[Characterization of adrenal medullary opioid receptors. II. Coupling of adrenal medullary opioid receptors to GTP binding proteins].
We studied possible coupling of opioid receptors to GTP-binding proteins to clarify the mechanism(s) of opioid action in bovine adrenal medullary membranes. Guanylyl imidodiphosphate (Gpp(NH)p) reduced the binding of [3H] D-Ala2-D-Leu5-enkephalin ([3H] DADLE) to bovine adrenal medullary membranes dose-dependently, and enhanced the binding of [3H] diprenorphine to them. Gpp(NH)p (0.1 mM) enhanced the Kd value of the [3H] DADLE binding from 2.9 nM to 3.9 nM, but did not change its Bmax. Pretreatment of bovine adrenal medullary membranes with pertussis toxin (PT) reduced the [3H] DADLE binding. The Gpp(NH)p inhibition for [3H] DADLE binding was diminished by the PT-pretreatment. On the other hand, the [3H] diprenorphine binding to PT-pretreated membranes was higher than that to control membranes. Levorphanol inhibited the adenylate cyclase activity of the rat caudate nucleus crude synaptosomal fraction, but did not change that of bovine adrenal medullary membranes. These results suggest that opioid receptors in bovine adrenal medullary membranes are coupled to PT-sensitive GTP-binding protein which may not influence on adenylate cyclase.
Murase
H
H
Third Department of Internal Medicine, Gifu University School of Medicine, Japan.
Kamikubo
K
K
Murayama
M
M
Yasuda
K
K
Tsurumi
K
K
Miura
K
K
D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000032:analysis; D000313:Adrenal Medulla / Q000032:analysis*; D000818:Animals; D002417:Cattle; D004174:Diprenorphine / Q000378:metabolism; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D016308:Enkephalin, Leucine-2-Alanine; D019204:GTP-Binding Proteins / Q000032:analysis*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D007981:Levorphanol / Q000494:pharmacology; D037342:Pertussis Toxin; D011957:Receptors, Opioid / Q000032:analysis* / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D011957:Receptors, Opioid; D010566:Virulence Factors, Bordetella; D004174:Diprenorphine; D007981:Levorphanol; D006165:Guanylyl Imidodiphosphate; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases