Differentiating between orchiectomized rats and controls using measurements of trabecular bone density: A comparison among DXA, Histomorphometry, and peripheral quantitative computerized tomography

Abstract

In studies of rat bone metabolism, trabecular bone density should be measured. Three established methods of measuring trabecular bone include trabecular bone volume by histomorphometry (BV/TV%), trabecular bone density by peripheral quantitative computerized tomography (pQCT), and areal bone density of trabecular-rich regions by dual x-ray absorptiometry (DXA). We compared the ability of these three methods to discriminate between orchiectomized (orchidectomized) rats and controls. Sixteen male Sprague-Dawley rats (400-425 g) were orchiectomized, and 16 others were controls. In vivo spine bone mineral density (BMD) was measured at the beginning of the study and again after 11 weeks. Rats were sacrificed, and ex vivo BMDs of the right femur and tibia were measured by DXA, followed by trabecular bone density of the right proximal tibia by pQCT. BT/TV% of the left proximal tibia was measured by histomorphometry. Differences between groups were detected by all three methods, but both the magnitude of the difference between groups and the variance of the measurements was much greater for histomorphometry and pQCT than for DXA. Consequently, the statistical significance for the difference between groups was comparable for all three methods. Of the sites measured with DXA, the proximal tibia had the greatest statistical significance for the difference between groups. In summary, all three methods can demonstrate the effect of orchiectomy on trabecular bone. The large differences between groups seen by histomorphometry are also seen by pQCT but not by DXA. We conclude that trabecular bone density by pQCT may be a reasonable surrogate for measurements by histomorphometry.

Density and structural changes in the bone of growing rats after weekly alendronate administration with and without a methotrexate challenge

“…Cortical bone was defined by a voxel density greater than or equal to 700 mg/cm 3 , soft tissue by a voxel density of less than or equal to 400 mg/cm 3 , and trabecular bone by a voxel density between 400 and 700 mg/cm 3 . 29,30 The trabecular medullary compartment was defined by the region interior to the endosteal surface of the cortex with a voxel density less than 700 mg/cm 3 .…”

Pharmacological treatment of osteopenia induced by gastrectomy or ovariectomy in young female rats

“…pQCT was performed with the Stratec peripheral quantitative computed tomograph (pQCT) XCT Research M (Norland Corp., Fort Atkinson, WI) specifically modified for use on small bone specimens (software version 5.4B; operating at 70 µm resolution) (Rosen et al 1995, Andersson et al 2002. The machine was calibrated with a standard of hydroxyapatite embedded in acrylic plastic.…”

Alcohol and Adaptation to Mechanical Usage

“…In the current study, LS was measured as an index of osteoblast number, and MAR was calculated as an index of osteoblast activity (35). As previously shown, 06/07/00 Endocrinology Page 10 the increase in LS was largely responsible for the PTH-induced increase in bone formation (29,33,34).…”

“…Studies performed in growing male (21,(32)(33)(34)(35) and female (36,37) rats demonstrated that chronic consumption of large doses of alcohol in the diet suppresses bone growth. The resulting relative osteopenia is due to the failure to acquire a normal bone mass and is relevant to juvenile alcohol abusers.…”

“…A direct inhibition of osteoblast proliferation is supported by the work of Klein et al,(26) who have shown that ethanol decreases by locally produced as well as systemic factors (27,(33)(34)(35)(36) (4)(5)(6)(7)(8)(9)(10)(11)(12)(13). The effects of ethanol on bone resorption are less certain; increases, decreases and no change have been reported (2,(4)(5)(6)(7)11,13).…”