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

Abstract

Objective To verify how the combined administration of alendronate (ALN) and vitamin D3 (VD) acts on the bone microarchitecture in rats with glucocorticoid-induced osteoporosis. Methods 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. Results There was a statistical difference ( p < 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. Conclusion 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.

Keywords: alendronate; femur; menopause; rats; vitamin D.

Fig. 1

( A ) Measurement of cortical thickness (μm) in femur under final increase of 40X. ( B ) Automatic measurement of the delineated medullary area (μm ² ).

Fig. 2

Histomorphometry of the bone diameter of the femoral diasis of the rats. Average ± standard deviation. Presence of statistically significant difference ( p  < 0.05) between pairs marked with the same superscript symbol.

Fig. 3

Cross-sectional representation of femoral diameter for bone diameter calculation. Adapted from Parfitt et al. .

Fig. 4

Histomorphometry of cortical thickness of the femoral diasis of the rats. Average ± standard deviation. Presence of statistically significant difference ( p  < 0.05) between pairs marked with the same superscript symbol.

Fig. 5

Histomorphometry of the area of the medullary cavity of the femoral diasis of the rats. Average ± standard deviation. Presence of statistically significant difference ( p  < 0.05) between pairs marked with the same superscript symbol.

Fig. 1

( A ) Medição da espessura cortical (μm) em fêmur sob aumento final de 40X. ( B ) Medição automática da área medular delineada (μm ² ).

Fig. 2

Histomorfometria do diâmetro ósseo das diáfises femorais das ratas. Média ± desvio padrão. Presença de diferença estatisticamente significativa ( p  < 0,05) entre os pares assinalados com o mesmo símbolo sobrescrito.

Fig. 3

Representação de corte transversal de diáfise de fêmur para cálculo de diâmetro ósseo. Adaptado de Parfitt et al. .

Fig. 4

Histomorfometria da espessura cortical das diáfises femorais das ratas. Média ± desvio padrão. Presença de diferença estatisticamente significativa ( p  < 0,05) entre os pares assinalados com o mesmo símbolo sobrescrito.

Fig. 5

Histomorfometria da área da cavidade medular das diáfises femorais das ratas. Média ± desvio padrão. Presença de diferença estatisticamente significativa ( p  < 0,05) entre os pares assinalados com o mesmo símbolo sobrescrito.