D-15 Free Communication/Slide - Exercise and Bone I: MAY 28, 2009 1:00 PM - 3:00 PM: ROOM: 619
Simvastatin is a statin, which are a class of drugs originally developed to fight cardiovascular disease by lowering cholesterol. However, it is now clear that they have broad effects independent of cholesterol. For example, statins have also been shown to stimulate bone formation in vitro by promoting bone morphogenic protein-2 (BMP-2) activity and to stimulate bone formation in vivo. However, post hoc observational studies of statin trials are inconclusive on whether fracture risk is lower among statin users than age-matched, non-users, despite the apparent anabolic effect in vivo.
PURPOSE: To test the hypothesis that exercise in combination with oral simvastatin synergistically increases bone mineral density and strength.
METHODS: Retired breeder, female, Sprague Dawley rats were divided into 4 groups: control (n = 9), statin only (n = 8), exercise only (n = 11), and statin plus exercise (n = 11). Simvastatin was given to the two groups at a dose of 10 mg/kg/day in standard rat chow. All rats ate the same mass of food. The two exercise groups ran on a treadmill for 5 days/week at an intensity of about 70% VO2max and for a duration that was gradually increased to 60 min/day. After 5 weeks, rats were euthanized, and excised femurs were scanned for bone mineral density (BMD) and tested by three point bending to obtain structural strength, stiffness, and toughness.
RESULTS: Only the combined group treated with statins plus exercise showed a positive effect on the biomechanical performance of the femurs. Compared to controls, this group had increased maximum force, stiffness, BMD, and moment of inertia. The increase in maximum force was related in part to an increase in BMD.
CONCLUSION: The combination of oral statins and exercise using a treadmill may provide optimal protection against bone fracture.
Supported by Am Heart Assoc - Texas Affiliate