| BackgroundDiabetes(diabetes mellitus,DM)is characterized by high blood sugar metabolic disease,caused by insufficient insulin secretion or insulin resistance.In recent years,the global prevalence of diabetes has remained high,and it has been increasing year by year.With the development of our country's economy and the improvement of people's living standards,the high sugar and fat diet has led to a significantly higher incidence of diabetes than in the past.Diabetes can cause a variety of complications,including cardiovascular disease,kidney disease,nervous system disease,retinal disease,etc.At the same time,it can also change bone cell metabolism and affect osteoblast mineralization,so it is one of the diseases that endanger public life and health Osteoporosis(OPeoporosis,OP)is a slow-moving metabolic bone disease,which is mainly characterized by low bone mass and damage to the microarchitecture of bone tissue.It is related to increased bone resorption and reduced bone formation.It is clinically manifested as bone Increased brittleness and prone to fractures.Osteoporosis is often accompanied by degenerative changes in the spine,and spinal fusion is a common method for treating spinal diseases.Studies have found that diabetes is one of the risk factors for adverse outcomes of spinal surgery.Parathyroid hormone(PTH)is produced and released by the parathyroid gland.It is one of the important hormones in the human body.It has the effects of increasing blood calcium,reducing blood phosphorus and acidifying blood.PTH can improve the biological activity of osteoclasts and promote the bone resorption process,so that bone calcium is released and enters the blood circulation.At the same time,it can increase the number of osteoblasts,increase the production of osteoblasts and release bone growth factor.Ability,which in turn promotes bone formation and increases bone mass.Bone morphogenetic protein(BMP)is one of the osteoinductors that has been researched in recent years.It is considered to be the strongest osteoinductive differentiation factor,which has a regulatory effect on cell proliferation,growth,differentiation,and apoptosis.At the same time,it can promote bone formation.BMP-2 is one of the important members of the BMP family,which can promote the bone formation and healing process.BMPR2 is a receptor for BMP-2,and BMP-2 and BMPR2 can play biological functions immediately.A large number of animal studies have confirmed that BMP-2 plays a promoting role in the process of spinal fusion regulation.However,the effect of BMP-2 on spinal fusion in osteoporotic spinal fractures is still lacking,especially its effect on spinal fusion in diabetic osteoporosis.The mammalian target of rapamycin(mTOR)is an atypical serine/threonine protein kinase.mTOR can regulate the translation,transcription,and synthesis of cellular proteins based on the obtained stimulus information.Thereby affecting the role of cell size,tissue and organ morphology.At present,most researchers believe that the mTORCl signaling pathway can promote osteoblast differentiation,and mTOR activation is also a necessary condition for the survival of osteoclast precursors and mature osteoclasts.However,there are no reports about the role of mTOR in diabetic osteoporosis.Phosphatidylinositol 3-kinase(PI3K)is a type of kinase that specifically catalyzes phosphatidylinositol substances.It can regulate the activation of various cytokines,and can promote tissue cell proliferation and differentiation.It also plays an important role in the process of apoptosis.PI3K has a significant effect on the function of osteoblasts and osteoclasts,and is related to the process of bone formation and bone resorption.Studies have found that when the expression of PI3K is inhibited,it can block BMP-2 mediated ?-catenin activation,thereby affecting the differentiation of bone marrow stem cells into osteoblasts.Spinal fusion surgery is the main method for clinical treatment of spinal diseases.However,some observational studies and interventional studies have shown that diabetes can have an adverse effect on orthopedic surgery.Diabetes is one of the main risk factors for perioperative complications and poor surgical outcomes in spinal surgery.ObjectiveThe purpose of this study is to determine whether PTH can play a role in improving osteoporosis through the mTOR/PI3K signaling pathway,and to explore the impact of diabetes on these effects.Methods(1)92 male SD rats were randomly divided into 2 groups,of which 48 rats were injected with STZ to establish a diabetes model,and the other 44 rats were injected with the corresponding normal saline.After 4 weeks of continuous injection,the blood glucose concentration of the rats was measured.Spinal fusion surgery was performed on the rats,and the rats were divided into a diabetic group and a non-diabetic group,and each group was further divided into a control group and a hPTR group,and saline and hPTH were injected,respectively.The levels of BMP-2 in the serum of each group of rats were detected.Spine samples were collected after the rats were sacrificed,and the expressions of BMPR2 protein,p-mTOR and p-PI3K protein in bone tissue were detected.HPTH,hPTH+Rapamycin/hPTH+LY294002 were applied to diabetic or non-diabetic rats after spinal fusion,and the levels of BMP-2 in serum and BMPR2 protein expression in the spine were detected.