en Neurosciences Neurosciences Original Article Original Article <p><span style="font-family:Tahoma;"><span style="font-size:12px;"><span style="line-height:200%"><span style="unicode-bidi:embed"><span style="line-height:200%">The aim of the present study was to examine the hypothesis that miR-33-5p attenuates morphine state-dependent (StD) memory via the &micro; opioid receptor by regulating cyclic AMP response element-binding protein (CREB). The effects of post-training morphine and morphine StD memory and their interaction with pre-test naloxone were evaluated using a single-trial inhibitory avoidance paradigm. Then, the hippocampal miR-33-5p gene and pCREB/CREB protein expression profiles were evaluated using quantitative real-time PCR and western blotting, respectively. We found that while post-training morphine and morphine StD memory respectively up- and down-regulate the miR-33-5p expression profile in the hippocampus, the reverse results are true for the expression of pCREB/CREB. Pre-test naloxone antagonized the response. Overall, our findings suggest that the expression levels of miR-33-5p in the hippocampus set the basis for morphine StD memory with low miR-33-5p enabling state dependency. The mechanism is mediated via miR33-5p and CREB signaling with the interaction of the &micro; opioid receptor. This finding may be used as a potential strategy for ameliorating morphine-induced memory-related disorders.</span></span></span></span></span></p> miR-33-5p, CREB, state-dependent memory, opioids, rats 150 167 http://ijmcmed.org/browse.php?a_code=A-10-4948-1&slc_lang=en&sid=1 Sadegh Moradi-Vastegani smv6020@yahoo.com 100319475328460026161 100319475328460026161 No Institute for Basic Sciences, Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran. Behrang Alani behrangha@yahoo.com 100319475328460026162 100319475328460026162 No Department of Applied Cell Sciences, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran. Khatereh Kharazmi kharazmee.kh@gmail.com 100319475328460026163 100319475328460026163 No Institute for Basic Sciences, Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran. Abolfazl Ardjmand ardjmand_ab@kaums.ac.ir 100319475328460026164 100319475328460026164 Yes Institute for Basic Sciences, Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran.