Figure 2 :Effect of i.c.v. injection of chlorpheniramine on the numbers of writhes induced by acetic acid in rats. Each column represents mean ± SEM (n = 6 rats for normal saline, six rats for chlorpheniramine and six rats for ranitidine). *P < 0.05 vs. normal saline (one-way ANOVA followed by Duncan's test), i.c.v.: intracerebroventricular.