Papers of the Week

Opioid signaling can occur through several downstream mediators and influence analgesia as well as reward mechanisms in the nervous system. K channels are downstream targets of the μ opioid receptor and contribute to morphine-induced antinociception. The aim of the present work was to assess the role of SUR1-subtype K channels in antinociception and hyperlocomotion of synthetic and semi-synthetic opioids. Adult male and female mice wild-type (WT) and SUR1 deficient (KO) mice were assessed for mechanical and thermal antinociception after administration of either buprenorphine, fentanyl, or DAMGO. Potassium flux was assessed in the dorsal root ganglia and superficial dorsal horn cells in WT and KO mice. Hyperlocomotion was also assessed in WT and KO animals after buprenorphine, fentanyl, or DAMGO administration. SUR1 KO mice had attenuated mechanical antinociception after systemic administration of buprenorphine, fentanyl, and DAMGO. Potassium flux was also attenuated in the dorsal root ganglia and spinal cord dorsal horn cells after acute administration of buprenorphine and fentanyl. Hyperlocomotion after administration of morphine and buprenorphine was potentiated in SUR1 KO mice, but was not seen after administration of fentanyl or DAMGO. These results suggest SUR1-subtype K channels mediate the antinociceptive response of several classes of opioids (alkaloid and synthetic/semi-synthetic), but may not contribute to the "drug-seeking" behaviors of all classes of opioids.