en Behavioral Neuroscience Behavioral Neuroscience Original Original <p><b>Introduction:</b> The plethora of studies indicated that there is a cross talk relationship between harmaline and serotonergic (5-HT) system on cognitive and non-cognitive behaviors. Thus, the purpose of this study is to assess the effects of hippocampal 5-HT4 receptor on memory acquisition deficit induced by harmaline.&nbsp;</p> <div><b>Methods:</b> Harmaline was injected peritoneally, while 5-HT4 receptor agonist (RS67333) and antagonist (RS23597-190) were injected intra-hippocampal. A single-trial step-down passive avoidance, open field and tail flick tasks were used for measurement of memory, locomotor activity and pain responses, respectively.&nbsp;</div> <div><b>Results: </b>The data revealed that pre-training injection of higher dose of harmaline (1 mg/kg), RS67333 (0.5 ng/mouse) and RS23597-190 (0.5 ng/mouse) decreased memory acquisition process in the adult mice. Moreover, concurrent pre-training administration of subthreshold dose of RS67333 (0.005 ng/mouse) or RS23597-190 (0.005 ng/mouse) with subthreshold dose of harmaline (0.5 mg/kg, i.p.) intensify impairment of memory acquisition. All above interventions did not change locomotion and tail flick behaviors.&nbsp;</div> <div><b>Discussion:</b> The results demonstrated that the synergistic effect between both hippocampal 5-HT4 receptor agonist and antagonist with impairment of memory acquisition induced by harmaline, indicating a modulatory effect for hippocampal 5HT4 receptor on Harmaline induced amnesia.</div> Memory reconsolidation, Glucocorticoids, Cholinergic agents 163 170 http://bcn.iums.ac.ir/browse.php?a_code=A-10-273-2&slc_lang=en&sid=1 Mohammad Nasehi Mo58na@yahoo.com 1370031947532846009701 1370031947532846009701 Yes Islamic Azad University, Garmsar Branch