RESUMO
Nociceptin/orphanin FQ (N/OFQ) is an endogenous neuropeptide, which is widely distributed in central and peripheral nervous system. Some N/OFQ sequence unrelated hexapeptides can effectively bind to the N/OFQ peptide (NOP) receptor and they were used as template for structure-activity studies that lead to discovery of the new NOP selective ligands. In the present study, the pharmacological profile of the novel hexapeptide Ac-RYYRIR-ol was investigated using various in vitro assays including receptor binding and G-protein activation in rat brain membranes, mouse and rat vas deferens, guinea pig ileum, mouse colon and Ca(2+) mobilization assay in chinese hamster ovary (CHO) cells co-expressing the human recombinant NOP receptor and the C-terminally modified Galpha(qi5) protein. In rat brain membranes Ac-RYYRIR-ol displaced both [(3)H]nociceptin/OFQ and [(3)H]Ac-RYYRIK-ol with high affinity (pK(i) 9.35 and 8.81, respectively) and stimulated [(35)S]GTPgammaS binding showing however lower maximal effects than N/OFQ (alpha=0.28). The stimulatory effect of Ac-RYYRIR-ol was antagonized by the selective NOP receptor antagonist UFP-101. In the electrically stimulated mouse vas deferens Ac-RYYRIR-ol displayed negligible agonist activity while antagonizing in a competitive manner (pA(2) 7.99) the inhibitory effects of N/OFQ. Similar results were obtained in the rat vas deferens. In the mouse colon Ac-RYYRIR-ol produced concentration dependent contractile effects with similar potency and maximal effects as N/OFQ. Finally, in the Ca(2+) mobilization assay performed with CHO-hNOP-Galpha(qi5) cells Ac-RYYRIR-ol displayed lower potency and maximal effects (alpha=0.87) compared with N/OFQ. In conclusion, the novel NOP receptor selective hexapeptide Ac-RYYRIR-ol has been shown to have fine selectivity, high potency, furthermore agonist and antagonist effects toward the NOP receptors were measured in various assays; this is likely due to its partial agonist pharmacological activity.
Assuntos
Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Receptores Opioides/metabolismo , Animais , Células CHO , Cálcio/metabolismo , Colo/efeitos dos fármacos , Colo/fisiologia , Cricetinae , Cricetulus , Estimulação Elétrica , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Guanosina 5'-O-(3-Tiotrifosfato)/química , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Cobaias , Humanos , Masculino , Camundongos , Contração Muscular/efeitos dos fármacos , Peptídeos Opioides/metabolismo , Peptídeos Opioides/farmacologia , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Receptores Opioides/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Receptor de Nociceptina , NociceptinaRESUMO
Drug discovery directed peptide research has been pursued at the IVAX Drug Research Institute (formerly Institute for Drug Research) (IDR) since the mid 1950s. Outlined are the main projects and the most significant results, which include the first synthesis of human ACTH, the discovery of GYKI-14 166, the prototype of peptide inhibitors of thrombin, a stable anticoagulant, efegatran GYKI-14 766, and their dual acting analogues. The identification of an agonist analogue of LHRH leading to Cetrorelix, an LHRH antagonist now in clinical use, is also presented.