modulation of anxiety-like behavior in sildenafil citrate-treated mice placed in an elevated plus-maze

introduction: sildenafil, a phosphodiesterase-5 (pde5) inhibitor, may have various effects on the central nervous system via the nitric oxide (no)-cyclic guanosine monophosphate (cgmp) pathway. preclinical studies have shown the controversial effect of sildenafil on anxiety-like behavior in animals. this study was undertaken to investigate the acute effect of sildenafil on anxiety-like behavior in mice. methods: male mice were intraperitoneally (i.p.) administrated sildenafil (1, 2, or 10 mg/kg), and the control group was given the vehicle 15 min before the plus-maze test. the number of entries into the open arms of the plus-maze, the time spent in the open arms, and the total numbers of entries into the arms were recorded. results: the results indicated that compared to the control group, the sildenafil-treated mice spent more time in the open arms and had a greater number of entries into open arms. the total number of entries into the arms did not significantly differ between the sildenafil-treated groups and the control group. discussion: acute administration of sildenafil could have anxiolytic effects on male mice. this effect might be mediated in a time-dependent manner by the no/ cgmp/pde5 pathway.