Mechanism Of Autophagy In Femoral Head Necrosis Induced By Glucocorticoid In Broilers

Femoral head necrosis(FHN)is one of the most common leg diseases in fast-growing broilers.FHN-affected broilers are unable to walk normally,difficulty eat and drink,stunt growth and significantly reduce production performance,ultimately causing biggish economic losses.The pathogenesis and meachaism of FHN remain to be further studied.The function of articular cartilage is directly related to chondrocytes’ viability and surivial.In this study,two different kinds of glucocorticoid(GC),methylprednisolone(MP)and dexamethasone(DEX),were treated via examining the expressions of autophagy-related genes and comparing the indicators,the mechanism of autophagy of articular chondrocytes in FHN-affected broiler was explored.In the experiment,GCs were used to treat chondrocytes of broilers to further clarify the mechanisms involved in autophagy.Experiment Ⅰ Production Performance and Bone Metabolic Parameters of Femoral Head Necrosis Induced by Two Glucocorticoids in BroilersIn this study,we investigated two GC-induced FHN mechanisms in broiler.1 d broilers were ramdomly divided into CON,MP or DEX group.Broilers in three groups were injected with different reagents.Blood and bone samples were collected to evaluate blood lipid metabolism levels,bone metabolism levels,bone parameters,morphological changes of cartilage,and expressions of articular chondrocyte autophagy-related genes,in order to determine changes in bone physiological parameters,bone metabolic markers and chondrocyte autophagy.The results showed that GC treatment significantly decreased the levels of bone parameters,significantly changed expressions of cell secreted products related and autophagy-related genes compared with CON group.The results also showed that GC treatment significantly affected growth,bone and blood lipid metabolismin levels in broilers.Thence,it suggested that chondrocytes autophagy occurred in broilers during GC-induced FHN,and provided further data for the pathogenesis of GC-induced FHN.Experiment Ⅱ Mchanism of Articular Cartilage Damage Caused by Autophagy in Femoral Head Necrosis Induced by Methylprednisolone in BroilersIn this study,the influence of MP and 3-MA on chondrocyte autophagy and bone quality were determined to investigate the mechanisms of femoral head necrosis in broilers.Broilers were divided into four groups:CON,MP,3-MA,and 3-MA+MP groups.Broilers in different groups were injected with different reagents.Blood and bone samples were collected for laboratory examination.The results indicated that MP treatment significantly affected the levels of serum lipid and bone metabolism in broilers.MP treatment also significantly reduced the levels of bone parameters compared with control group.MP treatment inhibited the expressions of collagen-2,aggrecan and mTOR.MP treatment increased the expressions of beclinl,LC3,HIF1α,HIF2α,PI3K,AKT and ATG5 of the femoral head articular cartilage.Co-treatment with 3-MA mitigated MP-induced effects on parameters.Thus,autophagy was involved in the pathogenesis of FHN induced by MP in broilers,and 3-MA had inhibitory influences on chondrocyte autophagy in FHN-affected broilers.Experiment Ⅲ Autophagy Mechanism of Articular Chondrocytes Induced by MethylprednisoloneThis study was designed to investigate the effects of methylprednisolone(MP)on articular chondrocyte autophagy.Isolation and culture of articular chondrocytes provide a simple and feasible cell culture method for further study of broiler chondrocytes.The culture medium supplemented with 10%FBS was used for the culture of broiler articular chondrocytes.The articular chondrocytes were identified via toluidine blue,alcian blue staining,and PCR amplification respectively.Articular chondrocytes were treated with 0.1μmol/L MP,0.1 μmol/L MP and 5 mmol/L 3-MA,and 50 MOI HIF-1α overexpressed lentivirus.The results showed that MP decreased cell viability and significantly promoted the expressions of autophagy genes in chondrocytes.Otherwise,3-MA had a protective effect on MP-induced autophagy in articular chondrocytes.This method provides feasible steps for the separation of articular chondrocytes in broilersand a new basis for prevention of FHN induced by GC in vitro.