involvement of nitric oxide system on anxiolytic-like behaviors induced by cholestasiss

introduction: the mechanisms of hepatic encephalopathy are not fully understood. moreover, there is no comprehensive data concerning the effects of nitric oxide (no) system on anxiolytic-like behaviors induced by bile duct ligation (bdl). methods: male mice weighing 25-30 g were used and anxiety-like behaviors were tested using hole-board task. results: the data indicated that cholestasis increased the number of head-dipping but did not alter other aspects of behavior, 7 days after bdl, suggesting an anxiolytic-like response. furthermore, the results showed that intraperitoneal (i.p.) injection of l-arginine (200 and 250 mg/kg) 15 min before testing induced anxiolytic-like behaviors in the normal animals, 4 and 7 days after bdl (considering that the dose of 200 mg in the normal mice is ineffective but is effective in the bdl mice). on the other hand, injection of l-name (35 and 45 mg/kg, i.p.) 15 min before testing induced anxiogenic-like behaviors in the normal animals, 4 and 7 days after bdl (the dose of 35 mg/kg in the normal mice is ineffective but is effective in the bdl mice ). moreover, injection of ineffective doses of l-name (25 and 35 mg/kg, i.p.) 15 min before administration of l-arginine (250 mg/kg, i.p.) and 7 days after bdl, decreased anxiolytic-like behaviors, signi.cantly. discussion: cholestatic mice show anxiolytic-like behaviors suggesting the involvement of the nitric oxide system.