| Objective:To establish the model of type 2 diabetes of rats and investigate the relationship between impaired fracture healing and the change of the expression of peroxisome proliferators activated receptor gamma(PPARγ)and core binding factor alpha 1(Cbfal)mRNA in bone marrow of type 2 diabetes rats.Methods:30 physical fitness male Sprague-Dawley rats were divided into control group(10 rats)fed with normal diet and experimental group(20 rats)fed with high fat and sucrosum diet.8 weeks later,all rats were individually intraperitoneally injected with streptozotocin 30mg/kg or citrate buffe.2 weeks later,the rats which fasting blood sugar exceeding 16.7 mmol/L were chosen into experimental group.Onwards, we established the model of distraction osteogenesis in the left tibiae of all the rats.Distraction was initiated the following day at 0.15 mm b.i.d. and continued for 14 days.At the beginning of 15 day,we sacrificed all the rats and collected the blood and left tibiae.Both femora were harvested with germ free.We tested blood glucose,triglyceride,total cholesterol and serum insulin of blood collected at different time points. We observed callus formation in distraction gap by X ray and the formation of primary matrix front and microcolumn formation by histological examination.We also observed the distribution of adipocyte in adjacent bone marrow of left tibia and computed the percentage of adipocyte occuping the area of bone cavity.We measured the expression of PPARγmRNA and Cbfal mRNA in femora marrow by RT-PCR.Results:The levels of triglyceride,total cholesterol,and serum insulin in the experimental group were significantly higher than that of control group(P＜0.01).The level of fasting blood glucose was not obviously different in experimental group(P＞0.05)when compared with control rats after 8 weeks.The levels of fasting blood glucose, triglyceride,and total cholesterol in the experimental animals were obviously elevated in comparison with control group(P＜0.01).The level of serum insulin was not obviously different in experiment group compared with control rats(P＞0.05)at 10 week and when all the rats were sacrificed.Callus formation in distraction gap in experimental group was obviously diminished by X-ray examination.The array of microcolumn formation was disordered and the area of primary matrix front was catachromasis by histology examination in comparison with experimental group.The number of adipocyte in bone marrow and the percentage of adipocyte occuping the area of bone cavity were both increased in experimental group comparied with control group.The expression of PPARγmRNA was up-regulated while Cbfal mRNA was down-regulated by RT-PCR in experimental group. Conclusion:We established the model of diabetes rats through feeding diet with high fat and sugar and intraperitoneal injection of low doze streptozocin.These animals appeared some characters in similar with human type 2 diabetes,such as hyperglycemia,hyperlipemia and insulin resistance.The formation of distraction callus was impaired in the process of fracture healing of type 2 diabetes rats.The expression of PPARγmRNA was increased and Cbfal mRNA was decreased in bone marrow of type 2 diabetes rats.This change may be one of the reasons that caused impaired fracture healing in diabetic rats.
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