Figure 2.
Formalin-induced amygdala ERK activation. a, Representative Western blots for phospho-ERK (top) and total-ERK (bottom) 3 h after formalin or saline paw injection. b, Densitometry analysis of bands corresponding to ERK1 (p44) and ERK2 (p42) show that ERK2 activation in the amygdala of formalin-injected animals is significantly greater than in saline-injected animals 3 h, but not 3 min or 25 min after formalin injection (n = 10 animals per treatment per time point; *p < 0.05, two-way ANOVA, Bonferroni's post hoc test). No significant ERK1 activation was observed. c, Anatomical distribution of formalin-induced ERK activation in the amygdala. Immunohistochemistry for phospho-ERK on coronal brain sections taken from animals 3 h after saline (top) or formalin (bottom) injection in the hindpaw. Formalin-induced ERK activation is localized to the laterocapsular subdivision of the central nucleus of the amygdala. Magnified views of the area delineated by the box are shown in the right panel. CeL, Lateral subdivision of central nucleus; CeC, capsular subdivision of central nucleus; CeM, medial subdivision of central nucleus; BLA, basolateral nucleus. Error bars indicate SEM.