Feasibility Of Using Ovariectomy To Establish An Animal Model Of Osteoarthritis

BackgroundOsteoarthritis(OA), characterized by progressive joint cartilage degeneration、subchondral bone exposed and secondary synovitis,is a type of degenerative joint diseases,and is particularly common in the elderly.Epidemiological studies show that the male incidence of OA is slightly higher than women before the age of 50;the incidence of female is significantly higher than male after the age of 50.A large number of studies show that postmenopausal women losing the protection of estrogen as well as the abnormal level of joint inflammatory cytokines together play an important role in the onset of OA. Additionally, estrogen replacement therapy(ERT) for the relief of OA symptoms shows certain effect, which also indicate a probable correlation between estrogen and incidence of OA after menopause.Osteoporosis(OP)is a type of retrogressive bone metabolic disease,characterized by lower bone mass compared with normal 、 declination of bone strength and increased brittleness. Its main manifestation is the increasing bone fragility due to systemic osteopenia and disorganized bone microstructure, which is more prone to fracture. Itsetiology is also quite complex, while the same as OA, OP is also popular in postmenopausal women and elderly.Objective1. To verify whether OVX, which is regarding as abarticular intervention, can be used to construct an animal model of OA.2. After establishment of the model, extract and culture chondrocytes from OA, combine with the intervention of estrogen, and detect the levels of three inflammatory related factor which are MMP-3、MMP-13、ADAMTS-5 with the observation of the effect of estrogen in the process.Methods1. Selecting 6 months old female SD rats to carry through bilateral ovariectomy, so as to establish an OA animal model.2. Using microscope observation, system scoring, and histological observation of joint tissue by the method of HE staining and red solid green dyeing, to evaluate the quality of the model.3. With the extraction OA chondrocytes in model animals and articular cartilage cells in normal female rat by the method of two-steps enzyme procedures, treat the OA chondrocytes with estrogen, then detect relative expression of MMP-3 、 MMP-13 、ADAMTS-5 gene by real-time fluorescent quantitative PCR.4. Detect the secretion and expression of MMP-3、MMP-13、ADAMTS-5 molecules in the three groups of chondrocytes by means of Western blot.Results1. The degree of articular cartilage lesions can meet the diagnostic criteria of OA by establishing the OA animal model by OVX.2. Extract articular chondrocytes and conduct primitive culture, transfering after culture and purification, then detect the expression of MMP-3、MMP-13、ADAMTS-5 gene in OA chondrocytes by real-time fluorescent quantitative PCR. The results show that MMP-3expression is significantly increased, compared with the control group(P < 0.05); The expression of MMP-13 and ADAMTS-5 is in downward trend, compared with the controlgroup(P < 0.05).3. Western blot shows that the secretion and expression trend of MMP-3、MMP-13、ADAMTS-5 in OA chondrocytes is consistent with the above results.4. After treatment of estrogen in OA culture solution, the expression levels of MMP-3 and MMP-13 in OA chondrocytes are changed to meet the tend of normal chondrocytes.Conclusion1. OVX can be used to establish an OA animal model by means of simulating natural occurrence of OA in postmenopausal women.2. Compared with the normal articular cartilage cells, the expression of MMP-3 is obviously increased in OA chondrocytes, suggesting that it is positively correlated with the occurrence of OA, which is consistent to results reported in studies; and the expression levels of MMP-13, ADAMTS-5 are reduced, which is different in molecule expression levels from animal models that rely on the change of stress around joints, suggesting that they are different from OA animal models establishing by OVX in occurrence mechanism.3. In cellular level, estrogen can reverse the expression levels of MMP-3 and MMP-13 in OA chondrocytes to some extent, suggesting that estrogen plays a therapeutical effect in OA articular cartilage cells.