The Effect Of Simvastatin On BMD And N-terminal Telopeptide Of Type â…  Collagen In STZ-diabetic Rats

Objective: Some recent researches have show that statins have some influence on bone metabolism besides its fat adjustment. Most researches paid close attention mainly about its promotion to bone formation, and few reports showed that statins can restrains bone absorption. This experiment was designed to observe if simvastatin can hold back the development and progression of osteoporosis through restraining bone absorption, then we can provide experimental base for the prevention and treatment of osteoporosis related to diabetes mellitusMethod :24 healthy male Wistar rats (provided by Experimental Animal Centre of Anhui Medical Graduate School, two months old, 200±20g weight, with blood glucose up to snuff before experiment) were randomly assigned t three groups. normal control group (groupA,n=8), diabetic rats group( groupB,n=8) and simvastatin(20mg/kg/d) treatment group (group C, n =8). After diabetic models were estabished, group C were given simvastatin (MERCK China C.Ld) 20mg/kg each day ( with simvastatin dissolved in distilled water). Group A and Group B were given equal distilled water. The peripheral blood glucose at the 2nd , 4th , 8th week, and N-terminal telopeptide of type I Collagen (NTX) at 2nd and 8th week(24 hours urine) were measured with enzyme-linked immunosorbent assay( ELISA). By the 8th week, rats were killed to collect blood and bone specimen, the blood NTX was measured by ELISA, the bone mineral density(BMD) of lower limbs was measured by Dual Energy X-ray Absorptiometry(DXA), Bone specimen of lower limbs from rats of each group were kept to observe their morphology under light microscope.Results:(1)The peripheral blood glucoses of group B and group C at the 2nd and 8th week of were markedly higher than that of Group A(P<0.01), there was no statistical difference between Group B and group C(P>0.05). (2)The 12 urine NTX in group B and group C by the end of 2nd week was markedly higher than that of group A(P<0.01), the urine NTX of the 8th week of group B was higher than that of the 2nd week. The urinary NTX of group C declined markedly after statins treatment, and the difference has statistical meanings(P<0.05), but still higher than that of the group A. (3)The blood NTX of group B and group C was markedly higher than that group A(P<0.01), but the level in group C declined greatly when compared with that of group B after treatment with statins. (4)The BMD of group B and group C declined markedly compared with group A; The BMD of group C was higher than that of group B after the treatment with statins, and the difference had statistical signficant(P<0.05), but still lower much than that of group A, and the difference had statistical significance, too(P<0.01). (5)Compared with group A, the bone trabecula of group B markedly turned thin, sparseness and rupturable under light microscope(1:400) with much adipose tissue. the bone trabecula in group C had became better in osteoporosis after treatment with simvastatin for 8weeks, but still had distinct osteoporosis characteristic under light microscope.Conclusion: Simvastatin has some protective effect against osteoporosis in STZ-induced diabetes rats , which may be partly related to its effect in inhibting bone absorption, exact mechanisms need to be evaluated futher.