Stimulation and inhibition of bone formation: use of peripheral quantitative computed tomography in the mouse in vivo

Abstract

The purpose of this study was to assess peripheral quantitative computed tomography (pQCT) imaging for measurement of volumetric bone mineral density (BMD) in vivo in mouse tibia following ovariectomy, and following treatment with 17 beta-oestradiol (E2). Two studies were undertaken. In study 1, three groups (n = 10) of mature mice were ovariectomized (OVX) or sham operated (SHAM); one of the OVX groups was dosed weekly with E2 (OVX.E2). Images of the proximal tibia were acquired on the day of surgery and at intervals following surgery until week 6. In study 2, four groups (OVX, SHAM, OVX.E2 and a SHAM group dosed with E2, SHAM.E2) of immature mice (n = 10) were imaged weekly up to 10 weeks post-surgery. Precision of pQCT for measurement of total (trabecular plus cortical) BMD was 2.4%, trabecular 5.2% and cortical 2.6%. In mature animals, significantly slower net bone formation was seen in OVX compared with SHAM animals using paired analysis with each animal as its own control. Group analysis detected no significant difference in BMD between SHAM and OVX at any time point. In immature animals, using paired analysis, with each animal as its own control, a significant difference between SHAM and OVX animals was detectable 3 weeks post-surgery (P < 0.05). As in study 1, group analysis of total BMD failed to detect any significant difference between SHAM and OVX at any time point. Treatment with E2 caused an easily-detected increase in BMD and led to osteopetrosis in both groups. The statistical power of this technique is adequate for testing antiresorptive or bone-forming therapies in the mouse.

Abnormal bone composition in female juvenile American alligators from a pesticide-polluted lake (Lake Apopka, Florida).

“…The results of this study suggest that the alligators from Lake Apopka are exposed to estrogenic compounds, because we observed an increase in total and trabecular BMD, a characteristic of estrogen exposure in other vertebrates (Breen et al 1998). A decrease in BMD would have suggested exposure to anti-estrogenic compounds, with osteoporosis as a result.…”

Effects of eccentric exercise training on cortical bone and muscle strength in the estrogen-deficient mouse

“…The effects of estrogen deficiency on bone tissue have been investigated in both human and animal models. Losses in cancellous bone are extensive in both humans and rodents, although the rate of loss in rats exceeds that in both humans and mice (4,5,10,35,44,45). This is accompanied by a significant weight gain in rats, whereas humans and mice show little or no gains in body weight (4,5,10,32,44,45).…”

“…Losses in cancellous bone are extensive in both humans and rodents, although the rate of loss in rats exceeds that in both humans and mice (4,5,10,35,44,45). This is accompanied by a significant weight gain in rats, whereas humans and mice show little or no gains in body weight (4,5,10,32,44,45).Although the effects of estrogen deficiency are well characterized in humans and rodents in cancellous bone, the effects on cortical bone are poorly understood. Understanding the effects of estrogen deficiency on cortical bone is important because some 80% of the human skeleton is cortical bone, the density and geometry of which are primary determinants of bone strength (13).…”

Radiodensitometric and DXA analyses for the measurement of bone mineral density after systemic alendronate therapy

“…6 Bone densitometry facilitates the early diagnosis of metabolic bone diseases associated with intense bone resorption, such as osteopenic and osteoporotic conditions, and this method can be used to monitor treatment efficacy, thereby significantly decreasing the incidence of pathological fractures. 7 Some non-invasive imaging technologies, such as magnetic resonance imaging (MRI), ultrasound, computed tomography (CT), dual-energy x-ray absorptiometry (DXA) 8 and radiographic densitometry, 1 have been employed in medical diagnosis for different purposes. Furthermore, periapical and panoramic radiography techniques, which are commonly used in dental practice, could also be useful for the detection of bone disorders.…”

“…de Balanças Ltda., Toledo, Brazil) so that the dose of sodium alendronate solution light intensity was the proximal tibial metaphysis, as in most of the bone biology studies. 8,16,17 The values that were obtained from each step of the aluminum stepwedge were used to calibrate the software and as references for the sample values. After three radiographs were obtained of each specimen, a mean BMD value was calculated for each group (sodium alendronate group and control group).…”