Determination of oxytetracycline induced fluorescence and autofluorescence as an indicator of age and sex differences in rat femur.

Simple and rapid methods for the determination and detection of autofluorescence and oxytetracycline (OTC) induced fluorescence in powdered and intact bone (without previous chemical extraction of the antibiotic) were used to estimate age and sex related differences in the rat femur. The autofluorescence always had collagen characteristics; it increased with age and was not sex dependent. The intensity of OTC induced fluorescence decreased with age, being higher in males than in females. In the oldest animals, however a slight increase in the fluorescence intensity was observed, and sex differences disappeared. The spectrofluorometric measurements of intact femora indicate a higher OTC retention on the bone surface of young animals and adult males but not in adult females. The results indicate that the determination of OTC retention in the bone using our quantitative fluorometric method and the detection of OTC deposition at bone surface using a spectrofluorometric technique can be a sensitive and inexpensive tool for experimental studies of bone changes in physiological and pathological conditions.