title: Hyperalgesia and blunted morphine analgesia in G protein-gated potassium channel subunit knockout mice.
abstract: Our aim was to determine whether G protein-gated potassium (Kir3) channels contribute to thermonociception and morphine analgesia. Western blotting was used to probe for the presence of Kir3.1, Kir3.2, Kir3.3, and Kir3.4 subunits in the mouse brain and spinal cord. Hot-plate paw-lick latencies for wild-type, Kir3.2 knockout, Kir3.3 knockout, and Kir3.4 knockout mice were measured at 52 degrees C and 55 degrees C, following the s.c. injection of either saline or 10 mg/kg morphine. Paw-lick latencies for Kir3.4 knockout mice were similar to those of wild-type mice, consistent with the restricted expression pattern of Kir3.4 subunit in the mouse brain. In contrast, Kir3.2 knockout and Kir3.3 knockout mice displayed hyperalgesia at both temperatures tested, and both Kir3.2 knockout and Kir3.3 knockout mice displayed shorter paw-lick latencies following morphine administration, with Kir3.2 knockout mice exhibiting the more dramatic phenotype. Kir3.2/Kir3.3 double knockout mice displayed a greater degree of hyperalgesia than either the Kir3.2 knockout or Kir3.3 knockout mice, while performing similarly to Kir3.2 knockout mice following morphine administration. We conclude that G protein-gated potassium channels containing Kir3.2 and/or Kir3.3 play a significant role in responses to moderate thermal stimuli. Furthermore, the activation of Kir3 channels containing the Kir3.2 subunit contributes to the analgesia evoked by a moderate dose of morphine. As such, receptor-independent Kir3 channel agonists may represent a novel and selective class of analgesic agent.
authors.affiliation: Laboratory of Metabolic Diseases, The Rockefeller University, New York, NY 10021, USA.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Marker
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Cintora
authors.forename: Maria I
authors.initials: MI
authors.lastname: Roman
authors.forename: Markus
authors.initials: M
authors.lastname: Stoffel
authors.forename: Kevin
authors.initials: K
authors.lastname: Wickman
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019204:GTP-Binding Proteins / Q000378:metabolism; D006930:Hyperalgesia / Q000188:drug therapy*; D051379:Mice; D018345:Mice, Knockout; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects; D015221:Potassium Channels / Q000235:genetics*; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics
chemical_list: D000701:Analgesics, Opioid; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C497067:Kcnj3 protein, mouse; C497072:Kcnj9 protein, mouse; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D009020:Morphine; D019204:GTP-Binding Proteins