Abstract:

BACKGROUND: Estrogen deficiency can result in a series of physical or chemical changes in intervertebral disc. Studies have demonstrated that matrix metalloproteinase-3 (MMP-3) can degrade proteoglycan poly and ground substance of intervertebral disc. Interleukin-20 (IL-20) also plays an important part in intervertebral disc degeneration.
OBJECTIVE: To explore the effect of estrogen on IL-20 and MMP-3 expression in lumbar nucleus gelatinosus of ovariectomized rabbits.
METHODS: New Zealand white rabbits were randomly divided into the normal control, model, low-dose estrogen and high-dose estrogen groups. All rabbits were prepared for ovariectomized models except that of the normal control group. Sodium chloride  (2 mL), estradiol benzoate (0.2 mg or 1 mg) were intramuscular injected into animals in the normal control, low- and high-dose estrogen groups every other day, respectively. The lumbar nucleus was harvested at 3 months after operation. The expression of IL-20 and MMP-3 was tested by hematoxylin-eosin staining, immumohistochemistry and Western-blot.
RESULTS AND CONCLUSION: The cell density and notochord cells were obviously decreased in the model group, with agglomerate notochord-like cells. There were no marked changes in the other groups. The immumohistochemistry results demonstrated that, the positive expression of IL-20 and MMP-3 in the model group was greater that of the normal control and high-dose estrogen group (P < 0.05). Western-blot exhibited similar results as immumohistochemistry. The results demonstrated that intramuscular injection of estrogen can decrease expression of IL-20 and MMP-3 in degenerated lumbar nucleus, thereby, prevent degradation of nucleus pulposus.