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Conference Paper: Melatonin and rat epididymal epithelial cell proliferation: possible mechanisms of actions.

TitleMelatonin and rat epididymal epithelial cell proliferation: possible mechanisms of actions.
Authors
Issue Date2000
PublisherS Karger AG. The Journal's web site is located at http://www.karger.com/NSG
Citation
The 1999 International Symposium on Receptor and Non-Receptor Mediated Actions of Melatonin, Hong Kong, China, 6-8 November 1999. In Biological Signals and Receptors, 2000, v. 9 n. 1, p. 60-61 How to Cite?
AbstractPrevious studies by our group have demonstrated the presence of putative high affinity 2-[125I]iodomelatonin binding sites in the rat corpus epididymidis, thus indicating a novel direct action of melatonin on the physiology of the epididymis [1]. To explore the possible actions and attendant mechanisms of melatonin on the rat epididymis, the effect of melatonin on the proliferation of corpus-epididymal epithelial cells was studied. Melatonin was found to stimulate rat corpusepididymal epithelial cell proliferation as determined by tritiated thymidine incorporation and flow cytometric analyses. The stimulatory effect of melatonin was dependent on the concentration and duration of exposure to the hormone. Maximal stimulation of [3H]thymidine incorporation into epididymal epithelial cells by melatonin was observed at 1 nM 5•-dihydrotestosterone, while lower or higher concentrations of androgen attenuated the stimulatory effect of melatonin. Interestingly, a MEL1B (MT2) receptor ligand (4-phenyl-2-propionamidotetraline, 4-PPDOT) and a nuclear melatonin receptor agonist (1-[3-allyl-4-oxothiazolidine-2-ylidene]-4-methyl-thiosemi-carbazone, CGP52608) induced, respectively, similar and opposite effects on epithelial cell proliferation to that produced by melatonin. Moreover, epididymal epithelial cell proliferation was inhibited by 8-bromo-cAMP. Given the expression of Gi-coupled MEL1A (mt1) and MEL1B (MT2) receptors in the principal and basal epithelial cells of the rat corpus epididymidis [2], our data suggest that melatonin may act to stimulate epithelial cell proliferation via inhibition of cAMP signaling pathway through MEL1A (mt1) and MEL1B (MT2) receptors in the rat epididymis. It is possible that in young adult rats, MEL1A (mt1) and MEL1B (MT2) receptor-mediated stimulation of epithelial cell proliferation is important for the maintenance of the architectural organization of the functional epithelium in the corpus epididymidis by replacing effete principal and basal cells. References 1 Shiu SYW, Chow PH, Yu ZH, Tang F, Pang SF: Autoradiographic distribution and physiological regulation of 2-[125I]iodomelatonin binding in rat epididymis. Life Sci 1996;59:1165–1174. 2 Li L, Xu JN, Wong YH, Wong JTY, Pang SF, Shiu SYW: Molecular and cellular analyses of melatonin receptormediated cAMP signaling in rat corpus epididymis. J Pineal Res 1998;25:219–228.
Descriptionpp. 53-75 of this journal issue entitled: Receptor and Non-Receptor Mediated Actions of Melatonin - International Symposium, Hong Kong, China, November 6-8, 1999
Persistent Identifierhttp://hdl.handle.net/10722/104901
ISSN
2003 Impact Factor: 3.5

 

