Opioid Actions in Primary-Afferent Fibers—Involvement in Analgesia and Anesthesia

• Main Authors: Tsugumi Fujita, Kotaro Mizuta, Eiichi Kumamoto
• Format: Article
• Language: English
• Published: MDPI AG 2011-01-01
• Series: Pharmaceuticals
• Subjects: opioids; spinal dorsal horn; excitatory synaptic transmission; primary-afferent fiber; action potential conduction
• Online Access: http://www.mdpi.com/1424-8247/4/2/343/

Opioids inhibit glutamatergic excitatory transmission from the periphery by activating G-protein coupled opioid receptors in the central terminals of primary-afferent neurons in the spinal substantia gelatinosa, resulting in antinociception. Opioid receptor activation in the peripheral terminals of primary-afferent neurons inhibits the production of action potentials in response to nociceptive stimuli given to the periphery, leading to antinociception. Opioids also exhibit a local anesthetic effect without opioid receptor activation in peripheral nerve fibers. This review article will focus on analgesia and anesthesia produced by the actions of opioids on primary-afferent fibers.