Papers of the Week

The leukotrienes are inflammatory mediators. In the present study, the analgesic role of local montelukast, a cysteinyl leukotriene receptor antagonist, and the possible involvement of L-arginine/NO/cGMP/K channel pathway and PPARγ receptors was assessed in the formalin test in rats. The local administration of montelukast into the hind paw produced dose-related analgesia during both phases of formalin test. Furthermore, pre-treatment with L-NAME, methylene blue, and glibenclamide prevented montelukast (10 μg/paw)-induced antinociception in both early and late phases of the test. Moreover, the local L-arginine and diazoxide before the sub-effective dose of montelukast (3 μg/paw) produced an analgesic effect. Also, local GW-9662 blocked antinociception induced by montelukast plus pioglitazone (10 μg/paw). In conclusion, montelukast produced a peripheral analgesia through PPARγ receptors and activation of the L-arginine/NO/cGMP/K channel pathway, with potential for a new topical analgesic drug.