the result of HE staining that the goal of making disc degeneration model had been achieved through the tail of rats with static loading. This is a good model for research the treatment of intervertebral disc degeneration.2. Results analysis of Western blot testIn the disc with injecting Doxycycline, the expression of MMP-3 and MMP-13 decreased significantly compared with saline group. It is indicated that at the physiological condition of the disc degeneration Doxycycline can inhibit the expression of MMPs. Because the MMPs are key enzyme of matrix catabolism, Doxycycline will play a important role in the catabolism of disc degeneration.ConclusionDoxycycline can inhibit the expression of MMPs in the intervertebral disc degeneration, which indicat Doxycycline can inhibit the disc degeneration in partly degree.