Systemic bone formation with weekly PTH administration in ovariectomized rats.

PURPOSE: Weekly subcutaneous administration of 0 (vehicle), 10 and 80 microg/kg doses of human parathyroid hormone (1-34) [PTH (1-34)] were compared based on their capacity to induce systemic formation of bone in 9 month-old ovariectomized (OVX) Sprague-Dawley rats. METHODS: Changes elicited at bone tissue after 4 weeks of treatment were assessed using dual x-ray absorptiometry, micro-computed tomography (microCT), and ashing. RESULTS: The 10 microg/kg dose led to a significant increase (p<0.025) in femoral bone mineral density (BMD) over vehicle- and 80 microg/kg-treated groups. Similarly, structural analysis of the femoral neck trabecular bone by microCT revealed increases in bone volume fraction and trabecular thickness over the pre-treatment baseline, and vehicle- and 80 microg/kg-treated groups. CONCLUSIONS: The data suggest that the weekly administration of 10 microg/kg of PTH (1-34) was sufficient to significantly promote the bone mineral density systemically. The weekly administration of 10 microg/kg over a 4-week treatment period is, to our knowledge, one of the lowest reported total dose of PTH (1-34) shown to induce a net anabolic effect on skeletal tissue in OVX rats.