Fig. 5

Diagrams showing c-Fos immunoreactive cells across different levels of TNC (mean + SEM) in the whole dorsal horn a, c and the V/1 area b, d 2.5 h after IS a, b, c, d or SIF c, d. Representative photomicrographs showing c-Fos IR cells in the dorsal horns of 2IS e, f, 2SIF groups g, h. Green highlighting shows the V/1 area in the dorsal horn. Scale bar: 200 μm. We found significant difference between right and left side of the dorsal horn laminae I-II a, and the ventral part of the dorsal horn b. IS caused significant difference in the number of c-Fos positive cells in the V/1 area d. Peak at obex follows the activation pattern of FRE, substantial peak at obex (− 6) - (− 8) mm is consistent with the increased number of cells found in NAT group (*p < 0.05, #p < 0.01, $p < 0.001)