NON-INVASIVE TECHNIQUE FOR THE MEASUREMENT OF BONE REMODELING IN RATS. VALIDATION IN DIFFERENT BIOLOGICAL MODELS

Abstract

Bone remodeling can be measured through bone markers and histomorphometry. This work developed a technique to measure bone resorption (Br) and formation (Bf) in rats, using a mathematical model, fluoremia and renal excretion of fluoride, before and after an intravenous injection of fluoride, in rats. The aim of this work was to validate the method in biological models with modified bone remodeling. Mann Whitney or Kruskal Wallis tests were used to compare two or more groups, respectively. Results are expressed as mean±SEM and differences were considered significant if p <0.05. Each experimental group is composed of 5 rats. The following models in Sprague-Dawley rats were used: 1) Post menopausal osteoporosis induced by ovariectomy without treatment (OVX) and with anti-resorptive treatment with zoledronate (OVX+Z) in 100-day-old rats. Bf and Br were higher in OVX (Bf=1.36±0.56, Br=1.84 ±0.47) than C (Bf=0.50±0.07, Br=0.56±0.38) and OVX+Z (Bf=0.34±0.17, Br=0.45±0.18). 2) Chronic renal failure in 5/6 nephrectomized-100-day-old-male rats (NX). Bf and Br were higher in NX (Bf=5.00±0.40, Br=5.08±0.45) than in C (Bf=0.55±0.14, Br=0.56±0.14). 3) Hypoparathyroidism in parathyroidectomized-140-dayold-male rats (PX). Bf and Br were lower in PX (Bf=0.75±0.08, Br=0.96±0.06) than in C (Bf=1.20±0.32, Br=1.44±0.27). Conclusions: The values of bone resorption and formation are consistent with the expected values for the biological models. The technique is of low cost, mini-invasive and allows the evaluation of different treatments.