Anabolic effect of olpadronate: Histochemical study of alkaline phosphatase

Bisphosphonates (BPs) are drugs used to treat several bone diseases, mainly osteoporosis. BPs are classified as antiresorptive agents, their antiresorptive action is due to direct inhibitory effects Qn osteoclasts. Recently, in vitro studies have reported that BPs may have an anabolic effect Qn bone osteoblastic celis in 10w concentrations. Monosodic olpadronate (OPD), belongs to the amino BPs group, which are actually the most potent BPs. The objective of the present study was to evaluate, in interradicular bone from healthy experimental animais, the anabolic effect of OPD by means histochemical detection of alkaline phosphatase (ALP). ALP ¡s an enzyme related to formation/mineralization of bone matrix. For this purpose, 10 female Wistar rats aging 60±10 days and 160±10 gr of body weight were divided into two groups: Sham (Sh): 
received vehicle and OPD: received 0.3 mg/kg/week of OPD via ip. during 5 weeks. Six weeks after the onset of the experiment, the animais were killed and the mandibles were dissected, fixed in PBS formaldehyde and decalcified. Left hemi mandible was processed for H&E staining and right hemi mandible was processed for histochemical detection of ALP. Mesio-distal sections of the Iower first molar were obtained for both techniques and histomorphometric parameters were evaluated in interradicular bone. Results: Bone activity evaluated in H&E sections showed no differences between groups. ALP detection showed an increase in the percentage of surfaces covered by positive osteoblasts and lining cells in OPD treated group (Sh: 31.8 ± 7.8, 
OPD: 60.3 ± 7.2, p