Figure 2. NPY and Y1R were upregulated in subchondral cancellous bone of OP patients and OVX rats. Immunohistochemical analysis of bone tissue between OA and OP group (A), and between SHAM and OVX group (C) for NPY and Y1R (x 400). Correlation between BV/TV and the expression of NPY and Y1R in OP group (B) and OVX group (D). The data are expressed as the means ± SD. r=correlation coefficient assessed by Pearson correlation analysis. **P<0.01; ***P<0.001; ****P<0.0001 by the unpaired two-tailed Student’s t-test.