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Updated: Aug 11, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Opioid-induced abnormal pain sensitivity
1MGH Pain Center, Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, 02114, USA. jmao@partners.org
Abstract:
Opioid analgesics are effective for treating many pain conditions. Opioid analgesic tolerance is a pharmacologic phenomenon that could affect the clinical use of opioid analgesics. Recent studies have shown that neural plasticity associated with the development of opioid tolerance may activate a pronociceptive mechanism that could counteract the analgesic effects of opioids. Thus, exposure to opioids could lead to two seemingly unrelated cellular processes (ie, the development of opioid tolerance and opioid-induced pain sensitivity). Their converging effects may be part of the mechanisms leading to the reduced opioid analgesic efficacy in chronic opioid therapy.
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