en Cellular and molecular Neuroscience Cellular and molecular Neuroscience Original Original <p><strong>Introduction:</strong> 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). </p><p><strong>Methods:</strong> Male mice weighing 25-30 g were used and anxiety-like behaviors were tested using hole-board task. </p><p><strong>Results:</strong> 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. </p><p><strong>Discussion:</strong> Cholestatic mice show anxiolytic-like behaviors suggesting the involvement of the nitric oxide system.</p> Cholestasis, L-Arginine, L-NAME, Anxiety, Hole-bored task, Mice. 19 29 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1-127&slc_lang=en&sid=1 Mohammad Nasehi 1370031947532846002241 1370031947532846002241 Yes Vahid Sabouri Khanghah 1370031947532846002242 1370031947532846002242 No Sepideh Mirzaei Varzeghani 1370031947532846002243 1370031947532846002243 No Mohammad-Reza Zarrindast 1370031947532846002244 1370031947532846002244 No