en Behavioral Neuroscience Behavioral Neuroscience Original Original <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Tahoma;"><span style="line-height:2;">The mesolimbic dopamine system is important in the modulation of pain and is activated under stress. Various types of stress can induce analgesia through the release of neurotransmitters and neuropeptides such as dopamine. Accordingly, the present study investigated the role of dopamine receptors in the dentate gyrus (DG) of the hippocampus in two stress models of analgesia. one hundred and thirty-three adult male rats underwent stereotaxic surgery to place a unilateral cannula into the dentate gyrus. After a one-week recovery period, separate groups of animals received different doses of the D1 receptor antagonist SCH-23390 (0.25, 1 and 4 &mu;g/0.5 &mu;l) or D2 receptor antagonist sulpiride (0.25, 1, 4 &mu;g/0.5 &mu;l) or vehicle (0.5 &mu;l DMSO or saline) into the dentate gyrus, respectively. Animals were then exposed to forced swim stress (FSS) for 6 min or restraint stress (RS) for 3 hours, and then, pain thresholds were assessed in the tail-flick test over a 60-min period. The results indicated that exposure to RS and FSS reduced pain responses in the tail-flick test, which was reduced by the inhibition of dopamine receptors. Intra-DG administration of SCH-23390 significantly reduced antinociceptive behaviors in the RS compared to the FSS. On the other hands, the effect of D2-like dopamine receptors in reducing FSS -induced analgesia was more prominent than RS.</span></span></span></div> Restraint stress, Force swimming stress, Dentate gyrus, Dopamine receptors, Tail-flick test, Rat 0 0 http://bcn.iums.ac.ir/browse.php?a_code=A-10-8558-1&slc_lang=en&sid=1 Homayoon Golmohammadi homayoongolmohammadi@yahoo.com 13700319475328460057583 13700319475328460057583 No Neuroscience Research Center, Institute of Neuroscience and Cognition, Shahid Beheshti University of Medical Science, Tehran, Iran. Mohadeseh Ghalandari-Shamami ghalandari.m@iau.ac.ir 13700319475328460057584 13700319475328460057584 No Department of Physiology, Faculty of Medical Science, TeMS.C., Islamic Azad University, Tehran, Iran. Abbas Haghparast haghparast@yahoo.com 13700319475328460057585 13700319475328460057585 Yes Neuroscience Research Center, Institute of Neuroscience and Cognition, Shahid Beheshti University of Medical Science, Tehran, Iran