Effect of monofluorophosphate (MFP) and zoledronate (Z) on bone mass of rats with modified bone remodelling

BRANCE LORENA; BRUN LUCAS; LUPO, MAELA; ARIAS , LUCAS; RIGALLI, ALFREDO

Córdoba

Congreso; XXVII Reunión anual de la Asociación Argentina de Osteología y Metabolismo Mineral; 2010

p { margin-bottom: 0.21cm; } Bone remodelling is decreased by Z and MFP increase osteoblast (OB) activity. However, the latter is possible if growth factors (GF) are present. High bone resorption releases GF and would enhance MFP effect. Treatment with Z after MFP would maintain high bone mass. This work evaluate this hypothesis. Experiments were carried out in 7-week-old female Sprague Dawley rats (n=7/group). T1: rats with simulated surgery and normal calcium diet (NCaD), T2: ovariectomized (OVX) with NCaD, T3: OVX with NCaD, treated with MFP from day 30 to 90, and with Z from day 91 to 150. T4: OVX with low Ca diet from day 0 to 30, and high Ca from 31 to 150 day. They were treated with MFP and Z as T3. The low Ca diet was administered to produce high PTH secretion, higher osteoclast activity and so more GF for produce OB number. Rats were euthanized at 90 and 150 days. Differences among results (mean±SD) were considered significant if p0.05, ANOVA. Calcemia and phosphatasemia were not different. Histomorphometry of trabecular bone revealed higher bone volume (BV) in T4 (29.411) compared to T2 and T3 (18.22.3, 13.53.2), without differences with T1 (26.311.9). The increase was the consequence of higher trabecular thickness. DMO increased in T3 and T4 respect T2. The ratio OB/OC at the beginning of the treatment with Z (day 90) was higher in T4 compared with T2 and T3. Conclusions: MFP increased BV as the consequence of the increase in trabecular thickness. This effect would be the consequence of high OB/OC ratio induced by high levels of GF produced by a previous higher bone resorption and/or a high Ca diet. MFP is not able to increase bone mass when administered with normal calcium diet.