| Objectibe: To investigate the protective effects on the articular cartilage in ovariectomized rats with the decrease of the estrogen and the effects of exogenous estrogen,soy isoflavone on the the articular cartilage and subchondral bone In vivo. Methods: 120 female, 3-month-old Wistar rats were randomly divided into 6 groups:sham(sham-operation),OVX(ovariectomy),DES(OVX+diaethylstilbestrol),L-SI(OVX+low dose soy isoflavone ),M-SI(OVX+moderate dose soy isoflavone ) ,H-SI(OVX+high dose soy isoflavone ) (n=5 in a group).Establishment of the model:OVX rats model was established by resecting bilateralis ovaries.Administration and doses:administration by gavage.once daily, 16-week period continuous;the rats in sham group and OVX were given one millilitre of distilled water by gavage equal volum,the rats in DES group were given 0.86mg/kg/d diaethylstilbestrol dissolved in 1 ml distilled water by gavage, the rats in L-SI group were given 30mg/kg/d soy isoflavone dissolved in 1 ml distilled water by gavage.the rats in M-SI group were given 60mg/kg/d soy isoflavone dissolved in 1 ml distilled water by gavage,the rats in H-SI group were given 120mg/kg/d soy isoflavone dissolved in 1 ml distilled water by gavage,respectively. Sacrifice time,drawing the materials and measurement indexs:At 4-week,8-week, 12-week, 16-week after administration,randomly killing 5 rats in every group.The body weight of rats killed was weighted.the blood samples were collected from femoral artery before they were killed,isolating serum after centrifugalization and serum was taken for determination of serum estrodiol(E2) by radioimmunoassay.The uteri removed and weighed,calculating coefficient of uteri;fixed uteri,paraffin imbedding,makingsections,rout HE stain for pathologic observation.Taking integrated knee joint(including femur and tibia about 0.8cm),decalcification in 10% EDTA liquid,paraffin imbedding and making samples into sections,then HE stain,toluidine blue stain,safranin O stain,estrogen acceptor P immunohistochemistry stain for pathologic observation of articular cartilage.Determining thickness of articular cartilage and subchondral bone,MOD value of articular cartilage(MOD is mean optical density,can reflect content or concentration of proteoglycan in cartilage matrix) using pathologic image analysis system. All measurement data was statistical treatment by SPSS10.0.Results: 1 .The coefficient of uteri and concentration of serum E2 in the OVX group were significantly lower than that in the sham group(P<0.05);Thickness of articular cartilage,MOD value of articular cartilage and thickness of subchondral bone in the OVX group were significantly lower than that in the sham group(/><0.01).2.The coefficient of uteri and concentration of serum E2 in L-SI,M-SI,H-SI were significantly higher than that in the sham group(/><0.01),lower than in the DES(P < 0.05,P < 0.01).Thickness of articular cartilage comparisons:about articular cartilage of femur.thickness of articular cartilage of L-SI,M-SI,H-SI in 16-week is 143.35±8.50um,150.33±7.75um,155.29±5.50um respectively.Significantly higher than the thickness(118.24±11.95um) in the sham group,is not significant deviation with the DES(147.95±8.57um).about articular cartilage of tibia,thickness of articular cartilage of M-SI in 8-week, 12-week is 334.50±21.30um,355.54±23.57um respectively,that of the DES is330.76±7.08um,334.60±43.53um,not significant deviation.thickness of articular cartilage of H-SI in 4-week is 313.46±37.85um,is284.92±4.47um,that is significantly lower than that in DES,L-SI,M-SI.MOD value of articular cartilage comparisons:about articular cartilage of femur,MOD value of L-SI,M-SI and H-SI is significantly higher than the sham group(P<0.01).MOD value of H-SI in 4-week,8-week, 12-week, 16-week is significantly higher than the DES(P<0.01),but MOD value of L-SI and M-SI is lowe than the DES(P< 0.01).about articular cartilage of tibia,MOD value of H-SI in 4-week,8-week, 12-week, 16-week is near DES or higher than DES.MOD value of L-SI and M-SI is higher than the OVX group(P<0.01),but is lower than H-SLL-SI and M-SI is not significant deviation.Thickness of subchondral bone comparisonsrabout subchondral bone of femur articular cartilage, the highest value of H-SI is 40.8565±3.0166um,the highest value of DES is only 33.2098 + 4.7235um,thickness of H-SI is significantly higher than DES(P < 0.05,P < 0.01);thickness of L-SI and M-SI is significantly higher than OVX(P<0.01),but not significant deviation with DES.about subchondral bone of tibia articular cartilage.the highest value of H-SI is 37.4449±3.3226um,the highest value of DES is only 38.5791±2.8778um,both them not significant deviation,further is higher than L-SI and M-SI. Immunohistochemistry staining show estrogen acceptor Ppositive in chondrocyte of articular cartilage.Conclusion: 1 .Confirming articular cartilage appear morphologic degeneration and content of proteoglycan decreasing in ovariectomized rats with the decrease of the estrogen,this may be important etiopathogenisis of post-menopause women osteoaithritis;2.Mechanism of articular cartilage degeneration in ovariectomized rats may be estrogen acceptor pathway;3.Exogenous estrogen has the protective effectson the articular cartilage in ovariectomized rats;4.Soy isoflavone may delay articular cartilage degeneration,be phytoestrogen effect;5.Need sequence approach the mechanism that different changes in different part of articular cartilage,relation of between articular cartilage and subchondral bone.
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