Evaluation Of Preventative Effect Of Simvastatin On Glucocorticoid-induced Osteoporosis And The Effect On Serum IGF-Ⅰ Level

Objective To evaluate the preventative effect of simvastatin on glucocorticoid-induced osteoporosis and to observe the effect of simvastatin on serum IGF-I level to investigate it's mechanism of action.Methods 30 3.5-month-old male SD rats were divided into three groups randomly: model group (A), control group(B) and treatment with simvastatin group(C). In this study, osteoporosis was induced by subcutaneous injection with methylprednisolone 3.5 mg/kg per day for 9 weeks. The control group rats were treated by subcutaneous injection with Sodium Chloride 1.64ml/kg per day for 9 weeks. The treatment with simvastatin group rats were treated with glucocorticoid for 9 weeks and in combination with simvastatin 4 mg/kg per day by stomach for 10 weeks. After the treatments, some indices such as bone mineral densities(BMD),serum osteocalcin(BGP),insulin-like growth factor-I (IGF-I) ,urine Ca2+/Cr and urine P/Cr were measured. BMD is the standard judging success of inducing osteoporosis model. BGP is the index reflecting bone formation. Urine Ca2+/Cr and urine P/Cr are the indices reflecting bone resorption.Results After the subcutaneous injection with methylprednisolone for 9 weeks, compared with the control group, BMD was decreased significantly(P<0.01) in the model group .It indicated that osteoporosis was successfully induced by glucocorticoid. The level of serum BGP and IGF-I were lowered significantly(P<0.01).The serum Ca2+ and urine Ca2+/Cr were increased(P<0.01). The urine P/Cr was increased, too(P<0.05). All these supported the case that osteoporosis was successfully induced by glucocorticoid.After the treatment by simvastatin for 10 weeks, compared with the model group, simvastatin significantly increased BMD and serum BGP(P<0.01), while decreased the level of urine Ca2+/Cr(P<0.01),but didn't influence obviously the level of serum IGF-I (P>0.05).Conclusion (1)Simvastatin has preventative effect on glucocorticoid-induced osteoporosis of rats. (2)Maybe its role of improving bone formation has nothing with IGF-I.