Masseter muscle activity following capsaicin application to M2 in the rats with M1 CFA-applied or saline-applied rats.

<p>Typical examples of EMG activities recorded from the masseter muscle following capsaicin application to M2 in the rats with saline (A) or CFA (Ba: large response, Bb: small response) application to M1 on day 3 after the treatments. C and D: The mean area under the curve of integrated EMG following capsaicin application to M2 in M1 CFA- or saline-applied rats (C), and that following Veh- or PD98059-administration in the rats with M1 CFA application (D). E and F: Low (E) and high (F) magnification photomicrographs of CFA-applied M1 sections. G: High magnification photomicrograph of the area inidicated by the square box with the solid arrow in E. The open arrow in A indicates the timing of capsaicin application to M2. Open arrows in D and E indicate the apex of M1. The inset diagrams in A and D indicate the tooth pulp with drug application in this and following figures. CFA: complete Freund’s adjuvant, pre: before capsaicin application, post-capsaicin: after capsaicin application. +, # : p<0.05, ##: p<0.01.</p

GFAP-IR cells in TG following capsaicin application to M2 in M1 CFA- or saline-applied rats.

<p>A, B and C: GFAP-IR cells in naïve (A), M1 saline (B) or CFA-applied (C) rats. D: Photomicrograph of GFAP-IR cells (D), FG(+) cells (E) and FG(+) GFAP-IR cells (F) in TG. G: The mean relative number of TG neurons encircled with GFAP-IR cells (%). H: The mean relative number of FG(+) TG neurons encircled with GFAP-IR cells in FG(+) cells (%). I: The mean relative number of FG(–) TG neurons encircled with GFAP-IR cells in FG(–) cells (%). The open arrow heads indicate GFAP-IR cells. The white arrow heads indicate FG(+) cells encircled with GFAP-IR cells. *: p<0.05, **: p<0.01.</p

Photomicrographs and percentage of double retrograde tracing from M1 and M2 afferents to TG neurons.

<p>A, B and C: Low magnification photomicrographs of FG(+) TG cells at 3 days after FG application to M1 (A) and DiI application to M2 (B), and the photomicrograph of A merged with B (C). D, E and F: High magnification photomicrographs of FG(+) TG cells 3 days after FG application to M1 (D) and DiI application to M2 (E), and the photomicrograph of E merged with F (F). Ga: Percentage of FG and DiI double-labeled TG cells indicated by the yellow pie. White arrow heads indicate FG and DiI double-labeled TG cells, the white arrows are FG(+) TG cells and open arrow heads are DiI(+) TG cells.</p

Effect of FC injection into TG on masseter muscle activity and GFAP and pERK-IR cell expression.

<p>A and B: Typical example of masseter muscle EMG activities following capsaicin application to M2 in M1 CFA-applied rats with Veh (A) or FC (B) injection to TG. C: The mean area under the curve of integrated EMG following capsaicin application to M2 in M1 CFA-applied rats with Veh or FC-injection to TG (C). D and E: Photomicrographs of GFAP-IR cells in TG Veh-injected rats (D) and TG FC-injected rats (E). F: The mean relative number (%) of TG cells encircled with GFAP-IR cells following Veh- (solid bur) or FC- (open bur) administration in M1 CFA rats. G and H: Photomicrographs of pERK-IR cells following M2 capsaicin application in TG Veh- (G) and TG FC-injected rats (H). I: The mean relative number (%) of pERK-IR cells in TG following M2 capsaicin application in TG Veh- and TG FC-injected rats which received CFA in M1. Solid arrow in A indicates the timing of capsaicin application. White arrow heads in D and E indicate GFAP-IR cells and those in G and H are pERK-IR cells, respectively. Veh: vehicle for FC, FC: Fluorocitrate. #: p<0.05, +++: p<0.001, *: p<0.05, **: p<0.01.</p

FG-labeled TG cells and pERK-IR TG cells following capsaicin application to M2 in M1 CFA- or saline-applied rats.

<p>Fluorescent photomicrographs of FG(+) cells (A and D), pERK-IR cells (B and E) and FG merged with pERK-IR (C and F) in TG (M1 saline-applied rats: A, B and C; M1CFA-inected rats: D, E and F ). G and H: The mean percentages of FG (+) pERK-IR cells/FG (+) cells (G) and mean percentage of FG(–) pERK-IR cells/FG (–) cells (H). I: The photomicrograph of FG-applied M1 sections. FG can be seen as blue-stained product in M1. The solid arrow heads indicate FG(+) pERK-IR cells in A-F. The open arrow heads indicate FG(+) cells in D and F. The arrows indicate pERK-IR cells in B, C, E and F. The large white arrow in I indicates the apex of M1. The white star in I indicates coronal pulp cavity. * : p<0.05.</p

Effect of PD98059 administration on GFAP and Iba1 immunoreactivities in ION-CCI rats.

<p>A and B: Photomicrographs of GFAP-IR cells in Vc in ION-CCI rats with i.t. PD98059 (A) or vehicle (B) administration. C and D: Photomicrographs of Iba1-IR cells in Vc in ION-CCI rats with i.t. PD98059(C) or vehicle (D) administration. E and F: Mean areas occupied by GFAP-IR (E) and Iba1-IR (F) immuno-products in ION-CCI rats with i.t. vehicle or PD98059 administration.</p

Single neuronal activity of Vc WDR neurons in ION-CCI and sham rats.

<p>A: Mean background activities. B: Mean afterdischarges. C: Mean spike frequency following graded mechanical stimuli. D: Mean spikes following brushing to the RF. E: Mean spikes following pinching to the RF. F: Mean spike frequency following graded heat stimuli. G: Mean spike frequency following graded cold stimuli. *: p<0.05 (sham vs. ION-CCI), **: p<0.01 (sham vs. ION-CCI).</p

Effect of i.t. administration of PD98059 on Vc WDR neuronal activities in ION-CCI rats.

<p>A: Mean background activities. B: Mean afterdischarges. C: Mean spike frequency following graded mechanical stimuli. D: Mean spikes following brushing the RF. E: Mean spikes following pinching the RF. F: Mean spike frequency following graded heat stimuli. G: Mean spike frequency following graded cold stimuli. *: p<0.05, **: p<0.01 (vehicle vs. PD98059).</p

Rostro-caudal distribution and mean number of pERK-IR cells.

<p>A and B: rostro-caudal distribution of pERK-IR cells following 6 g (A) and 60 g (B) mechanical stimulation of the whisker pad skin in sham rats. C and D: rostro-caudal distribution of pERK-IR cells following 6 g (C) and 60 g (D) mechanical stimulation of the whisker pad skin in ION-CCI rats. E: Mean number of pERK-IR cells following 6 or 60 g stimulation of the whisker pad skin in naïve, sham and ION-CCI rats. **: p<0.001 (sham vs. ION-CCI).</p

Nocifensive behavior to mechanical, heat or cold stimulation of the whisker pad skin in sham and ION-CCI rats.

<p>Time-course change in the head-withdrawal threshold to mechanical stimulation of the whisker pad skin (A), head-withdrawal latency to heat stimulation of the whisker pad skin (B) and face scratching frequency following acetone application to the whisker pad skin (C). Ipsi. to CCI: ipsilateral side to CCI, Contra. to CCI: contralateral side to CCI, Ipsi. to sham: ipsilateral side to sham operation, before: before ION-CCI or sham operation. *: p<0.05 (vs. before), **: p<0.01 (vs. before).</p