Loss of SUR1 subtype KATP channels alters antinociception and locomotor activity after opioid administration
BackgroundOpioid signaling can occur through several downstream mediators and influence analgesia as well as reward mechanisms in the nervous system. KATP channels are downstream targets of the opioid receptor and contribute to morphine-induced antinociception. AimsThe aim of the present work was to assess the role of SUR1-subtype KATP channels in antinocicpetion and hyperlocomotion of synthetic and semi-synthetic opioids. MethodsAdult 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. ResultsSUR1 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 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. ConclusionsThese results suggest SUR1-subtype KATP 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.