The antinociceptive effect of 1‐(2‐trifluoromethylphenyl) imidazole (TRIM), a potent inhibitor of neuronal nitric oxide synthase in vitro, in the mouse

1-(2-trifluoromethylphenyl)imidazole (TRIM) is a potent inhibitor of neuronal (mouse cerebellar) and inducible (lung from endotoxin-pretreated rats) isoforms of nitric oxide synthase (NOS) with IC50 values of 28.2 microM and 27.0 microM, respectively. In contrast, TRIM is a poor inhibitor of bovine aortic endothelial NOS with an IC50 of 1057.5 microM. TRIM (10-50 mg kg-1) administered i.p. exhibits dose-related antinociceptive activity in the mouse (assessed as inhibition of late phase formalin-induced hindpaw licking behaviour) with an ED50 of 85.8 mumol kg-1. In contrast, TRIM (50 mg kg-1, i.p.) failed to influence mean arterial blood pressure in the urethane-anaesthetized mouse. Thus, TRIM may be of use as an experimental tool with which to investigate the biological roles of nitric oxide (NO) within the central nervous system.