| The type 2 corticotrophin-releasing hormone receptor mediates orexin A-induced luteinising hormone suppression in ovariectomised rats. | |
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MedLine Citation:
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PMID: 17680889 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Orexins are thought to be regulatory factors of the arousal and sleep patterns. They also affect immune, feeding, autonomic and neuroendocrine systems. We have previously shown that intracerebroventricular (i.c.v.) injection of orexin decreases pulsatile luteinising hormone (LH) secretion in ovariectomised (OVX) rats. However, the details of this mechanism have not been fully examined. Intracerebroventricular injection of orexin A also stimulates corticotrophin-releasing hormone (CRH) systems, which have been implicated in the stress-induced suppression of reproductive function. In the present study, we investigated the role of CRH systems in orexin-induced LH suppression. OVX rats were implanted with i.c.v. and intravenous (i.v.) cannulae. After i.c.v. injection of orexin and/or CRH receptor antagonists, blood samples were collected through the i.v. cannula at 6-min intervals for 120 min for LH measurement. Intracerebroventricular injection of orexin A or B (3 nmol/2.5 microl) suppressed pulsatile LH secretion. Coadministration of orexin A and alpha-helical corticotrophic-releasing factor (CRF), a nonselective CRH receptor antagonist (13 nmol/2.5 microl), or astressin(2)B, a selective type2 (CRH-R2) CRH receptor antagonist (28 nmol/2.5 microl), partly restored pulsatile LH secretion. Orexin B-induced LH suppression was not restored by alpha-helical CRF. In addition, i.c.v. injection of orexin A increased CRH and urocortin II (UcnII), but not Ucn mRNA levels, in the hypothalamus. These findings suggest that CRH-R2 mediates orexin A-induced LH suppression and it is possible that CRH and UcnII in the hypothalamus are involved in this pathway. |
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Authors:
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T Iwasa; T Matsuzaki; M Kiyokawa; F Shimizu; M Minakuchi; A Kuwahara; M Maegawa; T Yasui; M Irahara |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of neuroendocrinology Volume: 19 ISSN: 0953-8194 ISO Abbreviation: J. Neuroendocrinol. Publication Date: 2007 Sep |
Date Detail:
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Created Date: 2007-08-07 Completed Date: 2007-10-23 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8913461 Medline TA: J Neuroendocrinol Country: England |
Other Details:
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Languages: eng Pagination: 732-8 Citation Subset: IM |
Affiliation:
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Department of Obstetrics and Gynecology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan. takeshi1@clin.med.tokushima-u.ac.jp |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Corticotropin-Releasing Hormone / genetics, metabolism Female Hypothalamus / metabolism Intracellular Signaling Peptides and Proteins / metabolism* Luteinizing Hormone / blood* Neuropeptides / metabolism* Ovariectomy* Rats Rats, Wistar Receptors, Corticotropin-Releasing Hormone / genetics, metabolism* Urocortins |
| Chemical | |
Reg. No./Substance:
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0/CRF receptor type 2; 0/Intracellular Signaling Peptides and Proteins; 0/Neuropeptides; 0/Receptors, Corticotropin-Releasing Hormone; 0/Urocortins; 0/orexins; 9002-67-9/Luteinizing Hormone; 9015-71-8/Corticotropin-Releasing Hormone |
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