Effects of atorvastatin on bone metabolism and bone mineral density in Wistar rats

Objective: To investigate the effects of atorvastatin on bone formation, bone resorption and bone mineral density in Wistar rats. Methods: Sixty healthy male Wistar rats were randomly divided into one control group treated with vehicle alone and three drug treatment groups, which were treated with atorvastatin at 5 mg/kg.d, 25 mg/kg.d and 50 mg/kg.d respectively. Left femur BMD and bone metabolic parameters were measured after 8 weeks of treatment. In high dose of atorvastatin group, 20 rats were randomly allocated into persistent treatment group or atorvastatin washout group for another 4 weeks; bone metabolic parameters were retested. Results: Compared with vehicle alone, atorvastatin treatment significantly increased serum levels of ALP and BGP, but had no effects on serum Ca or P levels. Moreover, atorvastatin significantly decreased bone resorption markers including 24 h urinary Ca/Cr ratio, P/Cr ratio and serum IL-6 level. There was no significant difference among atorvastatin treatment groups. After 4 weeks of washout period, the effects of atorvastatin on bone formation and resorption markers decreased. Atorvastatin treatment did not alter BMD compared with the control group, even in the highest dose of atorvastatin group. Conclusion: Atorvastatin treatment in a certain extent inhibits bone resorption and promotes bone formation, but has no significant effects on bone mineral density in healthy rats.