| Objective:1. To investigate the changes of blood glucose,weight,BMD(bone mineral density) andbone turnover markers in high sucrose-fat diets with STZ- induced diabetic rats bymetformin.2. Observation the relationship between the diabetic rats bone protection bymetformin and the endoplasmic reticulum stress.Methods:1. Diabetes rat model: 60 male sprague-dawlry(SD) rats were randomly dividedinto normal control group(NC group,n=15) and model group(n=45). Normal controlgroup was fed with standard chow, while model group was fed with high sucrose-fatdiets(HSFDs) for 8 weeks, the model group were injected intraperitoneally withstreptozotocin(STZ, 30mg/kg) while the ones in group NC were injectedintraperitoneally with the similar dose of normal saline. Subjects with FBG higherthan 16.7mmol/L in three consecutive days were successfully modeled.2. Pharmaceutical intervention: 30 modeled rats were grouped into Type 2 diabetesmellitus group(T2DM group,n=15) and metformin treated group(MF group,100mg/kg·d, n=15). After 2 weeks, the thervention by metformin.Group NC andgroup T2 DM were gavaged equal physiological saline. Group NC were fed with thestandard chow, while the remaining two groups were fed with HSFDs.After 20 weeksdetecting the blood glucose and weight of each group rats.3. The detection of BMD and bone turnover markers: DEXA was used to measureeach part of whole body bone mineral density(BMD). The serum OCN and TRACP5 bactivity were detected by ELISA; AMP-buffer tested serum ALP level.4. Hematoxylin eosin staining(HE): HE staining observation the pathology changeof the bone.5. The detection of gene and protein: RT-PCR and western blot detected the m RNAand protein expression of ATF6、CHOP、JNK、Caspase12of the femur respectively.Results:1. After sitagliptin treatment for 20 weeks, compaired with group NC, FBGincreased significantly(P<0.05), while body weight in group MF decreased obviouslyin group T2DM(P<0.05). FBG increased in group MF(P>0.05),body weight has nosignificant difference(P<0.05). Compaired with group T2 DM, FBG in group MFdecreased significantly(P<0.05), while body weight increased obviously(P>0.05).2. Compaired with group NC, BMD of lower limbs, upper limbs, trunk, spine andwhole body in group T2 DM decreased, especially in lower limbs, upper limbs andwhole body BMD(P<0.05), while BMD of lower limbs, upper limbs, spine and wholebody in group MF decreased(P>0.05), while trunk increased(P>0.05). Compairedwith group T2 DM, the BMD of lower limbs, upper limbs and whole body BMDincreased obviously(P<0.05).3. Compaired with group NC, the expression of serum ALP decreased(P<0.05),OCN decreased(P>0.05), TRACP5 b increased(P<0.05) in group T2 DM, theexpression of serum ALP increased(P<0.05),OCN increased(P>0.05), TRACP5bincreased(P<0.05)in group MF.Compaired with group T2 DM,the expression of serumALP and OCN increased(P<0.05), TRACP5 b decreased(P<0.05)in group MF.4. The groups of the pathological changes of the bone after HE staining: Compairedwith group NC,the bone of group MF,bone trabecular thick, slightly narrow spacing.fuzzy bone marrow tissue is visible, bone marrow cavity is Narrow. Compaired withgroup T2 DM,the bone of group MF, bone cortex of rats bone plate levels clear,structure is compact. trabecular bone is neat, Bone cells are clear and completenuclear assunes the circular or ovoid,large,is located in the central.Vacancy pit bonecells is rare.5. The intervention of MF for 20 weeks,Compaired with group NC,The m RNAexpression of ATF6, CHOP, Caspase12, JNK in rat femur were significantlyincreased(P<0.05) in group T2 DM. The m RNA expression of ATF6, CHOP,Caspase12, JNK in rat femur were significantly increased(P<0.05) in groupMF.Compaired with group T2 DM, The m RNA expression of ATF6, CHOP,Caspase12, JNK in rat femur were significantly decreased(P<0.05) in group MF.6. The intervention of MF for 20 weeks,Compaired with group NC,The proteinexpression of ATF6, CHOP, Caspase12, JNK in rat femur were significantlyincreased(P<0.05) in group MF. Compaired with group T2 DM, The proteinexpression of ATF6, CHOP, Caspase12, JNK in rat femur were significantlydecreased(P<0.05) in group MF.Conclusions:1.Metformin can effectively reduce the high fat and sugar in combination withsmall dose of STZ induced diabetic rats fasting glucose2. Metformin intervention in diabetic rats can promote bone formation, inhibit boneabsorption Increasing diabetic rats new bone and bone mineral density3. Metformin may by reducing diabetic rats ATF6, CHOP, Caspase12, theexpression of JNK, influence of endoplasmic reticulum stress on osteoblast functionPlay the role of bone protection of the diabetic rats... |
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