Effect Of DHA And EPA On The Pathogenesis And Mechanism Of Osteoarthritis In Rats

Osteoarthritis（OA）is the most common form of arthritis,which affects a large proportion of adult companion animals（such as horses,cats and dogs）.The disease mainly affects the hyalurontium cartilage of the knee joint,hip joint and sho ulder weight-bearing joint.With the development of the disease,the cartilage deteriorates seriously,and the joint space narrates,and the subchondral bone thickens Chondrocytes are the only cell type in articular cartilage that forms osteophytes or bone spurs with joint swelling and pain.They regulate the synthesis and homeostasis of cartilage matrix by producing enzyme growth factors and inflammatory mediators Any damage or degenerative process will disturb the steady state,results in the stagnation of cartilage cells grow from the release and activation,cartilage cells hypertrophy or aging,caused by cartilage metabolism abnormity,resulting in OA inhibition of cartilage cells hypertrophy and aging has become a potential OA treatment targets omega-3 polyunsaturated acid（EPA and DHA）for its anti-inflammatory Antioxidant effect plays a therapeutic role in cardiovascular diseases,diabetes,rheumatoid arthritis and other diseases.Based on this,this study explored the effect and mechanism of omega-3 polyunsaturated acid on hypertrophic differentiation and senescence of OA chondrocytes,so as to provide theoretical basis for clinical treatment of OA.In this study,the right hind limb of 6-month-old SD rats was transection of the anterior cruciate ligament.After the OA model was established,the rats in the experimental group were fed with DHA or EPA（300 mg/kg BW/d or 600 mg/kg BW/d）for 6 weeks.The pain behavior of the rats was detected and the knee joint of the right hind limb was collected The quadrice ps femoris muscle and plasma articular cartilage were stained with HE TB S.O to evaluate the pathological changes of articular cartilage.The expression of Col II,Col X,MMP3,MMP13,ADAMTS5,8-OHdg,Cyt.C and C-Caspase-3 in articular cartilage were detected by immunohistochemistry.The concentrations of PGE₂ COX2 MDA and GSH in muscle were detected.In vitro cultured chondrocytes with concentrations of COMP and CTX II in plasma were detected,and cell senility model was established.After treatment with DHA（10μM）or EPA（8μM）,the secretion phenotypes of chondrocytes and antioxidant stress regulators were detected.The results of in vivo experiments showed that:（1）dietary supplementation of DHA or EPA reduced the pain behavior of OA rats;（2）The addition of DHA or EPA in the diet reduced the hypertrophic differentiation of chondrocytes in the articular cartilage of female OA rats;（3）Adding DHA or EPA to the diet could inhibit DNA damage in chondrocytes of OA rats;（4）Adding DHA or EPA to the diet can inhibit the apoptosis of chondrocytes in female OA rats.In vitro experiments showed that:（1）Both EPA and DHA can inhibit the aging of chondrocytes induced by H₂O₂;（2）DHA can inhibit the secretion of ROS by senile chondrocytes,while EPA and DHA can inhibit the secretion of MDA by senile chondrocytes.（3）DHA promoted the secretion of GSH catalase（CAT）and superoxide dismutase（SOD）in senescent chondrocytes,and EPA promoted the secretion of CAT in senescent chondrocytes;（4）EPA and DHA could inhibit the expression of p-p53 P21 in senile chondrocytes and promote the expression of SIRT1 in senile chondrocytes.（5）DHA and DPA could inhibit the expression of COL X protein and m RNA of MMP3,MMP13,Runt-related transcription factor 2（Runx2）,and promote the expression of SOX9 and COL II protein and m RNA in senile chondrocytes.These results indicate that:（1）dietary supplementation of DHA or EPA can alleviate knee joint and quadriceps femoris pain in rats induced by OA,but there are gender differences in pa in relief effect.The effects of DHA and EPA on peripheral and central pain in female OA rats need to be further studied.（2）DHA and EPA may regulate insulin sensitivity by inhibiting the lipid peroxidation of quadriceps femoris muscle,thus alleviating t he pain caused by OA.The effects of DHA and EPA on the function of quadricorn in OA rats still need to be further studied.（3）DHA and EPA have strong inhibitory effects on the hypertrophy,senescence and apoptosis of articular chondrocytes in female OA rats.Further study is needed on the effect of gender of rats on the effect of DHA and EPA.（4）In vitro experiments showed that DHA and EPA could regulate the secretion phenotype of chondrocytes through Runx2 and Sox9.（5）DHA can promote the expression of SIRTI and inhibit the expression of p53 in cultured senile chondrocytes.However,the signaling pathways of DHA inhibiting soft cell senescence and hypertrophic differentiation still need to be further studied.