[Experimental study on lumbar intervetebral disc degeneration model with kidney deficiency by ovariectomizing].

Objective: To observe effects of removing arms and ovarian on lumbar intervertebral disc and vertebral bone mineral density (BMD) by establishing rat model of lumbar intervetebral disc degeneration (IDD) with kidney deficiency, and to explore internal mechanism of disc degeneration, relationship between disc degeneration and osteoporosis.

Methods: Thirty Sprague-Dawley female rats aged one month were randomly divided into control group, lumbar IDD group and lumbar IDD with kidney deficiency group (combined group), 10 rats in each group. Lumbar IDD group removed double arms, lumbar IDD with kidney deficiency group removed double arms after 3 months, both ovaries were removed. Vertebral bone mineral density were observed by Micro-CT scan; morphological changes were tested by safranine O-fast green staining; II, X collagen protein expression in the intervertebral disc were obsevered by immunohistochemistry; extracellular matrix gene expression were obsevered by real-time polymerase chain reaction (RT-PCR), in order to evaluate the effects of removed of forelimbs and double ovarian on degeneration and vertebral bone mineral density of intervertebral disc.

Results: Micro-CT scan showed osteoporosis in kidney deficiency group was obviously worse than other two groups; safranine O-fast green staining showed that intervertebral space became narrowed, intervertebral disc tissue degenerated obviously, chondral palte was underdeveloped in kidney deficiency group; immunohistochemistry showed that X collagen expression increased, type II collagen expression decreased in kidney deficiency group; RT-PCR showed that type II collagen expression in lumbar IDD group and kidney deficiency group was lower than control group, and had statistical meaning among three groups (P=0.000, P=0.000); Age 1 in lumbar IDD group and kidney deficiency group was lower than control group, and had statistical meaning among three groups (P=0.000, P= 0.000); while type X collagen expression was higher than control group, but no significant meaning; MMP-13 in lumbar IDD group and kidney deficiency group was higher than control group, with significant meaning compared among three groups (P= 0.000, P=0.000); aggrecanase-2 in lumbar IDD group and kidney deficiency group was higher than control group, with significant meaning compared among three groups (P=0.006, P=0.008).

Conclusion: Rats model of lumbar disc degeneration established by removed forelimbs and ovariectomized can occure "bone like"--osteoporosis, which is similar with clinical kidney lumbar disc degeneration in tissue morphology, molecular cell biology expression.