| Energy balance and ovulation: small cages versus natural habitats. | |
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MedLine Citation:
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PMID: 9801265 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In the laboratory, ovulation is suppressed when a mammal is in negative energy balance whether that state is caused by inadequate food intake, excessive locomotor activity or heavy thermoregulatory costs. In this paper, knowledge generated in the laboratory about the link between ovulation and energy balance is examined in relation to the kinds of energetic challenges mammals actually face in natural habitats. When viewed in that context, several conclusions can be drawn. First, females ovulate whenever extant energetic conditions permit unless the process is blocked by non-metabolic stress, social cues or a predictive seasonal cue such as photoperiod. In the latter case, most mammals show at least a seasonal tendency in their reproduction and the majority do not use a predictive cue; they reproduce opportunistically in relation to seasonal variation in the energetic characteristics of their environment. Second, the widely held assumption that a female's fat reserves must exceed a critical level in order that she may ovulate finds no support in the literature dealing with natural populations. Third, the surprisingly rapid responsiveness of the gonadotrophin releasing hormone (GnRH) pulse generator to energetic manipulation probably reflects the study of animals that are in a pure survival mode. Fourth, the complexity of the energetic challenges mammals face in the wild suggests that there are probably multiple metabolic and neural pathways coupling ovulation to energy balance and that these pathways are probably characterized by considerable overlap and redundancy. Thus, fifth, to develop a more realistic overview of these pathways there is a need for experimental designs that present mammals with the kinds of complex challenges they actually face in the wild habitats in which they evolved. |
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Authors:
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F H Bronson |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S.; Review |
Journal Detail:
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Title: Reproduction, fertility, and development Volume: 10 ISSN: 1031-3613 ISO Abbreviation: Reprod. Fertil. Dev. Publication Date: 1998 |
Date Detail:
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Created Date: 1999-01-05 Completed Date: 1999-01-05 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8907465 Medline TA: Reprod Fertil Dev Country: AUSTRALIA |
Other Details:
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Languages: eng Pagination: 127-37 Citation Subset: IM |
Affiliation:
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Institute of Reproductive Biology, Department of Zoology, University of Texas at Austin, USA. bronson@mail.utexas.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adipose Tissue
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physiology Animals Energy Metabolism / physiology* Female Gonadotropin-Releasing Hormone / physiology Housing, Animal* Mammals / physiology Ovulation / physiology* Seasons |
| Grant Support | |
ID/Acronym/Agency:
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HD-26823/HD/NICHD NIH HHS |
| Chemical | |
Reg. No./Substance:
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33515-09-2/Gonadotropin-Releasing Hormone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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