en Neurophysiology/Pharmacology Neurophysiology/Pharmacology Experimental research article Experimental research article <strong>Introduction:</strong> The adrenergic and opioidergic systems play a crucial role in regulating cognitive and non-cognitive behaviors. The aim of this study was to evaluate the effects of CA1 &alpha;2-adrenoceptors on the exploratory behaviors induced by morphine.<br /> <strong>Methods: </strong>This assessment was conducted in rats using the elevated plus-maze test based on a test-retest paradigm. Bilateral guide cannulas were stereotaxically implanted in the CA1 regions of rats to allow intra-CA1 &alpha;2-adrenoceptors agonist (clonidine) or antagonist (yohimbine) microinjections.<br /> <strong>Results:</strong> Pre-test administration of morphine (6 mg/kg) showed an anxiolytic-like response. The extension of this effect during the retest session, 24h later, indicated impairment of aversive memory. Pre-test microinjection of clonidine (4 &micro;g/rat) induced anxiolytic-like behavior on the test day in the absence or presence of a subthreshold dose of morphine (4 mg/kg) and increased avoidance to the open-arms during the retest session, but it was not significant compared with control group. Pre-test microinjection of yohimbine (4 &micro;g/rat) induced an anxiogenic-like behavior on test day in the absence or presence of an effective dose of morphine (6mg/kg) and increased avoidance to the open-arms during the retest session. Concurrent microinjection of a subthreshold dose of yohimbine (1 &mu;g/rat) with an effective dose of clonidine or with an effective dose of clonidine plus a subthreshold dose of morphine blocked anxiolytic-like behaviors, but did not change avoidance to the open-arms.<br /> <strong>Conclusion:</strong> According to our findings, it appears that CA1 &alpha;2-adrenoceptors affect anxiolytic-like effects of morphine, but they do not appear to play a significant role in the morphine-induced memory impairment.<br /> <span style="font-size:12pt"><span style="background:white"><span style="line-height:150%"><span style="text-autospace:none"><span new="" roman="" style="font-family:" times=""><span style="font-size:9.0pt"><span style="line-height:150%"><span style="font-family:"Arial",sans-serif"></span></span></span></span></span></span></span></span> Morphine, Clonidine, Yohimbine, Anxiety, Emotional memory 66 79 http://ppj.phypha.ir/browse.php?a_code=A-10-1328-1&slc_lang=en&sid=1 Elmira Beirami elmira.beirami@khu.ac.ir 3200319475328460034178 0000000321598382 Yes Department of Animal Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran Seyedeh Masoumeh Seyedhosseini Tamijani 3200319475328460034179 3200319475328460034179 No Department of Neuroscience, School of Advanced Technologies in Medicine, Mazandaran University of Medical Sciences, Sari, Iran