Related Experiment Video
Updated: Jun 24, 2025

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Morphine acts in vitro to directly prime nociceptors
Eugen V Khomula1, Jon D Levine1,2
1Department of Oral & Maxillofacial Surgery, University of California at San Francisco, San Francisco, CA, USA.
None:
Hyperalgesic priming is a preclinical model of the transition from acute to chronic pain characterized by a leftward shift in the dose-response curve for and marked prolongation of prostaglandin E2 (PGE2)-induced mechanical hyperalgesia, in vivo. In vitro, priming in nociceptors is characterized by a leftward shift in the concentration dependence for PGE2-induced nociceptor sensitization. In the present in vitro study we tested the hypothesis that a mu-opioid receptor (MOR) agonist opioid analgesic, morphine, can produce priming by its direct action on nociceptors. We report that treatment of nociceptors with morphine, in vitro, produces a leftward shift in the concentration dependence for PGE2-induced nociceptor sensitization. Our findings support the suggestion that opioids act directly on nociceptors to induce priming.
Related Concept Videos
Analgesia and Pain Management
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Opioid Receptors: Overview
Opioid Analgesics: Morphine and Other Natural Cogeners
Nociception
Pain

