| Purpose: to investigate the changes of the earlier period in bone metabolism, bone microstructural, bone biomechanics function of rats in type 2 diabetic and insulin resistance, inquirying into type 2 diabetes and insulin resistance whether to cause occurrence of osteoporosis or not, combining inquiry into the first step of its possible mechanism. Method: 40 Wistar rats(specified-pathogens free) of 4 months old in male randomly divided into the 4 groups: A, B, C, D and each one is 10. Among them A is the normal control group, feeding with regular diets, 4 weeks later injects citrate buffer liquid in obdominal cavity; B is the insulin resistance group, feeding with the diets enriched with high-sucrose and high-lipid, 4 weeks later injects citrate buffer liquid in obdominal cavity; C is the type 2 diabetes with insulin resistance group, feeding with the diets enriched with high-sucrose and high-lipid, 4 weeks later injects the aqua of streptozotocin (STZ) by the 30 mg/ kg weight measures; D is the type 2 diabetes group with insulin secretion defaulting, feeding with regular diets, after 4 weeks later injects the aqua of STZ by the 50mg/kg weight measures. Survey rats of bone metabolism indecators, bone density, bone histomorphology, bone histomorphometry, bone biomechanics function etc, combining in situ hybridization technique to observe the BMP2- mRNA expresses in bone tissue. Result: Bone metabolism: Compare with the control group, ALP, TRACP, urine Ca/Cr, urine P/Cr were significantly higher(P<0.05)in Group C, D, Group B has no covariance difference; serum Ca, P, BGP were no difference in four groups; Bone mineral density examination: Compare with the control group, the spine bone mineral density(BMD) were significantly lower in C, D group (P<0.05), group B has no covariance difference; femur BMD, tibia BMD were significantly lower in D group only (P<0.05), B, C groups makes no covariance difference; bone histomorphology: Compare with the control group, trabecular pattern in B, C groups are more intensively, three dimensional structure have no obvious changes; trabecular pattern in D group is sparse, three dimensional structure encounter the obvious breakage; bone histomorphometry: Compare with the control group, percent trabecular area(Tb.Ar%),trabecular number (Tb.N),trabecular thickness (Tb.Th),trabecular separation (Tb.Sp) makes no differences in B, C groups; Tb.Ar%,Tb.N,Tb.Th are significantly lower and Tb.Sp is significantly higher (P<0.05); Bone biomechanics: Compare with the control group, max load, max flexibility, max stress, max strain, energe of lumbar have no covariance difference in the B, C group and are significantly lower in D group (P<0.05); all the index sign of femur makes no difference in B, C group and max stress, max strain, energe are markly lower in group D (P<0.05); in situ hybridization of BMP2- mRNA expresses: Compare with the control group, the average optical density of lumbar, tibia are significantly higher in BMP2- mRNA expression in B, C (P<0.05); the D group has no the covariance difference. Conclusion: Rats in type 2 diabetes and insulin resistance of the earlier period having exsited the changes of bone metabolism and bone mass losing in different degree. In the type 2 diabetes with insulin secretion defaulting, not only exsits the changes of bone metabolism and bone mass losing obviously, but also encounters the microstructural breakage of bone,cause the descent of the bone biomechanics function; in the type 2 diabetes with insulin resistance, there has been the changes of bone metabolism and bone losing partly, but the bone microstructures have no obvious changes; in the insulin resistance group, there weren't changes of bone metabolism and bone losing, the bone microstructures have no obvious changes also, it may have something to do with hyperinsulinism, which is likely to maintain bone microstructure, so bone biomechanics function have no obvious descent both. The hyperinsulinism can cause increment of BMP2-mRNA expression, it may be one of the mechanisms...
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