| Background and objective:lumbocrural pain is common diseases in clinic. About eighty-percent of people undergo lumbocrural pain in their lives. At present most of studies indicate that lumbar intervertebral disc degeneration play a important role in lumbocrural pain. But the reason that lead to cartilaginous endplate degeneration and apoptosis remain unclear. We establish an animal model of lumbar intervertebral disc degeneration to study the relationship between cartilaginous endplate apoptosis and lumbar intervertebral disc degeneration caused by destabilization in rats determining the effect of apoptosis in intervertebral disc degeneration to provide the new methods for preventing and curing lumbar intervertebral disc degeneration.Methods:24 rats were divided into two groups randomly,12rats as the experimental model group and the other 12 ones as the control group. The experimental model group was established by resection all supraspinous and interspinous ligaments, excision of paravertebral muscles of the spine, accelerating disc degeneration. The control group was incised only the skin. At each time period of 9 weeks,18 weeks and 36 weeks after surgery, rats were killed by over anesthesia to get all the intervertebral disc tissue completely. The samples were cut in midsagittal direction. To separate the disc and cartilaginous endplate. Lumbar intervertebral discs were evaluated according to Thompson criterion. Endplate sections were stained with Tunel procedure. The number of apoptotic cells and vital cells were counted, the degree of degeneration were evaluated.Results:1. Histologic evaluation of lumbar intervertebral disc degeneration.The degree of lumbar intervertebral disc degeneration was evaluated by use of the hematoxylin and eosin stained sections. The rats intervertebral disc of the 9 weeks control group and experimental model group are normal mainly. The rats intervertebral discs of the 18 weeks control group degenerated gently. Cartilaginous tissue of anterior part of annular fibrosus hyperplasied. The sequence is not normal, nucleus pulposus deviated to posterior. The edge of vertebral is smooth. The rats lumbar intervertebral discs of the 18 weeks experimental model group degenerated more obviously than that of 18 weeks control group. The parts of annular fibrosus are fibrotic. The boundary between annular fibrosus and nucleus pulposus is too blurred. In posterior of vertebrate, the osteophyma formed.The rats lumbar intervertebral discs of the 36 weeks experimental model group degenerated seriously.The annular fibrosus are fibrotic tatally. Nucleus pulposus disappeared. The osteophyma formed obviously in posterior of vertebrate.2. To observe the lumbar intervertebral cartilaginous endplate by HE stained.The degeneration of the structure of the lumbar intervertebral cartilaginous endplate accelerated while the rats become olderer and older. The lumbar intervertebral cartilaginous endplate of the rats of 9 weeks control group and experimental model group is thick. We can see some cartilage lacuna. The cartilaginous endplate instructure of 18 weeks control group and experimental model group all disappeared partly. We can see some apoptotic body. Cartilaginous endplate of 36 weeks experimental model group disappeard obviously.3. To compare apoptosis rate between two groups by Tunnel stained.We can see few apoptosis cells in two groups of 9 weeks. We can see a few apoptosis cells in two groups of 18 weeks. But apoptosis cells have difference between two groups. In 36 weeks,there have large difference between two groups. Experimental model group has more apoptosis cells than contal group.Conlcusions:1. The lumbar intervertebral degeneration animal model accelerated lumbar intervertebral discs degeneration and increased the quantities of apoptosis cells of endplate chondrocytes.2. Apoptosis of endplate chondrocytes is one of the most important reasons to lumbar intervertebral discs degeneration.
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