Urinary excretion of hydroxyproline and hydroxylysyl glycosides in adjuvant-induced arthritis

The effect of adjuvant-induced arthritis on the urinary excretion of hydroxyproline and hydroxylysyl glycosides (glc-gal-hyl and gal-hyl) was investigated in male Sprague-Dawley rats up to 70 days after the injection of Freund's complete adjuvant. In comparison with control animals the total urinary hydroxyproline is significantly increased in the arthritic rats at one day after injection, returns to normal level at one week and is further significantly increased between the 2nd to 7th week. The excretion of total glycosides in urine parallels the excretion of total hydroxyproline. However, the low ratio of glc-gal-hyl/gal-hyl provides circumstantial evidence in favour of the hypothesis of bone collagen degradation in the acute stage of adjuvant-induced arthritis in rats (between 2 and 3 weeks), while high absolute values but normal ratios of glc-gal-hyl/gal-hyl suggest degradation of both bone and skin collagen in equal amounts between the 4th and 7th week. No significant differences are found between control and arthritic groups in the later part of the experiment.