Fig. 3

The change and distribution of cannabinoid receptors and HCN channels in the PAG of CM rats. A Representative western blots of CGRP. B The level of CGRP expression was substantially increased in the CM group compared to that in the Sham group. (n = 6/group, **p < 0.01). C The mRNA expression of CB1R in the CM group was markedly higher than that in the Sham group. The mRNA expression of CB2R was not markedly different between the CM and Sham groups; (n = 6/group, **p < 0.01, N, S, not significant). D The mRNA levels of HCN1 and HCN2 were substantially higher in the CM group than those in the Sham group. No change was found at the mRNA levels of HCN3 and HCN4 between the Sham and CM groups. (n = 6/group, **p < 0.01, N, S, not significant). E Representative western blots of CB1R and HCN2. F-G Compared with the Sham group, the protein levels of CB1R and HCN2 in the CM group were drastically increased. H Double immunofluorescence labeling of CB1R (green) and NeuN (red). In the PAG, almost all CB1R was expressed in neurons (as shown by the white arrow). (scale bar = 20 μm). I Double immunofluorescence labeling of HCN2 (green) and NeuN (red). HCN2 was found to be clearly expressed in neurons of the PAG (as shown by the white arrow). (scale bar = 20 μm). J Double immunofluorescence labeling of HCN2 (green) and CB1R (red) revealed that CB1R was coexpressed with HCN2 (as shown by the white arrow). (scale bar = 20 μm)