(2)ROS1728 cells were randomly divided into non-high glucose group and high glucose group,and each group was divided into control group and hPTH group.HPTH was added to the hPTH group cells.The proliferation activity and apoptosis of cells in each group were detected.The expressions of BMP-2 and BMPR2 mRNAs were detected in each group of cells,and the expressions of BMP-2,BMPR2,p-mTOR and p-PI3K proteins were detected.HPTH,hPTH+Rapamycin/hPTH+LY294002 were applied to ROS1728 cells in a non-high or high glucose environment,and the expressions of BMP-2 and BMPR2 proteins in the cells of the above groups were detected.Results(1)The results showed that in rats injected with normal saline,the levels of serum BMP-2 and expression of BMPR2,p-mTOR and p-PI3K protein in bone tissue were significantly increased after hPTH administration(P<0.05);In the STZ-injected rats,the serum BMP-2 levels and the expression levels of BMPR2,p-mTOR,and p-PI3K protein in bone tissue after hPTH administration were not significantly different from those in the control group.In rats injected with normal saline,the levels of BMP-2 in serum and expression of BMPR2 protein in bone tissue after hPTH administration were significantly higher than those in the control group(P<0.05);when rapamycin or After LY294002 was applied to rats,the above promotion of BMP-2 and BMPR2 protein expression was inhibited.The levels of BMP-2 in rat serum and BMPR2 protein in bone tissue were not significantly different from those in control group.In rats injected with STZ,there was no significant difference in the levels of BMP-2 in serum and the expression of BMPR2 protein in bone tissue after hPTH administration compared with the control group;After mice,the levels of BMP-2 in the serum of the rats and the expression of BMPR2 protein in the bone tissue were not significantly different from those in the control group.(2)In ROS1728 cells under non-high glucose environment,the proliferative activity of cells after administration of hPTH was significantly higher than that in the control group(P<0.05),and the apoptosis rate was significantly reduced(P<0.05);while under high glucose environment After the hPTH administration,the proliferation activity and apoptosis rate of ROS1728 cells were not significantly different from those in the control group.In ROS1728 cells under non-high glucose environment,the expression levels of BMP-2 and BMPR-2 mRNA and protein,p-mTOR and p-PI3K protein expression levels in cells after hPTH administration were significantly higher than those in control group(P<0.05);in high glucose environment,the expression levels of BMP-2 and BMPR-2 mRNA and protein,p-mTOR and p-PI3K protein in ROS1728 cells after hPTH administration were not significantly different from the control group.In a non-high glucose environment,the expression levels of BMP-2 and BMPR2 protein in ROS1728 cells after hPTH administration were significantly higher than those in the control group(P<0.05);and when the mTOR inhibitor rapamycin was applied to the cells,The promotion effect of hPTH on the expression of BMP-2 and BMPR2 protein was inhibited,and the expression level of BMP-2 and BMPR2 protein in cells was not significantly different from that in the control group;when PI3K inhibitor LY294002 was applied to the cells,hPTH The expression of BMP-2 and BMPR2 protein had no effect,and the expression levels of BMP-2 and BMPR2 protein in cells had no significant difference compared with the control group.In the high glucose environment,the expression levels of BMP-2 and BMPR2 protein in ROS1728 cells after hPTH administration were not significantly different from those in the control group;when rapamycin was applied to rats,BMP-2 and BMPR2 in cells Compared with the control group,the protein expression level was not significantly different;when LY294002 was applied to the cells,hPTH had no effect on the expression of BMP-2 and BMPR2 proteins,and the expression levels of BMP-2 and BMPR2 proteins in the cells were similar to those in the control group There is no significant difference.Conclusions(1)The mTOR/PI3K signaling pathway is involved in the regulation of hMPTH on BMP-2 and BMPR2.Under diabetic conditions,hPTH's activation of the mTOR/PI3K signaling pathway is weakened,inhibiting the expression of BMP-2 and BMPR2,and ultimately affecting bone formation after spinal fusion.(2)The mTOR/PI3K signaling pathway is involved in the regulation of hMPTH on BMP-2 and BMPR2.In high glucose environment,hPTH activated the mTOR/PI3K signaling pathway in osteoblasts and weakened the expression of BMP-2 and BMPR2. |
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