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Article: Receptor binding of gonadotropin-releasing hormone antagonists that inhibit release of gonadotropin-II and growth hormone in goldfish, Carassius auratus

TitleReceptor binding of gonadotropin-releasing hormone antagonists that inhibit release of gonadotropin-II and growth hormone in goldfish, Carassius auratus
Authors
Issue Date1994
PublisherSociety for the Study of Reproduction. The Journal's web site is located at http://www.biolreprod.org/
Citation
Biology Of Reproduction, 1994, v. 51 n. 3, p. 349-357 How to Cite?
AbstractIn goldfish, GnRH stimulates gonadotropin-II (GTH-II) and growth hormone (GH) release. The two native forms of GnRH, salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II), bind to two classes of GnRH binding sites: high- affinity/low-capacity sites and low-affinity/high-capacity sites. Our previous in vitro perifusion studies of goldfish pituitary fragments showed that [Ac-Δ3-Pro1, 4FD-Phe2, D-Trp3,6]-mGnRH (analog E), [Ac-Δ3- Pro1, 4FD-Phe2, D-Trp3,6]-sGnRH (analog C), and [Ac-D(2)Nal1, 4Cl-D- Phe2, D-(3)Pal3,6]-cGnRH-II (analog N) inhibited both sGnRH- and cGnRH- II-stimulated GTH-II and GH release. Interestingly, analog C stimulated GH release but not GTH-II release. The objectives of the present study were 1) to test the site of action of GnRH antagonists in goldfish, 2) to test the relationship between receptor binding affinity of antagonists and their in vitro inhibitory potencies and apparent duration of action, and 3) to compare the binding characteristics of analog C with its differential action on GTH- II and GH release. As in previous studies, analog E suppressed sGnRH- stimulated GTH-II and GH release from perifused pituitary fragments. Similarly, analog E suppressed both sGnRH- and cGnRH-II-stimulated GTH-II and GH release from perifused dispersed goldfish pituitary cells, indicating the direct action of GnRH antagonists at the pituitary cell level. In the receptor binding studies, analog E displaced 125I-[D-Arg6, Pro9NHEt]- sGnRH (sGnRH-A) from crude goldfish pituitary membrane preparations in a dose-dependent manner. The binding affinities to high-affinity GnRH binding sites of analog E, analog C, and analog N were significantly higher than those of native sGnRH and sGnRH-A. The rank order of high affinity was analog N ≥ C > E, and binding affinity had no positive relation with the inhibitory effects of these analogs on GTH-II or GH release in vitro. In conclusion, GnRH antagonists inhibit native GnRH-stimulated GTH-II and GH release by competitively binding to binding sites at the pituitary cells, although there was no positive relation between receptor binding affinity and in vitro GTH- II or GH release-inhibiting potency of the analogs tested.
