Rewarding Effects of MOR Agonists in Presence of Pain – UROP Symposium

Rewarding Effects of MOR Agonists in Presence of Pain

Anjelika Varma

Research Mentor(s): Emily Jutkiewicz
Research Mentor School/College/Department: Pharmacology Department
Presentation Date: 08/03/2022
Presentation Type: Poster
Poster Number: 41
Session: Session I: 12:30 – 1:20pm
Room: League Ballroom
Authors: Emily Jutkiewicz, PhD



In the United States alone, roughly 10% of patients prescribed an opioid for pain management develop a habit of misuse. At this time, it is unclear whether or not pain itself alters the abuse liability of opioid analgesics, specifically mu-opioid receptor (MOR) agonists. The goal of this project is to evaluate the rewarding effects of MOR agonists in the presence or absence of pain in mice. We hypothesize that morphine would block the aversive effects produced by injection of dilute acetic acid at doses that did not produce conditioned place preference on its own. In order to evaluate this hypothesis, male C57BL/6N mice were placed into apparatus with two distinct environments separated by a small door, and we evaluated any potential environment bias over two 30-min bias tests. Following bias testing, mice underwent two conditioning sessions, in which mice received saline in one environment and morphine with or without a noxious stimulus (0.6% acetic acid) in the other environment. Following one day conditioning, side preferences were measured by time spent in each environment during a 30-min test in which mice had access to both chambers. In the first group tested, 10 mg/kg morphine was administered resulting in the time spent in the drug-administered side increasing compared to pre-conditioning time. In the second group tested, 0.1 mg/kg was administered resulting in a minor increase in time spent in the drug-administered side. The data collected indicates that a dosage of 0.1 mg/kg morphine is more effective at alleviating pain while simultaneously limiting the rewarding effect of MOR agonists.


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