The Effect Of Estrogen On The Post-traumatic Osteoarthritis Of The Knee Joint Of Mice

Objective:To investigate the effect of estrogen on the progression of post-traumatic osteoarthritis in mice.Methods:64(female=48,male=16)of 12-week-old ICR mice,female mice were randomly divided into group A(female control group),group B(ovarian group),group C(Ovarian supplementation of estrogen group)and group D(male group),16 in each group.All mice underwent medial meniscus instability surgery on the right knee and Sham surgery on the left knee,group B mice underwent bilateral ovariectomy,and Mice in group C underwent subcutaneous embedding with estrogen tablets(0.72 mg / 90d)at the same time.All the weights were measured every 4 weeks after operation.Half of the mice in each group were randomly sacrificed at 8 and 12 weeks after surgery,heart blood collection to determine serum estrogen levels in mice,The bilateral knee joint tissues were collected,4% paraformaldehyde fixation for 24?48 hours,10% EDTA decalcified for 4 weeks,paraffin embedded,5 ?m continuous sections,saffron O-fast green staining,to observe the morphological changes of articular cartilage,evaluate the degree of articular cartilage lesions by analyzing the results of Mankin score,articular cartilage thickness and area,tissue sections were treated with MMP13,P-EGFR immunohistochemistry and chondrocyte apoptosis fluorescent staining at 12 weeks after surgery.SPSS 18.0 statistical software was used to analyze the data.P <0.05 indicated that the difference was statistically significant.Results:1.The weight of group B mice was significantly higher than that of group A and C mice(P <0.05).2.The serum estrogen level in group A was significantly higher than that in group D during the same period(P <0.01).Compared with group A,the estrogen level of mice in group B was significantly decreased after castration(P <0.01),while the serum estrogenlevel of group C mice was significantly higher than that of group B micein the same period(P <0.01).3.In the same period,the cartilage damage of the knee joints in the DMM side of the mice in the A group was significantly greater than that in the Sham side,with Mankin scores of [(5.87 � 0.99)points:(0.38 � 0.52)points,(7.12 � 0.84)points: 0.63 � 0.52)points] and The comparison of cartilage thickness was statistically significant(P <0.01).4.Compared with group A and group C,the degree of cartilage damage of knee joints in Sham side was more severe the mice in group B in the same period.The differences in Mankin score,cartilage area and thickness were statistically significant(P <0.05).DMM side knee The joints showed similar results,but the degree of cartilage damage was significantly greater than that of the Sham side knee joint.There was no significant pathological change in the cartilage of the knee joints in the Sham side of the mice in group D,while the degree of cartilage damage in the knee joints of the DMM side was more severe than that the mice in the group A,Mankin score [(7.88 � 1.13)points:(5.87 � 0.99)points] at 8 weeks after operation(P <0.05),the lesions were further exacerbated at 12 weeks after operation,and the Mankin score was [(10.25 � 1.04)points:(7.12 � 0.84)points](P <0.01).5.Compared with the Sham side,the expression of MMP13 in knee cartilage on the DMM side was significantly higher(P <0.01).Compared with group A,the expression of MMP13 in the knee cartilage of DMM side was higher(P <0.01),but there was no statistical difference in Sham knee cartilage(P>0.05).Compared with group A,the expression of MMP13 in ipsilateral knee cartilage of mice in group B was significantly increased after castration(P <0.01).Compared with group B,the expression of MMP13 in ipsilateral knee cartilage of group C mice was significantly decreased(P <0.01).6.Compared with the Sham side,the proportion of apoptotic chondrocytes in the knee joints of mice in the DMM side was higher(P <0.01).Compared with group A,the proportion of apoptotic chondrocytes in the knee of DMM was higher in group D(P<0.01),but there was no significant difference in the comparison of Sham side knee cartilage(P>0.05).Compared with group A,the proportion of apoptotic kneechondrocytes on the ipsilateral knee joint was higher in group B after castration(P<0.01),compared with group B,the percentage of chondrocyte apoptosis on the ipsilateral knee joint of mice in group C was significantly lower(P <0.01).7.Female mice had higher expression of P-EGFR in DMM than in Sham knee cartilage(P <0.01).Compared with group A,the expression of P-EGFR in ipsilateral knee cartilage of group B mice was significantly higher after castration(P <0.01).The expression of P-EGFR in ipsilateral knee cartilage of group C mice was significantly lower than that in group B(P <0.01).Conclusion:1.Regulating effect of estrogen on PTOA,estrogen deficiency leads to aggravation of PTOA,and supplemental treatment can inhibit cartilage damage and delay the progression of PTOA.2.Estrogen can protect articular cartilage by inhibiting the expression of MMP13 in articular cartilage and reducing the apoptosis of chondrocytes.3.Estrogen can inhibit the activation expression of EGFR signaling pathway in articular cartilage,and then inhibit excessive damage of articular cartilage.