Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 10 3 2016 02 06 192 199 EN Mahdieh Anoush Department of Pharmacology and Toxicology, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran Ali Jani Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Moosa Sahebgharani Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Jafari Department of Physiology and Pharmacology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran 2015 10 10 Objective: In this study, the effects of estradiol valerate and raloxifenea selective estrogen receptor modulator; (SERM) on morphine induced sensitization were examined in mice memory, according to the step-down passive avoidance task. Method:The mice received morphine or estradiol and raloxifene for three days alone or in combination with morphine. After a drug free period of 5 days, the subjects received saline or morphine as pre- training treatments followed by a pre-test saline administration. The memory retrieval was evaluated using step-down passive avoidance test both on the training and test day. Results:The results illustrated that the three- day administration of morphine induced sensitization through the enhancement of memory retrieval (morphine induced sensitization in mice memory). Both the three- day administration of estradiol valerate alone and with morphine (5 mg/kg) restored memory. On the other hand, the three- day administration of raloxifene had no effect on memory retrieval alone, but declined morphine induced sensitization in mice memory. Conclusion:The results of the study indicated that there is an interaction between estrogen receptor modulators and morphine induced sensitization in mice memory. https://ijps.tums.ac.ir/index.php/ijps/article/view/10 https://ijps.tums.ac.ir/index.php/ijps/article/download/10/8