The aged male rat as a model for human osteoporosis: evaluation by nondestructive measurements and biomechanical testing.
Effects of androgen deficiency and androgen replacement on bone density, as measured with dual-energy X-ray absorptiometry (DXA) and single photon absorptiometry (SPA), cortical ratio (cortical thickness/outside bone diameter x 100), and biomechanical properties were evaluated in 14-month-old (1 month after orchiectomy (orch) or sham-operation) and in 17-month-old (4 months after orch or sham) male rats. Whole femoral bone mineral content (BMC) and density (BMD) measured with DXA were not significantly decreased 1 month after orch. Whole femoral BMC and BMD were 10% and 8% lower in 4 months after orch (P < 0.01 and P < 0.001, respectively). This decrease was prevented by testosterone replacement. There was an excellent correlation (R = 0.99) between whole femoral BMC and femoral ash weight. Selective scanning of cortical and cancellous sites of the femur showed that both cancellous and cortical BMC and BMD were significantly decreased 4 months after orch. SPA of the right tibia confirmed a 7% decrease in cancellous BMC and BMD 4 months after orch (preventable by testosterone) but not in cortical BMD and BMC. Femoral cortical ratio decreased with age (47 +/- 2 in 14-month-old and 40 +/- 2 in 17-month-old sham rats versus 63 +/- 1 in 6-month-old male rats) due to a continuously enlarging femoral shaft. Androgen deficiency resulted in an even greater decrease of the cortical ratio 4 months after orch (36 +/- 2 in 17-month-old orch rats) that was again prevented by testosterone (47 +/- 3).(ABSTRACT TRUNCATED AT 250 WORDS)
Vanderschueren
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Laboratorium voor Experimentele Geneeskunde en Endocrinologie, Katholieke Universiteit Leuven, Belgium.
Van Herck
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Schot
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Rush
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Einhorn
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Geusens
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Bouillon
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R
D015502:Absorptiometry, Photon; D000375:Aging / Q000502:physiology*; D000728:Androgens / Q000172:deficiency* / Q000627:therapeutic use; D000818:Animals; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D004195:Disease Models, Animal; D005269:Femur; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013977:Tibia
D000728:Androgens