RT Journal Article
SR Electronic
T1 Opioids Binding <em>Mu</em> and <em>Delta</em>Receptors Exhibit Diverse Efficacy in the Activation of G<sub>i2</sub>and G<sub>x/z</sub> Transducer Proteins in Mouse Periaqueductal Gray Matter
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 549
OP 557
VO 281
IS 1
A1 Garzón, Javier
A1 García-España, Antonio
A1 Sánchez-Blázquez, Pilar
YR 1997
UL http://jpet.aspetjournals.org/content/281/1/549.abstract
AB A nonisotopic, immunoelectrophoretic technique was used to analyze the characteristics of opioid-evoked activation of Gi2/Gx/z transducer proteins of mouse periaqueductal gray matter membranes. In the presence of picomolar concentrations of guanosine 5′-O-(3-thiotriphosphate), the opioid agonists promoted concentration-dependent increases of immunoreactivity associated with free Gi2α and Gx/zα subunits. [d-Ala2,N-MePhe4,Gly-ol5]enkephalin and morphine (preferential agonists at mu opioid receptors) and β-endorphin-(1–31) (an agonist atmu/delta opioid receptors) activated Gx/zproteins. In contrast, the agonists of delta opioid receptors, [d-Ala2]deltorphin II and [d-Pen2,5]enkephalin, displayed little or no activity on this pertussis toxin resistant regulatory protein. Although exhibiting diverse efficacy, all the opioids studied activated Gi2 transducer proteins. [d-Ala2,N-MePhe4,Gly-ol5]enkephalin and [d-Ala2]deltorphin II were more potent at Gi2α subunits than at Gx/zα subunits. The opioid antagonist naloxone displayed a competitive profile in reducing the activation of G proteins promoted by morphine. Moreover, [d-Pen2,5]enkephalin antagonized the releasing effect exerted by [d-Ala2]deltorphin II on Gi2α and Gx/zα subunits.N,N-diallyl-Tyr-Aib-Aib-Phe-Leu (ICI-174864) reduced the Gα-related immunosignals promoted by agonists of delta opioid receptors. Therefore, it is suggested that opioids exhibit marked differences in efficacy and/or potency in the activation of Gi2 and Gx/ztransducer proteins in mouse periaqueductal gray matter. The American Society for Pharmacology and Experimental Therapeutics