Effects Of Fluoride, Etidronate And 1, 25-Dihydroxyvitamin D₃ Intervention On The Histomorphometry And Biomechanical Properties Of Bone In Ovariectomized Rats

Fluoride stimulates the bone formation and increases bone mass by means of stimulating mainly proliferation of osteoblast precursors. 1,25-dihydroxyvitamin D., a differentiation agent, can induces differentiation of osteoblast. A recent histomorphometric study demonstrated that fluoride treatment of osteoporosis may result in defect of mineralization and secondary hyperparathyroidism. These findings suggested that the strong stimulus for bone formation brought about by fluoride therapy led to relative calcium deficiency. Thus, use of a combination of fluoride and 1,25-dihydroxyvitamin D₃ can produced greater effect on bone formation by ttimulating both the differentiation and proliferation of osteoblast precursors. 1,25-dihydroxyvitamin D₃can promote intestinal absorption of calcium, correct calcium deficiency, eliminate the defects of mineralization and secondary hyperparathyroidism resulted from fluoride therapy. We supposed a combination of fluoride and 1,25(OH)₂D₃ treatment may increase bone mechanical strength, then enhance antifracture efficacy.Bisphosphonates are analogues of pyrophosphate. They can inhibit osteoclast-mediated resorption of bone, decrease bone turnover by inhibiting the recruitment of osteoclast and differentiation of osteoclast precursors. These effects manifest as decrease of resorption depth and activation frequency in histomorphometric analysis. By which bisphosphonate can decrease "perforation" resorption of trabeculae to protect bone microarchitecture. Althought fluoride can stimulate bone formation, but no effect on bone turnover. In high bone turnover, fluoride may aggravate defect of mineralization, lead to a destroy in mechanical stability of the skeleton,therefore, use of fluoride stimulating bone formation and bisphosphonates inhibiting bone resorption at the same time may augment bone mass, decrease "perforation" resorption, inhibit bone turnover, improve mechanical properties of bone, enhance antifracture efficacy. At present study, 48 four and a half month old virgin female Wistar rats were randomly divided into six groups: ovariectomized group (OVX), sham-operated group, OVX treated with fluoride-Ca (0. 45ngF + 13. 56mg Ca⁺⁺/kg/d) (O+F), OVX treated with combination of fluoride-Ca and 1, 25-dihydroxyvitamin D₃ (0. 45mgF^- + 13.56mg Ca⁺⁺/kg/d + 135pmol 1, 25(OH)₂D₃,/d), (O+F + D), OVX treated with disodium ethane-l-hydroxy-l,1-bisphosphonate (EHDP 1mg/kg/d) (O + EP), OVX treated with combination of EHDP and fluoride-Ca (O+EP+F). Administration in a preventive mode lasted for seven weaks after OVX. We observed the...