USEFULNESS OF SERUM PYRIDINOLINE CROSS-LINKED CARBOXY-TERMINAL TELOPEPTIDES OF TYPE-I COLLAGEN AND OSTEOCALCIN IN THE STUDY OF THE BONE-RESORPTION RATE IN OOPHORECTOMIZED RATS

The aim of this work was to determine sensitivity and specificity of s erum pyridinoline cross-linked carboxy-terminal telopeptides of type I collagen (ICTP), a new biochemical marker of bone resorption, in orde r to study the rate of bone resorption associated with osteopenia deve lopment after oophorectomy in rats. The diagnostic accuracy of the bon e formation marker osteocalcin (BGP) was also evaluated. Twelve-week-o ld female Wistar rats were used: (1) control group: sham-operated, tre ated with a placebo (n = 25); (2) OOX: oophorectomized rats treated wi th a placebo (n = 12), and (3) OE: oophorectomized rats treated with 1 7 alpha-ethinyl estradiol 0.1 mg/kg/day for 3 months. The rats were sa crificed after treatment, and lumbar bone mineral density, BGP, and IC TP (serum assays specific for rat) were determined. As expected, OOX a nimals developed osteopenia. OOX rats showed a significant decrease (p < 0.05) in bone mineral density as compared with the control group, a nd OE rats showed no significant differences with respect to the contr ol group. With respect to biochemical markers of bone remodeling, the OOX group showed a significant increase in BGP and ICTP (p < 0.005 and p < 0.05, respectively) with respect to control rats. However, the va lues of BGP and ICTP were similar in the OE group and in control anima ls. Areas under receiver operation characteristic curves corresponding to BGP and ICTP were 95 and 87%, respectively (p = 0.523). The result s of the present work show that BGP and ICTP, the new resorption assay developed for rats, are reliable markers to be used in the study and follow-up of bone remodeling in OOX rats.