Study On Changes Of Bone Metabolisim And Its Mechanisim In Apolipoprotein E Knickout (ApoE-/-) Mice

Part one Varience of blood biochemical markers in apolipoprotein E knockout(ApoE/-) miceObjective:To investigate the changes of blood biochemical markers in 28-week-old male apolipoprotein E knockout(ApoE-/-) knockout mice.Methods:There were 16 mice including ApoE-/- mice(n=6) and sex-age-matched C57BL/6J mice(WT,n=10) involved in the study.The mice were euthanized,bloods were collected from retro-orbital venous plexus,and the sera were separated.The following indexes determined, such as triglycerides(TG),total cholesterol(TC),low density lipoprotein cholesterol(LDL-C),high density lipoprotein cholesterol(HDL-C), apolipoprotein B(ApoB),high sensitivity C-reactive protein(hs-CRP), non-esterifed fatty acid(NEFA),creatine kinase(CK),creatine kinase-isozymesisoenzymes(CK-MB),lactate dehydrogenase(LDH) and albumin ischemia-modified(IMA).Results:The levels of TG,TC,LDL-C,hs-CRP,ApoB and NEFA were 0.57±0.15 mmol/L,12.93±3.57mmol/L,1.43±0.71 mmol/L, 0.14±0.06 mmol/L,0.16±0.04g/L and 3.20±0.55 mmol/L,respectively, which were higher than those in WT mice with the lower level of HDL-C (0.46±0.16mmol/L).Compared with the WT mice,the myoenazyme parameters CK and LDH were increased in ApoE-/- mice with a lower lever of IMA,and the concentration of CK-MB were increased but no statistical significance.Conclusion:The results indicated that changes of blood biochemical parameters were closely related to atherosclerosis in ApoE -/- mice and companied with damage of myocardial function.Part two Changes in bone mineral density,microarchitecture with advancing age in the male apolipoprotein E knockout(ApoE -/-) miceObjective:To study the changes of bone mineral density(BMD) and microarchitecture in apolipopritein E knockout(ApoE -/-) mice.Methods:15-week-old,28-week-old and 40-week-old male ApoE -/-mice and sex-age-matched wild-type(WT) mice were involved in the study.The trabecular and cortical bone microarchitecture were assessed by micro-CT(μCT) in the right distal femur.The total body BMD of the left femur was determined by dual-energy X-ray absorptiometry (DXA).The relationships among the BMD,microarchitecture and BMC were analyzed.Results:Compare with WT mice,the advancing age ApoE -/-mice showed a increased volumetric BMD(vBMD),tissue BMD(tBMD),bone mineral containt(BMC),bone volume fraction(BV/TV),trabecular number(Tb.N),trabecular thickness(Tb.Th) with an decreased bone surface fraction(BS/BV),trabecular separation(Tb.SP) and the structure mode index(SMI).The cortical bone microarchitecture parameters as inner perimeter(In.Pm),outer perimeter(Ot.Pm),cortical area (Ct.Ar),marrow area(Ma.Ar),Total area(Tt.Ar) and moment of inertia (Mm) were also increased,but cortical BMD(Ct.BMD),cortical bone mineral containt(C.BMC) and cortical thickness(Ct.Th) retained constant.At the ages of 28 weeks,the total body BMD in ApoE -/- mice revealed higher than WT mice and there was no changes in 15-week-old and 40-week-old mice.Compared with the sex-age-matched controls, vBMD positively correlated with BMC,BV/TV,Tb.Th,BS/BV and C.BMC with the correlation coefficients were 0.955,0.944,0.834,0.923 and 0.903,respetively,and there was a better positive correlation between vBMD and other indices as SMI,C.BMD,Ot.Pm and Ct.Ar but there were no statistically significant.And there were no correlation between VBMD and the other parameters.Conclusion:ApoE -/-mice displayed an increased bone mass,which showed that ApoE has an important role in bone metabolism. Part three The preliminary study on mechanism of increased bone mass in mice knocking out Apolipoprotein ESubject:To investigate mechanisms of increased bone mass in mice knocking out Apolipoprotein E(ApoE-/-).Method:There were 28-week-old male ApoE-/- mice(n=6) and wild-type(WT) mice(n=10) involved in the study.All mice were euthanized,bloods were collected from retro-orbital venous plexus,and sera were collected.Automatic biochemical analyzer was used to determine the biological parameter alkaline phosphatase(ALP), phosphorus(P),calcium(Ca) and gamma-glutamytransferase(γ-GT).The concentration of osteoprotegerin(OPG) and receptor activator of nuclear factorκB ligand(RANKL) in sera were analyzed using enzyme-linked immunosorbent assay(ELISA).The left tibias were dissected,and then the tibias were fixed in 4%paraformaldebyde after decalcified in 0.15M EDTA buffer for 30 days,the expression of PPG and RANKL were finished by immunohistochemical staining.Results:Compared with WT mice,the concentration of OPG displayed a significant high level,ALP activity was decreased accompanied by no apparent changes in the serum concentration of Ca.P andγ-GT.OPG expression was observed at higher levels in bone cell of ApoE-/- mice with RANKL was no obviously change. Conclusion:An increased bone mass in ApoE-/- mice might be caused by a decreased bone resorption that induced by the imbalance of the ratio of RANKL/OPG...