Effect of body weight on osteopenia in ovariectomized rats
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Bilateral ovariectomies or sham surgeries were performed in female Sprague Dawley rats that were 78 days of age and weighed an average of 210 g. Food was available ad libitum to the control rats and to a group of ovariectomized rats (obese OVX). The food consumption of a second group of ovariectomized rats (weight-matched OVX) was restricted to match their body weights to those of the control rats. All rats were sacrificed at 14 weeks postovariectomy. Radioimmunoassay of terminal serum estradiol confirmed the success of ovariectomy. The estradiol concentration in control rats was 24.9±20.2 pg/ml, whereas the hormone was undetectable (<10 pg/ml) in both groups of OVX rats. The final body weights of control and weight-matched OVX rats were nearly identical (∼260 g). In contrast, obese OVX rats weighed significantly more than both of the above groups (∼320 g,P<0.001). The proximal tibia and lumbar vertebra were processed undecalcified for quantitative bone histomorphometry. Tibial trabecular bone volume (TBV) was determined to be 17.6±4.5%, 7.9±5.3%, and 3.6±3.1% for the control, obese OVX, and weight-matched OVX groups, respectively. Tibial TBV for both OVX groups was significantly less than the control value (P<0.001). The difference in tibial TBV between obese OVX and weight-matched OVX rats was also statistically significant (P<0.02). Histologic indices of bone resorption and formation were indicative of increased bone turnover in the proximal tibia of both OVX groups. In comparison to control rats, both groups of OVX rats exhibited a strong trend for a reduction in vertebral TBV, but no significant differences were observed among the three groups. Our results suggest that increased body weight provides partial protection against osteopenia in the long bones of OVX rats. However, it is important to note that this protective effect is only partial and that marked osteopenia develops in the long bones of OVX rats regardless of body weight.
Key wordsQuantitative bone histomorphometry Estrogen deficiency Body weight Osteopenia Bone turnover
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- 10.Lindsay R, Dempster DW, Clemens T, Herrington BS, Wilt S (1984) Incidence, cost, and risk factors of fracture of the proximal femur in the USA. In: Christiansen C, Arnaud CD, Nordin BEC, Parfitt AM, Peck WA, Riggs BL (eds) Osteoporosis I. Glostrup Hospital, Copenhagen, p 311Google Scholar
- 11.Waynforth HB (1980) Experimental and surgical technique in the rat. Academic Press, New YorkGoogle Scholar
- 12.Baron R, Vignery A, Neff L, Silvergate A, Santa Maria A (1983) Processing of undecalcified bone specimens for bone histomorphometry. In: Recker RR (ed) Bone histomorphometry: techniques and interpretation. CRC Press, Boca Raton, Florida, p 13Google Scholar
- 14.Frost HM (1983) Bone histomorphometry: analysis of trabecular bone dynamics. In: Recker RR (ed) Bone histomorphometry: techniques and interpretation. CRC Press, Boca Raton, Florida, p 109Google Scholar
- 15.Duncan RC, Knapp RG, Miller MC (1977) Introductory biostatistics for the health sciences. John Wiley & Sons, New YorkGoogle Scholar
- 18.Draper HH, Bell RR, Shin KS (1980) Influence of adult age on the skeletal response to phosphate and estrogen in rats. J Nutr 11:778–783Google Scholar
- 19.Parfitt AM, Mathews CHE, Villanueva AR, Kleerekoper M, Frame B, Rao DS (1983) Relationships between surface, volume, and thickness of iliac trabecular bone in aging and in osteoporosis. Implications for the microanatomic and cellular mechanisms of bone loss. J Clin Invest 72:1396–1409PubMedCrossRefGoogle Scholar