Histomorphometry of the organic matrix of the femur in ovariectomized rats treated with sodium alendronate☆

OBJECTIVE To evaluate the effect of two different concentrations of sodium alendronate on the quantity of organic matrix in the femur of rats with estrogen suppression caused by ovariectomy. METHODS Sixty-days-old Wistar rats (Rattus norvegicus) were subjected to bilateral laparotomy to remove the ovaries. The animals were divided into a control group, in which they only underwent laparotomy; an ovariectomized group (OVX); an ovariectomized group treated with 1 mg/kg of alendronate (OVX 1 mg); and an ovariectomized group treated with 2 mg/kg of alendronate (OVX 2 mg). The rats received alendronate twice a week for 90 days. The left femur was then removed, fixed and processed for embedding in paraffin. Semi-serial sections stained with hematoxylin and eosin were used to determine the area occupied by organic bone matrix, by means of image analysis software. The animals' weights were obtained at the beginning and end of the experiment. RESULTS The ovariectomized animals and those treated with 1 mg/kg of alendronate presented significant increases in body weight (p < 0.05), in comparison with the control group. Histomorphometric analysis revealed that in the animals treated with 2 mg/kg of alendronate, the area (μm(2)) occupied by organic matrix (1,81,900 ± 18,130) was similar (p > 0.05) to that of the non-ovariectomized control animals (2,04,800 ± 9590), which indicates that this medication had a preventive effect with regard to bone mass loss. CONCLUSION The higher concentration of the medication, administered twice a week for 90 days, was more effective than the dose of 1 mg/kg over the same period.