Histomorphometry of Bone Microarchitecture in Rats Treated with Vitamin D and Bisphosphonate in the Management of Osteoporosis.

To verify how the combined administration of alendronate (ALN) and vitamin D3 (VD) acts on the bone microarchitecture in rats with glucocorticoid-induced osteoporosis.  The experiment used 32 90-day-old female Wistar rats weighing between 300 and 400g. The induction of osteoporosis consisted of intramuscular administration of dexamethasone at a dose of 7.5 mg/kg of body weight once a week for 5 weeks, except for the animals in the control group. The animals were separated into the following groups: G1 (control group without osteoporosis), G2 (control group with osteoporosis without treatment), G3 (group with osteoporosis treated with ALN 0.2 mg/kg), G4 (group with osteoporosis treated with VD 10,000UI/500μL), and G5 (group with osteoporosis treated with ALN + VD). The right femurs of the rats were fixed in 10% buffered formaldehyde, decalcified, and processed for inclusion in paraffin. Histological sections were stained with hematoxylin-eosin for histomorphometric analysis. Cortical thickness and medullary cavity were measured in cross-sections.  There was a statistical difference (  < 0.05) between groups G3 and G5 compared with the positive control group (G2), both related to the measurement of cortical thickness and to the total diameter of the bone. In the evaluation of the spinal area, only the G3 group has shown to be statistically different from the G2 group.  Concomitant treatment with daily ALN and weekly VD is effective in preventing glucocorticoid-induced bone loss. However, there was no difference between the therapy tested and treatment with ALN alone.