Figure 5. Effect of yohimbine, propranolol, atropine and guanethidine on the antinociception caused by the administration of spironolactone (10 mg/kg. s.c.) in the acetic acid-induced writhing assay in mice. Data represent mean values of 6 mice per group (± SE) and percent inhibition (%) compared to the control animals. Statistical differences vs. control group are indicated by asterisks. The plus sign indicates significant change from yohimbine + spironolactone-treated group.