Changes in bone mineral content of calcium (Ca), phosphorous (P), magnesium and potassium for male and female Wistar rats during their development from 3 weeks old to adulthood (27 weeks old) were measured. Bone mineral content was related to areal bone mineral density (BMD) which was measured in vivo at the femoral neck using a calibrated X-ray transmission system to obtain basal curves as a function of the age of the specimen. Diagnostic curves were built to determine low BMD (osteopaenia) and osteoporosis in female rats fed a Ca-depleted diet (50%) based on the obtained data and the criteria established by the World Health Organization. Bone mineral content is directly related to sex and age, but P did not change throughout the experimental period. P content did not exhibit significant changes with growing, while Ca was greatest in male rats, producing significant differences in the Ca:P ratio. Male rats reach the Ca:P ratio peak before female rats. However, areal BMD does not follow the same trend. On the other hand, osteoporosis produced a 45% decrease in this parameter for young and mature adults. These results make Z-score values available to diagnose bone-mass losses and hence the possibility of improving the conditions of non-contact measurement of BMD in vivo. This technique can be used for future experiments with Wistar rats.
Keywords: Areal bone mineral density curve (aBMD); Z-score rats; bone mineral content; osteoporosis model; single X-ray transmission.