FIGURE 1.

Glial cell-derived neurotrophic factor (GDNF) induces hyperalgesic priming in female and male mice. The effect of intraplantar GDNF (10 ng) or saline on mechanical sensitivity and the subsequent response to PGE₂ in male (A) and female (B) mice. 14 days after intraplantar injection of GDNF or saline, mice received an intraplantar injection of PGE₂ (100 ng/paw). The 50% paw withdrawal thresholds were monitored over time. Data are expressed as mean ± SEM. n = 8/group. (A), F = 401.03; (B), F = 300.74; DFn = 1, DFd = 280. Bonferroni’s multiple comparisons test: ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001.