Effects of PTH (1-84) on bone quality in a validated model of osteoporosis due to androgenic deprivation

Aim: The purpose of this study was to evaluate the effect of parathyroid hormone (PTH) (1-84) in a model of male osteoporosis induced by orchidectomy in rats. Methods: Six-month-old Wistar rats were used as follows: SHAM (simulated orchidectomy), orchidectomized (ORX), ORX + PTH1 (ORX and treated with 10 mu g/Kg/d of PTH 1-84) and ORX + PTH2 (ORX and treated with 50 mu g/Kg/d of PTH 1-84) over 3 months, with treatment beginning three months after orchidectomy. Results: Orchidectomy resulted in a decreased of femoral and lumbar bone mineral density (BMD), a worsening of trabecular and cortical microarchitecture and a decrease in biomechanical properties. Both doses of PTH (1-84) partially (low dose) or totally (high dose) restored the ORX-induced changes. Serum C-telopeptide of type I collagen/5b isoenzyme of tartrate-resistant acid phosphatase (CTX/TRAP) resorption index increased after orchidectomy. Osteocalcin (bone Gla protein; BGP) levels were not affected by orchidectomy. PTH (1-84) treatment did not produce any changes in the levels of CTX/TRAP with respect to the ORX group. BGP levels increased with PTH treatment. Conclusion: PTH (1-84) is able to restore the adverse effects of orchidectomy on bone as measured by BMD, microstructural and biomechanical properties and bone remodeling markers.