title: Bone loss detection in rats using a mouse densitometer.
abstract: Estrogen-depletion bone-loss studies often use ovariectomized (ovx) rats and measure bone mineral density in vivo or ex vivo using DXA. Recently, a portable densitometer (PIXImus) was developed for mouse research; however, its use in rats is unclear. This study compared the ability of PIXImus and a standard densitometer (DPXL) to detect ovx-induced bone loss in rats both in vivo and ex vivo. Additionally, instrument accuracy was assessed by comparing measured bone mass with ash weight. Finally, the use of two distal femur regions of interest (ROI) to detect ovx-induced bone loss was evaluated. Twenty-three 6-month-old nulliparous female Sprague-Dawley rats were randomly assigned to sham or ovx groups. Distal femur bone mineral density was assessed at baseline and at 1 and 2 months postoperatively, using a PIXImus and DPXL densitometer. At 3 months postoperatively, all animals were killed, and ex vivo femur scans obtained. Distal femur bone loss was demonstrable by 1 month post-ovx using either densitometer. With the PIXImus, a 4-mm ROI demonstrated greater bone loss (p < 0.05) than an 8-mm ROI. Using the 4-mm ROI, similar amounts of bone loss were detected by the PIXImus and DPXL: 22.2% and 22.4%, respectively, at 2 months post-ovx. Total femur bone mineral content was overestimated by the PIXImus but highly correlated with the DPXL measurement (r = 0.988) and ash weight (r = 0.998). Given its comparability to standard DXA plus its rapid scan speed and portability, the PIXImus is useful in evaluating ovx-induced osteopenia in rats.
authors.affiliation: University of Wisconsin Institute on Aging, University of Wisconsin, Madison, Wisconsin 53706, USA. nbinkley@facstaff.wisc.edu
authors.forename: N
authors.initials: N
authors.lastname: Binkley
authors.forename: D B
authors.initials: DB
authors.lastname: Dahl
authors.forename: J
authors.initials: J
authors.lastname: Engelke
authors.forename: T
authors.initials: T
authors.lastname: Kawahara-Baccus
authors.forename: D
authors.initials: D
authors.lastname: Krueger
authors.forename: R J
authors.initials: RJ
authors.lastname: Colman
mesh_terms: D000818:Animals; D001835:Body Weight; D015519:Bone Density; D001851:Bone Diseases, Metabolic; D001842:Bone and Bones / Q000473:pathology*; D003720:Densitometry / Q000295:instrumentation* / Q000379:methods; D005260:Female; D005269:Femur / Q000473:pathology*; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors