Study On The Effect And Mechanism Of Calcium-sensitive Receptors In Cooperation With Parathyroid Hormone In Promoting Fracture Healing

In order to study the role and mechanism of the calcium sensing receptor(CaSR)-mediated parathyroid hormone(PTH)to accelerate fracture healing,we established a mouse model of the control group(wild-type and double knockout)and experimental mice models(wild-type and double knockout).We take the 8-week-old littermates.Femoral fracture model modeling side,the other side of the femur as a control,using the drawn,X-ray radiography,immunohistochemical methods analysisand femur bone callus characteristics four weeks after.Experimental group was given a daily subcutaneous injection of exogenous PTH(1-34),80?g/kg body weight for 4 weeks,while the control group received the same volume of saline,comparing observed PTH-mediated calcium-sensing receptor in mice the impact of femur fracture model.The results showed that:two weeks later X-ray showed either experimental or control group,with the comparison between the groups of mice,the double knockout mice were significantly reduced compared with wild-type mouse bone callus at the fracture area and the amount of calcification.For four weeks,either the control group or the experimental group,among the same group of mice compared,WT mice fracture lines are more blur and better connect bone fracture.Control group and the experimental group compared with the genotypes,two weeks after modeling,experimental mice femoral fracture callus area and calcification significantly increased the amount,and four weeks after modeling,experimental mice femur fracture and bone fracture lines blur connection is better.HE staining showed callus:After hip fracture modeling one or two weeks we take HE staining of mouse femur in control group and the experimental group.DK mice compared with wild-type mice(WT)fracture callu stotal bone area and bone callus area was significantly reduced.After the model one week or two,compared with genotypes in control group and the experimental group,the experimental group of mice was significantly reduced fracture callus total bone area and bone callus area.Immunohistochemistry showed that:After hip fracture modeling two weeks four weeks,we take normal tissue femur from control group and the experimental group.Whether it is between the control group of mice was compared with the experimental group,DK mice compared with WT mice into cells and osteoclast bone quantity decreased,I collagen positive area,osteocalcin positive area was significantly reduced.Whether the control group and the experimental group compared with the genotypes,the experimental group compared with the control group of mice into mice significantly reduced the number of bone and osteoclasts,I collagen positive area,osteocalcin positive area was significantly reduced.By RT-PCR and Western blot analysis methods are shown:PTH by upregulating CaSR,TRPV-6,bone formation-related genes(core binding factor(Runx2)and IGF-1,activation of MAPK and Wnt signaling pathways promote callus proliferation and differentiation of the bone cells and accelerate fracture fracture healing.Also promote cell proliferation and differentiation of osteoclasts,bone fracture accelerated transformation into bone osteoblasts collaborative role in promoting the healing of femoral fractures.These results can be fully explained exogenous PTH by increasing extracellular calcium concentration,activation of calcium-sensing receptor,result in the proliferation and differentiation of osteoblasts,and ultimately accelerate fracture healing.