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Article: Serotonin interferes Ca2+ and PKC signaling to reduce gonadotropin-releasing hormone-stimulated growth hormone secretion in goldfish pituitary cells.

TitleSerotonin interferes Ca2+ and PKC signaling to reduce gonadotropin-releasing hormone-stimulated growth hormone secretion in goldfish pituitary cells.
Authors
Issue Date2008
PublisherAcademic Press. The Journal's web site is located at http://www.elsevier.com/locate/ygcen
Citation
General and Comparative Endocrinology, 2008, v. 159 n. 1, p. 58-66 How to Cite?
AbstractIn goldfish, two endogenous gonadotropin-releasing hormones (GnRH), salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II), are thought to stimulate growth hormone (GH) release via protein kinase C (PKC) and subsequent increases in intracellular Ca(2+) levels ([Ca(2+)](i)). In contrast, the signaling mechanism for serotonin (5-HT) inhibition of GH secretion is still unknown. In this study, whether 5-HT inhibits GH release by actions at sites along the PKC and Ca(2+) signal transduction pathways leading to hormone release were examined in primary cultures of goldfish pituitary cells. Under static incubation and column perifusion conditions, 5-HT reduced basal, as well as sGnRH- and cGnRH-II-stimulated, GH secretion. 5-HT also suppressed GH responses to two PKC activators but had no effect on the GH-releasing action of the Ca(2+) ionophore ionomycin. Ca(2+)-imaging studies with identified somatotropes revealed that 5-HT did not alter basal [Ca(2+)](i) but attenuated the magnitude of the [Ca(2+)](i) responses to the two GnRHs. Prior treatment with 5-HT and cGnRH-II reduced the magnitude of the [Ca(2+)](i) responses induced by depolarizing levels of K(+). Similar inhibition, however, was not observed with prior treatment of 5-HT and sGnRH. These results suggest that 5-HT, by direct actions at the somatotrope level, interferes with PKC and Ca(2+) signaling pathways to reduce the GH-releasing effect of GnRH. 5-HT action may occur at the level of PKC activation or its downstream signaling events prior to the subsequent rise in [Ca(2+)](i.). The differential Ca(2+) responses by depolarizing doses of K(+) is consistent with our previous findings that sGnRH and cGnRH-II are coupled to overlapping and yet distinct Ca(2+)-dependent mechanisms.
Persistent Identifierhttp://hdl.handle.net/10722/60680
ISSN
2015 Impact Factor: 2.667
2015 SCImago Journal Rankings: 1.245
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorYu, Yen_HK
dc.contributor.authorWong, AOLen_HK
dc.contributor.authorChang, JPen_HK
dc.date.accessioned2010-05-31T04:16:24Z-
dc.date.available2010-05-31T04:16:24Z-
dc.date.issued2008en_HK
dc.identifier.citationGeneral and Comparative Endocrinology, 2008, v. 159 n. 1, p. 58-66en_HK
dc.identifier.issn0016-6480en_HK
dc.identifier.urihttp://hdl.handle.net/10722/60680-
dc.description.abstractIn goldfish, two endogenous gonadotropin-releasing hormones (GnRH), salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II), are thought to stimulate growth hormone (GH) release via protein kinase C (PKC) and subsequent increases in intracellular Ca(2+) levels ([Ca(2+)](i)). In contrast, the signaling mechanism for serotonin (5-HT) inhibition of GH secretion is still unknown. In this study, whether 5-HT inhibits GH release by actions at sites along the PKC and Ca(2+) signal transduction pathways leading to hormone release were examined in primary cultures of goldfish pituitary cells. Under static incubation and column perifusion conditions, 5-HT reduced basal, as well as sGnRH- and cGnRH-II-stimulated, GH secretion. 5-HT also suppressed GH responses to two PKC activators but had no effect on the GH-releasing action of the Ca(2+) ionophore ionomycin. Ca(2+)-imaging studies with identified somatotropes revealed that 5-HT did not alter basal [Ca(2+)](i) but attenuated the magnitude of the [Ca(2+)](i) responses to the two GnRHs. Prior treatment with 5-HT and cGnRH-II reduced the magnitude of the [Ca(2+)](i) responses induced by depolarizing levels of K(+). Similar inhibition, however, was not observed with prior treatment of 5-HT and sGnRH. These results suggest that 5-HT, by direct actions at the somatotrope level, interferes with PKC and Ca(2+) signaling pathways to reduce the GH-releasing effect of GnRH. 5-HT action may occur at the level of PKC activation or its downstream signaling events prior to the subsequent rise in [Ca(2+)](i.). The differential Ca(2+) responses by depolarizing doses of K(+) is consistent with our previous findings that sGnRH and cGnRH-II are coupled to overlapping and yet distinct Ca(2+)-dependent mechanisms.-
dc.languageengen_HK
dc.publisherAcademic Press. The Journal's web site is located at http://www.elsevier.com/locate/ygcenen_HK
dc.relation.ispartofGeneral and Comparative Endocrinologyen_HK
dc.subject.meshCalcium - metabolism-
dc.subject.meshGonadotropin-Releasing Hormone - pharmacology-
dc.subject.meshGrowth Hormone - metabolism-
dc.subject.meshPituitary Gland - cytology - drug effects - metabolism-
dc.subject.meshSerotonin - pharmacology-
dc.titleSerotonin interferes Ca2+ and PKC signaling to reduce gonadotropin-releasing hormone-stimulated growth hormone secretion in goldfish pituitary cells.en_HK
dc.typeArticleen_HK
dc.identifier.emailWong, AOL: olwong@HKUCC.hku.hken_HK
dc.identifier.authorityWong, AOL=rp00806en_HK
dc.identifier.doi10.1016/j.ygcen.2008.07.021-
dc.identifier.pmid18723020-
dc.identifier.hkuros164842en_HK
dc.identifier.volume159-
dc.identifier.issue1-
dc.identifier.spage58-
dc.identifier.epage66-
dc.identifier.isiWOS:000260596300007-
dc.publisher.placeUnited States-

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