Fig. 2.

Effect of intra-habenular microinjection of morphine after intra-dorsal raphe microinjection of saline (0.5 μL/site) on corneal pain response induced by NaCl 5 M solution applied to the corneal surface in rats. Maximal possible effect (MPE%) is considered as an index for comparison between the results of two tests (for calculation of % MPE see the text). The values are expressed as mean ± SEM (n = 6 per group). The data are compared with two-way analysis of variance (ANOVA) followed by bonferroni post hoc test; ***P < 0.0001, **P < 0.001, *P < 0.01 and ^†P < 0.05 as compared to normal saline treated group. Raphe, dorsal raphe; habenula, lateral habenula.