We compared similar doses of three different aminobisphosphonates (BP):
olpadronate (OPD),
pamidronate (APD), and
alendronate (ALE) on
osteopenia induced by
thyroxine (T4)-treatment in OVX and
SHAM adult rats. Female Sprague Dawley rats (259 +/- 8 g) were treated with vehicle (SHAM+Vh and OVX+Vh), 250 microg T4/kg/day (SHAM+T4 and OVX+T4), 0.3 mg OPD/kg/day (SHAM+OPD and OVX+OPD), 0.2 mg ALE/kg/day (SHAM+ALE and OVX+ALE), 1.5 mg APD/kg/day (SHAM+APD and OVX+APD), T4+OPD (
SHAM+T4+OPD and OVX+T4+OPD), T4+ALE (
SHAM+T4+ALE and OVX+T4+ALE), and T4 +APD (
SHAM+T4+APD and OVX+T4+APD) during a 5-week period. At the onset and at the end of the experiment, total skeleton bone mineral density (BMD) was assessed in vivo by DXA. Lumbar spine and proximal tibia BMDs were evaluated. T4 treatment to
SHAM rats did not modify BGP levels significantly: neither did
ovariectomy. T4 treatment to OVX rats significantly increased
bone-gla-protein (BGP) levels compared with the other studied groups (P < 0.05). BP treatment reduced BGP levels to values significantly lower than
SHAM rats (P < 0.05) and reduced bone
alkaline phosphatase in
SHAM groups (P < 0.05) but no changes were found in OVX groups. The increased D-Pyr excretion observed in SHAM+T4 rats (P = 0.056), OVX+Vh (P < 0.05), and OVX+T4 group (P < 0.001) compared with the SHAM+Vh rats was prevented by the BP treatment. OVX+Vh rats had total skeleton and proximal tibia BMD, and OVX+T4 group had total skeleton, spine, and proximal tibia BMD significantly lower than the SHAM+Vh group. BP treatment was also found to prevent this reduction. The reduced
bone resorption and the prevention of bone loss showed no differences among very close, potentially equivalent doses of the three aminoBPs used. Consequently, treatment with very close similar doses of APD, ODP, and ALE prevented
bone resorption and bone changes with the same efficacy.