LACK OF MIXED AGONIST-ANTAGONIST PROPERTIES OF [GLN8-GLY31]-BETA-H-EP-GLY-GLY-NH2 AND [ARG9,19,24,28,29]-BETA-H-EP IN THE RAT VAS-DEFERENS NEUROEFFECTOR JUNCTION - STUDIES WITH NALOXONE, BETA-FUNALTREXAMINE AND ICI-174,864

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dc.contributor.authorVALENZUELA, R
dc.contributor.authorCHOH, HL
dc.contributor.authorHUIDOBROTORO, JP
dc.date.accessioned2025-01-23T19:24:12Z
dc.date.available2025-01-23T19:24:12Z
dc.date.issued1989
dc.description.abstractThe 1-27 truncated fragment of .beta.h-endorphin (.beta.h-EP) as well as [Gln8,Gly31]-.beta.h-EP-Gly-Gly-NH2 or [Arg9,19,24,28,29]-.beta.h-EP exhibited opiate agonist activity in the rat vas deferens bioassay; the potency of these peptides was 3 to 6 times less than that of .beta.h-EP. None of these compounds exhibited any degree of antagonism towards the inhibitory action of .beta.h-EP. Naloxone antagonized and reversed the inhibitory action of .beta.h-EP and its analogues though with varying potencies. The apparent naloxone-pA2 value for .beta.h-EP was 8.94; that for [Gln8-Gly31]-.beta.h-EP-Gly-Gly-NH2 was 8.08 and that for [Arg9,19,24,28,29]-.beta.h-EP was 8.38. .beta.-Funaltrexamine (.beta.-FNA) potently antagonized the inhibitory action of .beta.h-EP following non-equilibrium kinetics. Tissue preincubation with 10 nM .beta.-FNA for 60 min followed by extensive washing caused a 10-fold increase in the .beta.h-EP IC50. However, 10 nM .beta.-FNA caused only a 1.2 increase in the IC50 of [Gln8 Gly31]-.beta.h-EP-Gly-Gly-NH2 and a 4.1-fold increase in the IC50 of [Arg9,19,24,28,29]-.beta.h-EP. In contrast, preincubation of the tissue with 3 .mu.M ICI 174,864 did not modify the potency of .beta.h-EP or its structural analogues. However, a 60 min pretreatment with 10 .mu.M .beta.-FNA followed by the addition of 3 .mu.M ICI 174,864 revealed a further decrease in the potency of the opiopeptins compared with tissues exposed to .beta.-FNA alone or ICI 174,864 alone. In conclusion, the inhibitory action of these peptides is remarkably sensitive to .beta.-FNA antagonism; in addition the peptides act as pure opiate agonists in marked contrast with the agonist-antagonist properties described in the CNS.
dc.fuente.origenWOS
dc.identifier.eissn2042-7158
dc.identifier.issn0022-3573
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/99323
dc.identifier.wosidWOS:A1989U062900009
dc.issue.numero2
dc.language.isoen
dc.pagina.final96
dc.pagina.inicio92
dc.revistaJournal of pharmacy and pharmacology
dc.rightsacceso restringido
dc.subject.ods03 Good Health and Well-being
dc.subject.odspa03 Salud y bienestar
dc.titleLACK OF MIXED AGONIST-ANTAGONIST PROPERTIES OF [GLN8-GLY31]-BETA-H-EP-GLY-GLY-NH2 AND [ARG9,19,24,28,29]-BETA-H-EP IN THE RAT VAS-DEFERENS NEUROEFFECTOR JUNCTION - STUDIES WITH NALOXONE, BETA-FUNALTREXAMINE AND ICI-174,864
dc.typeartículo
dc.volumen41
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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