Opioid mu- and kappa-receptor mediate phospholipase C activation through Gi1 in Xenopus oocytes.
In the Xenopus oocytes expressing mu- or kappa-opioid receptors, agonist-induced currents were observed only when the oocyte was coinjected with Gi1 alpha RNA and pretreated with K-252a, a potent inhibitor of protein kinases. The evoked currents were abolished by intracellular injection of EGTA or inositol 1,4,5-trisphosphate and the current-voltage relationship revealed that they are mediated through typical calcium-dependent chloride channels. These findings suggest that the mu- and kappa-receptors mediate phospholipase C activation through Gi1 alpha, and that these receptor mechanisms including downstream signalings might be inhibited by phosphorylation in vivo in the Xenopus oocyte.
D000818:Animals; D044482:Benzeneacetamides; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D004789:Enzyme Activation; D005260:Female; D019204:GTP-Binding Proteins / Q000235:genetics*; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009865:Oocytes / Q000201:enzymology*; D011759:Pyrrolidines / Q000494:pharmacology; D017473:Receptors, Opioid, kappa / Q000187:drug effects / Q000502:physiology*; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism*; D014982:Xenopus laevis
D044482:Benzeneacetamides; D004745:Enkephalins; D011759:Pyrrolidines; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C051844:norbinaltorphimine; D009271:Naltrexone; C024524:beta-funaltrexamine; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; C045444:U 69593