Persistent Identifierhttp://hdl.handle.net/10722/49434
ISSN
2015 Impact Factor: 3.471
2015 SCImago Journal Rankings: 1.646
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorMurthy, CKen_HK
dc.contributor.authorWong, AOLen_HK
dc.contributor.authorHabibi, HRen_HK
dc.contributor.authorRivier, JEen_HK
dc.contributor.authorPeter, REen_HK
dc.date.accessioned2008-06-12T06:42:33Z-
dc.date.available2008-06-12T06:42:33Z-
dc.date.issued1994en_HK
dc.identifier.citationBiology Of Reproduction, 1994, v. 51 n. 3, p. 349-357en_HK
dc.identifier.issn0006-3363en_HK
dc.identifier.urihttp://hdl.handle.net/10722/49434-
dc.description.abstractIn goldfish, GnRH stimulates gonadotropin-II (GTH-II) and growth hormone (GH) release. The two native forms of GnRH, salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II), bind to two classes of GnRH binding sites: high- affinity/low-capacity sites and low-affinity/high-capacity sites. Our previous in vitro perifusion studies of goldfish pituitary fragments showed that [Ac-Δ3-Pro1, 4FD-Phe2, D-Trp3,6]-mGnRH (analog E), [Ac-Δ3- Pro1, 4FD-Phe2, D-Trp3,6]-sGnRH (analog C), and [Ac-D(2)Nal1, 4Cl-D- Phe2, D-(3)Pal3,6]-cGnRH-II (analog N) inhibited both sGnRH- and cGnRH- II-stimulated GTH-II and GH release. Interestingly, analog C stimulated GH release but not GTH-II release. The objectives of the present study were 1) to test the site of action of GnRH antagonists in goldfish, 2) to test the relationship between receptor binding affinity of antagonists and their in vitro inhibitory potencies and apparent duration of action, and 3) to compare the binding characteristics of analog C with its differential action on GTH- II and GH release. As in previous studies, analog E suppressed sGnRH- stimulated GTH-II and GH release from perifused pituitary fragments. Similarly, analog E suppressed both sGnRH- and cGnRH-II-stimulated GTH-II and GH release from perifused dispersed goldfish pituitary cells, indicating the direct action of GnRH antagonists at the pituitary cell level. In the receptor binding studies, analog E displaced 125I-[D-Arg6, Pro9NHEt]- sGnRH (sGnRH-A) from crude goldfish pituitary membrane preparations in a dose-dependent manner. The binding affinities to high-affinity GnRH binding sites of analog E, analog C, and analog N were significantly higher than those of native sGnRH and sGnRH-A. The rank order of high affinity was analog N ≥ C > E, and binding affinity had no positive relation with the inhibitory effects of these analogs on GTH-II or GH release in vitro. In conclusion, GnRH antagonists inhibit native GnRH-stimulated GTH-II and GH release by competitively binding to binding sites at the pituitary cells, although there was no positive relation between receptor binding affinity and in vitro GTH- II or GH release-inhibiting potency of the analogs tested.en_HK
dc.format.extent418 bytes-
dc.format.mimetypetext/html-
dc.languageengen_HK
dc.publisherSociety for the Study of Reproduction. The Journal's web site is located at http://www.biolreprod.org/en_HK
dc.relation.ispartofBiology of Reproductionen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.meshGoldfish - physiologyen_HK
dc.subject.meshGonadotropin-releasing hormone - analogs & derivatives - antagonists & inhibitors - metabolism - pharmacologyen_HK
dc.subject.meshGonadotropins, pituitary - secretionen_HK
dc.subject.meshGrowth hormone - secretionen_HK
dc.subject.meshPituitary gland - drug effects - secretionen_HK
dc.titleReceptor binding of gonadotropin-releasing hormone antagonists that inhibit release of gonadotropin-II and growth hormone in goldfish, Carassius auratusen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0006-3363&volume=51&issue=3&spage=349&epage=357&date=1994&atitle=Receptor+binding+of+gonadotropin-releasing+hormone+antagonists+that+inhibit+release+of+gonadotropin-II+and+growth+hormone+in+goldfish,+Carassius+auratusen_HK
dc.identifier.emailWong, AOL: olwong@hkucc.hku.hken_HK
dc.identifier.authorityWong, AOL=rp00806en_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.pmid7803606-
dc.identifier.scopuseid_2-s2.0-0028060066en_HK
dc.identifier.hkuros5753-
dc.identifier.volume51en_HK
dc.identifier.issue3en_HK
dc.identifier.spage349en_HK
dc.identifier.epage357en_HK
dc.identifier.isiWOS:A1994PC92000001-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridMurthy, CK=13309818400en_HK
dc.identifier.scopusauthoridWong, AOL=7403147570en_HK
dc.identifier.scopusauthoridHabibi, HR=7004599227en_HK
dc.identifier.scopusauthoridRivier, JE=35411857000en_HK
dc.identifier.scopusauthoridPeter, RE=7202909690en_HK

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