Effect of 17ß-estradiol or alendronate on the bone densitometry, bone histomorphometry and bone metabolism of ovariectomized rats

Abstract

The objective of the present study was to evaluate the effect of 17ß-estradiol or alendronate in preventing bone loss in 3-month-old ovariectomized Wistar rats. One group underwent sham ovariectomy (control, N = 10), and the remaining three underwent double ovariectomy. One ovariectomized group did not receive any treatment (OVX, N = 12). A second received subcutaneous 17ß-estradiol at a dose of 30 µg/ kg for 6 weeks (OVX-E, N = 11) and a third, subcutaneous alendronate at a dose of 0.1 mg/kg for 6 weeks (OVX-A, N = 8). Histomorphometry, densitometry, osteocalcin and deoxypyridinoline measurements were applied to all groups. After 6 weeks there was a significant decrease in bone mineral density (BMD) at the trabecular site (distal femur) in OVX rats. Both alendronate and 17ß-estradiol increased the BMD of ovariectomized rats, with the BMD of the OVX-A group being higher than that of the OVX-E group. Histomorphometry of the distal femur showed a decrease in trabecular volume in the untreated group (OVX), and an increase in the two treated groups, principally in the alendronate group. In OVX-A there was a greater increase in trabecular number. An increase in trabecular thickness, however, was seen only in the OVX-E group. There was also a decrease in bone turnover in both OVX-E and OVX-A. The osteocalcin and deoxypyridinoline levels were decreased in both treated groups, mainly in OVX-A. Although both drugs were effective in inhibiting bone loss, alendronate proved to be more effective than estradiol at the doses used in increasing bone mass.

The effect of alendronate sodium on trabecular bone structure in an osteoporotic rat model

“…Elevated plasma osteocalcin levels following ovariectomy have been reported in previous studies [7][8][9][10] A similar finding was observed in the present study in the Ovx group; however, the alendronate group showed no change in the plasma osteocalcin levels, compared to the Shm group. This finding supports the bone loss in the Ovx group without alendronate supplementation.…”

“…Due to increased life span and the use of more sophisticated diagnostic techniques. The high rate of bone loss in the Ovx rats has been shown to be preventable using similar postmenopausal treatment regimens as in humans [7][8][9][10] As a result, the Ovx rat model is recognized as the gold standard in studies which aim to prevent and slow down osteoporosis in humans. In the present study, we developed an osteoporotic rat model to assess the effects of postmenopausal osteoporosis on trabecular bone formation.…”

O alendronato de sódio na prevenção da osteopenia secundária à imobilização gessada, em ratas: avaliação histomorfométrica

“…Para a confecção do aparelho gessado, os animais foram anestesiados por via intraperitoneal com xylazina 20% (Rompun ® , Bayer) 12mg/ kg e ketamina 10% (Ketalar ® , Parke-Davis) 95mg/kg, como descrito por outros autores (19,23) . Com o animal anestesiado, a região a ser imobilizada foi envolvida por malha tubular e ataduras de algodão.…”

“…As doses utilizadas foram de 0,7mg/ kg aplicadas subcutaneamente no dorso, uma vez por semana, durante 28 dias (12,19) . Os animais foram mortos por meio de dose excessiva de tiopental sódico (Thionembutal ® ) administrado intraperitonealmente.…”

“…Concluí-ram que ambas as drogas foram efetivas, mas a dose de 0,1mg/ kg/dia de alendronato forneceu melhores resultados (19) .…”