Diabetic Rat Model Study Of Bone And Cartilage Changes In Morphology And Composition

Objective To establish an animal model similar to the metabolic abnormalities of human type 2 diabetes mellitus with insulin resistance.Discuss this model of bone and cartilage changes in morphology and composition.Methods Eight-week-old SD male rats(n=140) were divided into three groups: model group A and control group B,C.The group A male SD rats(n=60) were fed with high-fatty high sugar diet that contained unsaturated fatty acid for 4 weeks and then streptozotion(STZ,one-step,25mg/kg) was injected intraperitoneally,then streptozotion(STZ,40 mg/kg) was injected intraperitoneally again in the next 4 weeks to result in insulin secretion defect and hyperglycemia,then establishment of model type 2 diabetes;The group B(n=40) were fed with high-fatty high sugar diet;The group C(n=40) were fed with normal diet.All rats in 3 groups were sacrified separately at the 4th,8th,12th,16th week after injected STZ,and the research samples were got at the same time.Detection of calcium,phosphorus,osteocalcin,alkaline phosphatase,bone mineral density,HE staining,staining fan,dual-energy X-ray examination,Ⅱtype collagen extraction etc.Results The second injection of streptozotocin diabetic model prepared into a mold for the 76 percent rate,mortality rate was 19%.In part one,in the 8th weeks compare with the B and C groups,serum AKP were significantly higher in A group(P＜0.05), but decrease in the 16th weeks;In the 12th,16th weeks compare with the B and C groups,serum Ca,BGP were decreased in A group(P＜0.05),serum P continued to decline(P＜0.05),bone mineral density of hip joints,lumbar spine,were significantly decreased in A group(P＜0.05);HE staining under a light microscope suggested the bone trabecular thinning,with disorder.X-ray revealed that the 16th weeks:bone mineral density reduction in cortical thinning.cortical fuzzy edge,joint space narrowing.Electron microscopy showed that the femoral neck bone trabecular thinning with irregular,surface of the collagen fibers arranged in a disorderly manner, loose in A group.In part two,X-ray showed that the 16^th articular cartilage surface roughness,fuzzy,thinning,subchondral bone sclerosis,Dual-energy X-ray showed that:the A group in the 16th weeks bone mineral density significantly decreased than the 8th weeks.HE staining showed that the in the 16th weeks,the cartilage surface irregular,more cracks,decrease in the number of cartilage cells,disorder,periosteal incomplete,bone trabecular structure disorders,bone cells(bone lacuna) decrease, bone cell irregular.Fan staining showed that the 16th weeks:tangent layer cells appeared severely damaged and cluster;in the upper of the transitional shallow,the tangent layer most missing,transitional layer serious damage,cells stained area shallow or even loss of dye.Thinning of the cartilage layer;marginal osteophyte formation;lycopene red O staining showed only a small number of cells around the coloring.Electron microscopy showed that large number of small cracks chondrocytes significant reduction;collagen fibers with irregular and sparse fracture damage..TypeⅡcollagen protein in the 16th weeks the A group significantly lower than the control group significantly(P＜0.01)Conclusion Type 2 diabetes mellitus animal model is successfully reproduced by using the high fatty high sugar diet plus STZ injection.BMD significantly decrease in type 2 diabetes,and may occurrence osteoporosis.The diabetic rat model,CⅡof the articular cartilage increased expression and secretion in the early time,but gradually reduced in the development of the course.And degeneration of articular cartilage from the beginning of tangent,at the same time associated with the destruction of CⅡand development of the deep.