Morphometry and calcium contents in appendicular and axial bones of exercised ovariectomized rats

Abstract

To determine the effects of exercise and ovariectomy on calcium status in selected appendicular and axial bones, female Sprague-Dawley (8-9 mo) rats were assigned to groups based on the following combinations: control (C) or ovariectomized (O); sedentary (S) or exercised (E); and length of treatment (2 or 4 mo). Exercise consisted of treadmill running for 1 h/day, 5 days/wk at a speed of 14.1 m/min and 8 degrees elevation. After death, femurs, tibia-fibula complexes, ribs (T7), and vertebrae (T7) were excised, cleaned, and weighed, and selected morphometrics were measured. Tensile strength was measured for the femurs, and all bones were then acid-hydrolyzed and calcium concentration determined spectrophotometrically. Bone [Ca2+] was significantly greater for CE and OE animals when compared with their sedentary counterparts (CS, OS). Within 4 mo calcium losses were evident in the femur and tibia of the ovariectomized animals, and the moderate exercise program was of insufficient intensity to alter this loss. The average stress to failure for femur from all groups was 1.13 +/- 0.11 N/m2. However, the effects of exercise appeared beneficial in the axial bones where [Ca2+] increased in the ovariectomized animals.

The Effect of Low Calcium Diet on Bone in Ovariectomized Mice.

“…Differences in Ca ingestion may arise from Ca intake in the intestine or kinds food. Vitamin D intake that influences Ca absorption in the intestine [11][12][13] , hormones unbalance by aging 2) and suppression of decline in Ca absorption in the intestine by exercise 14,15) are significant factors for this. Ca intake maintains bone mass and inhibits bone loss and decreases risk of fracture.…”

Influence of Aging on Cortical and Trabecular Bone Response to Estradiol Treatment in Ovariectomized Rats

“…Perhaps the greater mechanical forces exerted on the distal diaphysis compared to the mid-femoral diaphysis provide some protection against cortical bone loss in ovariectomized rats [41]. Moreover, the role of mechanical loading independent of gonadal steroids has been demonstrated for cortical bone [42] in ovariectomized rats. Regardless of previous mechanical functions, immobilization is potentially a greater threat to bone strength and mechanical competence than the absence of gonadal hormones.…”

Ação do ultra-som de baixa intensidade em ossos de ratas osteopênicas.

“…Entretanto, osso cortical não é muito sensível para perda óssea após ovarectomia, corroborando com maior perda de osso trabecular que cortical em mulheres pós-menopausais (KALU, 1991). POHLMAN et al (1985) observaram, ao avaliar a força da diáfise femural através de ensaio mecânico, que as ratas embora osteopênicas não apresentaram diferenças significativas na força máxima da região cortical q uando comparadas com grupo controle. Portanto, também confirmando a menor diminuição de osso cortical após ovarectomia.…”