Preserved bone mass in ovariectomized rats treated with parathyroid-hormone-related peptide (1-34) and (107-111)...

The effect of synthetic human PTHrP (1-34) or (107-111) fragments on bone loss was studied in rats, one month after ovariectomy (OVX). Four groups of 7-8-month-old rats were treated sc daily for 13 d with PTHrP (1-34) or (107-111) at the dose of 1 or 3 nmol/100 g body weight. Sham-operated (SHO) and control OVX rats received solvent alone. In our conditions, at the lowest dose, neither (1-34) nor (107-111) fragments had any significant effect. However, at the dose of 3 nmol/100 g daily for 13 d both treatments significantly increased femoral dry weight, ash weight, Ca content and densitometry of the femur. The effect of PTHrP (1-34) mainly resulted from increased cortical and trabecular bone (% recovery: 98.25 and 105.23%, respectively). For the PTHrP (107-111) fragment, a positive effect was only demonstrated on the cortical bone (98.25% recovery). The results of this study demonstrate that both hPTHrP (1-34) and (107-111, osteostatin) fragments are positive for bone when administered at the dose of 3 nmol/100 g body weight/d for 13 d to adult OVX rats.