Sustained Morphine Exposure Induces a Spinal Dynorphin-Dependent Enhancement of Excitatory Transmitter Release from Primary Afferent Fibers

• Published in: The Journal of neuroscience Vol. 22; no. 15; pp. 6747 - 6755
• Main Authors: Gardell, Luis R, Wang, Ruizhong, Burgess, Shannon E, Ossipov, Michael H, Vanderah, Todd W, Malan, T. Philip, Jr, Lai, Josephine, Porreca, Frank
• Format: Journal Article
• Language: English
• Published: United States Soc Neuroscience 01.08.2002; Society for Neuroscience
• Subjects: Animals; Behavior, Animal - drug effects; Calcitonin Gene-Related Peptide - metabolism; Drug Implants; Drug Tolerance; Dynorphins - antagonists & inhibitors; Dynorphins - metabolism; Dynorphins - pharmacology; Hot Temperature; Hyperalgesia - chemically induced; Hyperalgesia - metabolism; Immune Sera - pharmacology; In Vitro Techniques; Male; Morphine - administration & dosage; Nerve Crush; Nerve Fibers - drug effects; Nerve Fibers - metabolism; Neuronal Plasticity - drug effects; Neurons, Afferent - drug effects; Neurons, Afferent - metabolism; Neurotransmitter Agents - metabolism; Pain Measurement - drug effects; Peptide Fragments - pharmacology; Physical Stimulation; Rats; Rats, Sprague-Dawley; Spinal Cord - drug effects; Spinal Cord - physiology; Time Factors

Paradoxical opioid-induced pain has been demonstrated repeatedly in humans and animals. The mechanisms of such pain are unknown but may relate to opioid-induced activation of descending pain facilitatory systems and enhanced expression and pronociceptive actions of spinal dynorphin. Here, the possib...