Fig. 1

Distribution and expression of oestrogen receptors (ERs) in the dorsal root ganglion (DRG) and spinal dorsal cord (SDH), spared nerve injury (SNI) model builded. A Immunofluorescence double labelling revealed that ERs was colocalized with IB4 (a marker of nonpeptidergic C-type neurons), CGRP (a marker of peptidergic C-type neurons), and NF-200 (a marker of A-type neurons). White arrows refer to colabelled neurons, scale bar = 50 μm. B a–c The percentage of IB4-, CGRP-, and NF-200-positive (green) neurons relative to ERs (red) positive cells. C Neuronal diameter size of IB4-, CGRP-, and NF-200-positive neurons. D Diagram of the sampling site of DRG tissue. E Double staining showing the colocalization of oestrogen receptor-α, oestrogen receptor-β, and G protein-coupled oestrogen receptor (red) with the CGRP (green) in the rat SDH. The image in the white square is the zoomed-in image of the area below the corresponding image. F Mechanical allodynia and cold hyperalgesia developed in SNI rat paws compared to Sham rats from the third day after SNI until at least day 14, thermal hyperalgesia was not significant (n = 8), Mann–Whitney U test. ^***p < 0.001, versus sham group. G Loss of CGRP(+) terminals in the SNI ipsilateral SDH (arrow), two-tailed unpaired Student’s t test. ^**p < 0.01, versus sham. H Quantification of the number of CGRP(+) terminals in sham and SNI rats (n = 6 rats). Scale bar = 200 μm. DRG dorsal root ganglion, SDH spinal dorsal horn