Investigation of the mechanism of intervertebral

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In this research, we investigated the cause of degeneration intervertebral disc (IVD) and the mechanism of IVD herniation in dogs by means of magnetic resonance imaging (MRI) in Yamaguchi University Hospita. We divided two study groups in which were chondrodystrophoid (CHD) breed, such as dachshund or beagle, and non-chondrodystrophoid (NCHD) breed, such as maltese. In IVD of CHD breed, the signal intensity of T2-weighted image was higher than that of NCHD. This was suggested that there were more moistly in IVD of CHD than that of NCHD because there were chondrocyte in the nucleus pulposus in CHD and not in NCHD. Then we investigated the biochemical activity of several cystein proteinases in the nucleus pulposus (NP), which was center of IVD, and anulus fibrosus (AF), which was surround of NP, by means of biochemical analysis. In IVD of beagle dog which was CHD group, there were much more cathepsin L than cathepsin B, which both proteinase were a member of cystein proteinase family. And proteinase activity was higher at NP than AF in each proteinases. These results suggested that the mechanism of IVD degeneration and/or herniation was related to region specificity or pH specificity because of cathepsin L activity was higher at acidic region. This may be important key to investigate the cause of IVD degenetation and herniation in dogs.