Fig. 2

Estrus cycle and opto-SD-induced periorbital allodynia. Periorbital allodynia was tested either 1 h after single opto-SD (circles) or 2 days after the last day of repeated opto-SD (triangles). Vaginal smears were collected after behavior testing, (A). In multiple linear regression analysis, there was a significant effect of opto-SD (^#p < 0.0001 vs sham) and estrus cycle stage (p = 0.015) on periorbital thresholds, but no interaction between the two. Using two-way ANOVA of rank transformed data from SD and sham groups, and Sidak test for multiple comparisons, metestrus-diestrus (MD) sham females had higher periorbital thresholds (^†p = 0.029 vs PE sham females). There was no effect of estrus stage on periorbital thresholds following opto-SD as both MD and PE animals had significant reductions in mechanical thresholds following opto-SD, (B)