Pathologic Changes Of Articular Cartilage In Ovariectomied Rats

Objective-To investigate the effect of osteoporosis on tibia articular cartilage of SD rats, the relationship between estrogen and the degeneration of articular cartilage. Methods-48 eight-month old female SD rats were divided into two groups randomly, one was experiment group, underwent bilateral ovariectom, another was control group, underwent sham operation. Three month later, we got the osteoporosis model successfully. Then the rats were sacrificed at 2^th, 4^th, 8^th, 12^th week and the articular cartilages of tibia underwent formalin fixation, paraffin imbedding, The gross pathology and the immunohistochemistry of collagen I, II, III and sox9 were measured.Results- HE, toluidine blue, safranin-O and alcian blue stain show that the number of chondrocytes and cartilage thickness were similar in experiment and control group at 2^th, 4^th week. Meanwhile joint surface were smooth and tide lines were integrated. Compared with control group, cartilage thickness of experiment group became thinner (control group: 290.8±74.2μm; experiment group :95.0±20.2μm, P<0.05), and the joint surface were locally destroyed in experiment group at 8^th week. Also, tide lines are integrated and the number of chondrocytes were similar. At 12^th week, cartilage thickness were distinctly thinner in experiment group(experiment group:93.3±16.1μm, control group:270.8±48.5μm, P < 0.05 ) , the number chondrocytes increased remarkably, joint surface became rough and denudations appeared, tide lines were not integrated in experiment group. Immunohistochemistry stain show the expression of collagen II decreased sharply at 8^th and 12^th week, the expression of sox9 have no obvious change. Compared with experiment group, Mankin's grade scale of control group (experiment group :4.2±0.2, 5.0±0.3; control group: 2.5±0.2, 2.8+0.5) was significantly decreased(P<0.05)at 8^th, 12^th week.Conclusion-Osteoporosis can affect the articular cartilage structurally, the decrease of estrogen can lead to degeneration of articular cartilage in rats.