Evidence for interaction between central beta-2 adrenoceptors and epinephrine pathways in the opioid-induced prolactin rise in the rat.
1. The possible role of central beta-2 adrenoceptors and epinephrine pathways in opioid-induced prolactin (PRL) rise was investigated. 2. FK 33824, a synthetic opioid peptide injected into the third ventricle of Wistar male rats, generated a PRL rise that was significantly reduced by pretreatment with IPS 339, a potent and selective beta-2 antagonist. 3. Inhibition of central epinephrine synthesis with SKF 64 139, which selectively blocks phenylethanolamine-N-methyltransferase, partially decreased the PRL release induced by FK 33824. 4. Practolol, a selective beta-1 adrenoceptor blocker, did not modify the PRL secretion induced by FK 33824. 5. The results indicate that this FK 33824-induced PRL rise depends in part on the functional integrity of central beta-2 adrenoceptors and that epinephrine pathways in the brain may play an important role in the mechanisms by which opioid peptides increase PRL secretion.
De Castro-e-Silva
E
E
Departamento de Fisiologia, Universidade Federal da Bahia, Salvador, Brasil.
Antunes-Rodrigues
J
J
D000818:Animals; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000494:pharmacology*; D004837:Epinephrine / Q000096:biosynthesis*; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D010625:Phenylethanolamine N-Methyltransferase / Q000037:antagonists & inhibitors; D011388:Prolactin / Q000097:blood*; D011412:Propanolamines / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D044005:Tetrahydroisoquinolines
D007546:Isoquinolines; D011412:Propanolamines; D044005:Tetrahydroisoquinolines; C014898:IPS 339; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D011388:Prolactin; C012153:7,8-dichloro-1,2,3,4-tetrahydroisoquinoline; D010625:Phenylethanolamine N-Methyltransferase; D004837:Epinephrine