Fig. 7.

Changes in left hind paw volume and the mechanical pain threshold (PWT) and expression of P2X3R after injection of CFA in the left hind-paw. a Two days after injection of CFA, PWT was significantly decreased compared with that of pre-injection (n = 8), while there was no differences among groups (n = 8). The decline of PWT reached a maximum on day 7 after CFA injection. The PWT of OVX rats was significantly lower than that of the sham group (n = 8), which was then reversed by estrogen replacement (n = 8). The difference was sustained until day 11 after CFA injection. *p < 0.05, compared with the sham group. b Before injection of CFA, the PWT in OVX rats was significantly decreased compared with that of sham rats (n = 8), which was then reversed by estrogen treatment (n = 8). *p < 0.01 c On the 1st day after injection of CFA, the volume of the left hind paw was increased significantly compared with that of pre-injection (n = 8). The volume of the left hind paw in estrogen-treated OVX rats was significantly decreased compared with that of OVX rats (n = 8). There was no significant difference in plantar volumes between sham and OVX rats. On days 6, 7, 9, and 11 after CFA injection, the plantar volume of estrogen-treated rats was significantly less than that of OVX rats. *p < 0.05, **p < 0.01, compared with the OVX group. d In CFA rats, the total P2X3R protein obtained from DRG isolated from OVX rats was significantly increased compared with that from sham rats (n = 6), which was then reversed by estrogen replacement for 3 weeks. *p < 0.05