We then measured the bone-turnover markers in each group and demonstrated that the biochemical marker of osteogenic activity P1NP in the serum significantly decreased four weeks after USN, while the markers of bone resorption plasmic CTX-1 and urinary Dpd increased markedly compared to those of the sham group, indicating that osteogenic activity decreases and bone resorption increases in disuse osteoporosis, in accordance with previous studies14, 35. Here, DPYD is linked to osteoporosis.