Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons

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dc.contributor.advisorMillar, Robert Pen_ZA
dc.contributor.advisorDutlow, Cliveen_ZA
dc.contributor.authorPithey, Anne Louiseen_ZA
dc.date.accessioned2018-01-29T06:45:49Z
dc.date.available2018-01-29T06:45:49Z
dc.date.issued1994en_ZA
dc.description.abstractThe existence of an ultrashort feedback mechanism regulating GnRH secretion has been supported from in vivo and in vitro studies. However, the complex synaptic connections of GnRH neurons with other neural elements made it difficult to determine whether the regulation was mediated by direct actions on the GnRH neurons or through actions on other interneurons. The recent development of the GnRH-secreting neuronal cell line, GT1, provided a model system for the study of neural regulation of a pure population of GnRH neurons. The present studies utilized GT1 -7 cells to investigate whether GnRH (at the level of the nerve terminal) influences the control of its own release. Preliminary studies determined the presence of GnRH mRNA in GT1-7 cells and established a cell culture system for the analysis of secretagogue-induced GnRH release. In this system GnRH release was shown to be spontaneous and was enhanced by the addition of K⁺, L-GLU, forskolin and PMA. Furthermore, K⁺- and forskolin-induced GnRH release was dependent on extracellular Ca²⁺. For the analysis of an ultrashort feedback mechanism, GT1-7 cells were cultured in 6-well plates to near confluence and then incubated in serum-free medium in the presence (1 nM- 1 μM) or absence of GnRH antagonist, Ant 27. Basal, K⁺-and forskolin-induced secretion of GnRH was monitored with antiserum 1076 which does not cross-react with Ant 27 at> 1 μM. Ant 27 treatment increased basal, K⁺- and forskolin-stimulated GnRH release in a dose-dependent manner. Total content was unaffected by 18 h treatment of GT1-7 cells with Ant 27. This suggests that the effects of Ant 27 are at the level of release and not biosynthesis. The presence of GnRH binding sites in the cells was demonstrated with ¹²⁵I-GnRH analog. These findings support the concept that GnRH, acting via autoreceptors, negatively controls its own release.en_ZA
dc.identifier.apacitationPithey, A. L. (1994). <i>Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Division of Chemical Pathology. Retrieved from http://hdl.handle.net/11427/27030en_ZA
dc.identifier.chicagocitationPithey, Anne Louise. <i>"Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Division of Chemical Pathology, 1994. http://hdl.handle.net/11427/27030en_ZA
dc.identifier.citationPithey, A. 1994. Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Pithey, Anne Louise AB - The existence of an ultrashort feedback mechanism regulating GnRH secretion has been supported from in vivo and in vitro studies. However, the complex synaptic connections of GnRH neurons with other neural elements made it difficult to determine whether the regulation was mediated by direct actions on the GnRH neurons or through actions on other interneurons. The recent development of the GnRH-secreting neuronal cell line, GT1, provided a model system for the study of neural regulation of a pure population of GnRH neurons. The present studies utilized GT1 -7 cells to investigate whether GnRH (at the level of the nerve terminal) influences the control of its own release. Preliminary studies determined the presence of GnRH mRNA in GT1-7 cells and established a cell culture system for the analysis of secretagogue-induced GnRH release. In this system GnRH release was shown to be spontaneous and was enhanced by the addition of K⁺, L-GLU, forskolin and PMA. Furthermore, K⁺- and forskolin-induced GnRH release was dependent on extracellular Ca²⁺. For the analysis of an ultrashort feedback mechanism, GT1-7 cells were cultured in 6-well plates to near confluence and then incubated in serum-free medium in the presence (1 nM- 1 μM) or absence of GnRH antagonist, Ant 27. Basal, K⁺-and forskolin-induced secretion of GnRH was monitored with antiserum 1076 which does not cross-react with Ant 27 at> 1 μM. Ant 27 treatment increased basal, K⁺- and forskolin-stimulated GnRH release in a dose-dependent manner. Total content was unaffected by 18 h treatment of GT1-7 cells with Ant 27. This suggests that the effects of Ant 27 are at the level of release and not biosynthesis. The presence of GnRH binding sites in the cells was demonstrated with ¹²⁵I-GnRH analog. These findings support the concept that GnRH, acting via autoreceptors, negatively controls its own release. DA - 1994 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1994 T1 - Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons TI - Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons UR - http://hdl.handle.net/11427/27030 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/27030
dc.identifier.vancouvercitationPithey AL. Autocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neurons. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Division of Chemical Pathology, 1994 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/27030en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDivision of Chemical Pathologyen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemical Pathologyen_ZA
dc.subject.otherAutocrine Motility Factoren_ZA
dc.subject.otherGonadorelinen_ZA
dc.subject.otherReceptors, LHRHen_ZA
dc.titleAutocrine regulation of gonadotropin-releasing hormone in immortalized hypothalamic GT1-7 neuronsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Med)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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