Fig. 1

Experimental design. All female rats were OVx. After 10 days of recovery, E2 or oil was injected subcutaneously every 4 day. The baselines of thermal withdrawal latency (T) and mechanical withdrawal threshold (M) were tested before FS. One day before FS, bilateral masseter muscles were injected with CFA. Three day repeated FS was applied after injection of CFA. From day 2 post last FS, thermal withdrawal latency and mechanical withdrawal threshold were measured on the second and third days, respectively, after each E2/oil injection. The measurements were continued until the thermal withdrawal latency or mechanical withdrawal threshold returning to the baseline level. OVx, ovariectomized; E2, estradiol; FS, forced swim; CFA, complete Freund’s adjuvant