| Purpose: Tendon injuries are one of the common sports injuries.Recent researches have shown that females are more times greater to tendon injuries than males,especially females with higher concentrations of serum relaxin.Relaxin is a peptide hormone secreted by the corpus luteum of the ovary,which affects the metabolism of extracellular matrices,including collagen,hyaluronic acid,and polysaccharides.At present,the effect of relaxin on tendon and the effect after injury is still slightly elucidated.This research aims to study the effect of relaxin on collagen metabolism of tendon stem cells and the healing of rat tendon ligament injury,so as to prevent female tendon ligament injury.Methods: In vitro experiments,we performed on rat tendon stem cells(TSCs)by different concentrations of relaxin(0,1,10,100 ng/ml).Collagen metabolism and related matrix metalloproteinase were observed by Rt-PCR.Then,we performed Western blot to analyze the signal pathways.In vivo experiments,we performed a rat patellar ligament injury model,and saline(0.2 ?g/kg/day)and relaxin(0.2 ?g/kg/day)were injected locally.After 2 and 4 weeks,the rats were sacrificed and bilateral sputum was taken.The ligaments were analyzed by biomechanics,histology and immunohistochemistry staining.Results: In vitro,relaxin can increase the expression of MMP9,13 by activating AKTERK1/2 signaling pathway,and thus less synthesis of Col-1 and Col-3.In vivo,local injection of relaxin reduced the ultimate tensile force,stiffness and Young's modulus after healing of the patellar ligament.Histological results suggest that local injection of relaxin increased the expression of relaxin receptor 1(RXFP1)and changes the balance between matrix metalloproteinase 9,13(MMP9,13)and matrix metalloproteinase inhibitor-1(TIMP1).Lead to a reduction in collagen deposition.Conclusions: Relaxin impairs tendon healing in rats.Meanwhile,relaxin might lead to tendon injury more commonly for females than males. |
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