Binding of Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) and related peptides to mu 1 and mu 2 opiate receptors.
Neurosci Lett
; 215(1): 65-9, 1996 Aug 30.
Article
em En
| MEDLINE
| ID: mdl-8880755
ABSTRACT
Two endogenous brain peptides (Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) and Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2)), a cyclized analog and two fragments of Tyr-W-MIF-1, and hemorphin (Tyr-Pro-Trp-Thr) were tested for binding to mu 1 and mu 2 opiate receptor. All these peptides bound to both mu 1 and mu 2 sites in assays optimized to discriminate these subtypes of the mu opiate receptor in membranes from bovine thalamus. The cyclized analog of Tyr-W-MIF-1, previously shown to have potency near that of Tyr-D-Ala-Gly-N-MePhe-Gly-ol (DAMGO) and morphine in producing analgesia after intracerebroventricular (i.c.v.) injection, bound to mu 1 and mu 2 sites with affinities similar to those of DAMGO. Tyr-W-MIF-1, previously shown to induce analgesia after i.c.v. injection but with much higher potency after intrathecal (i.t.) injection, also bound to both mu 1 and mu 2 sites with an affinity between that of morphiceptin and hemorphin. Although the highest ratios of Ki's for mu 2/mu 1 were shown by hemorphin, Tyr-W-MIF-1, and Tyr-W-MIF-1, none of the compounds were significantly different in selectivity. The results indicate that the relatively lower potency of Tyr-W-MIF-1 after i.c.v., compared with i.t. injection, is not due to a lack of binding to mu 1 sites. They suggest that it has relatively high efficacy at mu 2, but low efficacy at mu 1 sites, a possibility that might explain some of the novel properties of these peptides.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Tálamo
/
Ligação Competitiva
/
Hormônio Inibidor da Liberação de MSH
/
Receptores Opioides mu
/
Antagonistas de Entorpecentes
Limite:
Animals
Idioma:
En
Revista:
Neurosci Lett
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos