Effects of aging on morphine analgesia and associated changes at the µ-opioid receptor

Abstract

Event Abstract Back to Event Effects of aging on morphine analgesia and associated changes at the µ-opioid receptor Elizabeth Jeffress1*, R. Hanberry1 and A. Z. Murphy1 1 Georgia State University, Neuroscience Institute, United States Both clinical and basic science studies have established that morphine produces a differential degree of analgesia in males and females. In particular, in models of orofacial, visceral, or persistent inflammatory pain, females require 2x the amount of morphine to produce a level of analgesia comparable to males. To date, however, research on morphine analgesia has been carried out primarily in adult rats. Few studies to date have examined the effects of advanced age on morphine analgesia, and none have examined the impact of advanced age on opiate receptor expression and function. To characterize the impact of age on morphine analgesia, male and female Sprague Dawley rats (adult: 3 mos; aged 18-24 mos) received an intraplantar injection of the inflammatory agent Complete Freund’s Adjuvant (CFA) to induce persistent inflammation. Twenty-four hours later, morphine was administered using a cumulative dosing paradigm (0, 1.8, 3.2, 5.6, 8, 10, and 18 mg/kg; ip) and analgesia was assessed using the paw thermal stimulator. No significant differences were noted in baseline paw withdrawal latencies (PWLs) or in CFA-induced hyperalgesia for aged vs adult, male and female rats. A significant impact of age and sex was observed for morphine analgesia. In particular, a significant rightward shift in the morphine dose response curve was noted for aged rats, as well as adult females. ED50 values for these groups were 2x higher (7.0 mg/kg) than those for adult males (3.5 mg/kg). Subsequent anatomical studies demonstrated reduced mu opioid receptor protein and binding in the midbrain periaqueductal gray, an essential brain region for morphine action. The finding of reduced MOR levels in the PAG may provide the biological bases for the decreased morphine sensitivity observed in aged animals. Conference: 2010 South East Nerve Net (SENN) and Georgia/South Carolina Neuroscience Consortium (GASCNC) conferences, Atlanta , United States, 5 Mar - 7 Mar, 2010. Presentation Type: Poster Presentation Topic: Posters Citation: Jeffress E, Hanberry R and Murphy AZ (2010). Effects of aging on morphine analgesia and associated changes at the µ-opioid receptor. Front. Neurosci. Conference Abstract: 2010 South East Nerve Net (SENN) and Georgia/South Carolina Neuroscience Consortium (GASCNC) conferences. doi: 10.3389/conf.fnins.2010.04.00050 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Mar 2010; Published Online: 17 Mar 2010. * Correspondence: Elizabeth Jeffress, Georgia State University, Neuroscience Institute, Atlanta, United States, ejeffress1@student.gsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Elizabeth Jeffress R. Hanberry A. Z Murphy Google Elizabeth Jeffress R. Hanberry A. Z Murphy Google Scholar Elizabeth Jeffress R. Hanberry A. Z Murphy PubMed Elizabeth Jeffress R. Hanberry A. Z Murphy Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.