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Updated: Aug 14, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Periadolescent morphine exposure alters subsequent behavioral sensitivity to morphine in adult rats
David A White1, Stephen G Holtzman
1Emory University School of Medicine, Department of Pharmacology, O.W. Rollins Research Building, 1510 Clifton Road, NE, Atlanta, GA 30322, USA. dwhite4@emory.edu
Abstract:
Little research has been conducted investigating the long-term impact of opioid exposure during adolescence. These experiments were conducted to determine the behavioral effects of morphine exposure during periadolescence (postnatal days 30-32) versus young adulthood (postnatal days 65-67) on subsequent sensitivity to morphine. Male Sprague-Dawley rats were treated with three days of saline (S-S-S), one day of 10 mg/kg morphine followed by two days of saline (M-S-S), or three days of morphine (M-M-M). Unlike adult-treated counterparts, periadolescent M-M-M-treated rats showed greater locomotor response to morphine compared to S-S-S or M-S-S cohorts five weeks after treatment, suggesting age- and exposure-dependent differences in opioid sensitivity.
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