Fig. 8. The effect of the pretreatment of the MK-801 on increase in dynorphin-induced signal intensity (A : cingulate cortex (CG); B : somatosensory cortex (S1); C : insula cortex (IC); D : medial thalamic region (mTH); E : lateral thalamic region (lTH)). Data are expressed as percentages of the corresponding baseline levels with mean ± SEM for five mice. Bonferroni test: **P < 0.01, ***P < 0.001, the basal intensity of saline-pretreated groups versus  dynorphin challenge in saline-pretreated groups; $ P < 0.05, $$ P < 0.01, $$$ P < 0.001, the dynorphin challenge in saline-pretreated groups versus  dynorphin challenge in MK-801-pretreated groups.