DC FieldValueLanguage
dc.contributor.authorLi, Len_HK
dc.contributor.authorMo, CWen_HK
dc.contributor.authorPang, SFen_HK
dc.contributor.authorShiu, SYWen_HK
dc.date.accessioned2010-09-25T22:12:07Z-
dc.date.available2010-09-25T22:12:07Z-
dc.date.issued2000en_HK
dc.identifier.citationThe 1999 International Symposium on Receptor and Non-Receptor Mediated Actions of Melatonin, Hong Kong, China, 6-8 November 1999. In Biological Signals and Receptors, 2000, v. 9 n. 1, p. 60-61en_HK
dc.identifier.issn1422-4933en_HK
dc.identifier.urihttp://hdl.handle.net/10722/104901-
dc.descriptionpp. 53-75 of this journal issue entitled: Receptor and Non-Receptor Mediated Actions of Melatonin - International Symposium, Hong Kong, China, November 6-8, 1999-
dc.description.abstractPrevious studies by our group have demonstrated the presence of putative high affinity 2-[125I]iodomelatonin binding sites in the rat corpus epididymidis, thus indicating a novel direct action of melatonin on the physiology of the epididymis [1]. To explore the possible actions and attendant mechanisms of melatonin on the rat epididymis, the effect of melatonin on the proliferation of corpus-epididymal epithelial cells was studied. Melatonin was found to stimulate rat corpusepididymal epithelial cell proliferation as determined by tritiated thymidine incorporation and flow cytometric analyses. The stimulatory effect of melatonin was dependent on the concentration and duration of exposure to the hormone. Maximal stimulation of [3H]thymidine incorporation into epididymal epithelial cells by melatonin was observed at 1 nM 5•-dihydrotestosterone, while lower or higher concentrations of androgen attenuated the stimulatory effect of melatonin. Interestingly, a MEL1B (MT2) receptor ligand (4-phenyl-2-propionamidotetraline, 4-PPDOT) and a nuclear melatonin receptor agonist (1-[3-allyl-4-oxothiazolidine-2-ylidene]-4-methyl-thiosemi-carbazone, CGP52608) induced, respectively, similar and opposite effects on epithelial cell proliferation to that produced by melatonin. Moreover, epididymal epithelial cell proliferation was inhibited by 8-bromo-cAMP. Given the expression of Gi-coupled MEL1A (mt1) and MEL1B (MT2) receptors in the principal and basal epithelial cells of the rat corpus epididymidis [2], our data suggest that melatonin may act to stimulate epithelial cell proliferation via inhibition of cAMP signaling pathway through MEL1A (mt1) and MEL1B (MT2) receptors in the rat epididymis. It is possible that in young adult rats, MEL1A (mt1) and MEL1B (MT2) receptor-mediated stimulation of epithelial cell proliferation is important for the maintenance of the architectural organization of the functional epithelium in the corpus epididymidis by replacing effete principal and basal cells. References 1 Shiu SYW, Chow PH, Yu ZH, Tang F, Pang SF: Autoradiographic distribution and physiological regulation of 2-[125I]iodomelatonin binding in rat epididymis. Life Sci 1996;59:1165–1174. 2 Li L, Xu JN, Wong YH, Wong JTY, Pang SF, Shiu SYW: Molecular and cellular analyses of melatonin receptormediated cAMP signaling in rat corpus epididymis. J Pineal Res 1998;25:219–228.-
dc.languageengen_HK
dc.publisherS Karger AG. The Journal's web site is located at http://www.karger.com/NSGen_HK
dc.relation.ispartofBiological Signals and Receptorsen_HK
dc.rightsBiological Signals and Receptors. Copyright © S Karger AG.en_HK
dc.titleMelatonin and rat epididymal epithelial cell proliferation: possible mechanisms of actions.en_HK
dc.typeConference_Paperen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1422-4933&volume=9&spage=60&epage=61&date=2000&atitle=Melatonin+and+rat+epididymal+epithelial+cell+proliferation:+possible+mechanisms+of+actions.en_HK
dc.identifier.emailMo, HCW: hcwmo@HKUCC.hku.hken_HK
dc.identifier.emailPang, SF: hrmypsf@hkucc.hku.hken_HK
dc.identifier.emailShiu, SYW: sywshiu@hkucc.hku.hken_HK
dc.identifier.authorityShiu, SYW=rp00384en_HK
dc.identifier.doi10.1159/000014623-
dc.identifier.hkuros51410en_HK
dc.identifier.volume9en_HK
dc.identifier.issue1-
dc.identifier.spage60en_HK
dc.identifier.epage61en_HK

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