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Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles

BACKGROUND: Sheep are seasonal breeders. The key factor governing seasonal changes in the reproductive activity of the ewe is increased negative feedback of estradiol at the level of the hypothalamus under long-day conditions. It has previously been demonstrated that when gonadotropin secretions are...

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Autores principales: Thiéry, Jean-Claude, Lomet, Didier, Bougoin, Sylvain, Malpaux, Benoit
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2731051/
https://www.ncbi.nlm.nih.gov/pubmed/19653900
http://dx.doi.org/10.1186/1743-8454-6-9
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author Thiéry, Jean-Claude
Lomet, Didier
Bougoin, Sylvain
Malpaux, Benoit
author_facet Thiéry, Jean-Claude
Lomet, Didier
Bougoin, Sylvain
Malpaux, Benoit
author_sort Thiéry, Jean-Claude
collection PubMed
description BACKGROUND: Sheep are seasonal breeders. The key factor governing seasonal changes in the reproductive activity of the ewe is increased negative feedback of estradiol at the level of the hypothalamus under long-day conditions. It has previously been demonstrated that when gonadotropin secretions are inhibited during long days, there is a higher concentration of estradiol in the cerebrospinal fluid (CSF) than during short days. This suggests an involvement of the CSF and choroid plexus in the neuroendocrine regulatory loop, but the mechanisms underlying this phenomenon remain unknown. One possible explanation of this difference in hormonal content is an effect of concentration or dilution caused by variations in CSF secretion rate. The aim of this study was thus to investigate changes in the CSF turnover rate related to light-dark cycles. METHODS: The turnover rate of the CSF was estimated by measuring the time taken for the recovery of intraventricular pressure (IVP) after removal of a moderate volume (0.5 to 2 ml) of CSF (slope in mmHg/min). The turnover rate was estimated three times in the same group of sheep: during a natural period of decreasing day-length corresponding to the initial period when gonadotropin activity is stimulated (SG1), during a long-day inhibitory period (IG), and finally during a short-day stimulatory period (SG2). RESULTS: The time taken and the speed of recovery of initial IVP differed between groups: 8 min 30 sec, 0.63 ± 0.07 mmHg/min(SG1), 11 min 1 sec, 0.38 ± 0.06 mmHg/min (IG) and 9 min 0 sec, 0.72 ± 0.15 mmHg/min (SG2). Time changes of IVP differed between groups (ANOVA, p < 0.005, SG1 different from IG, p < 0.05). The turnover rate in SG2: 183.16 ± 23.82 μl/min was not significantly different from SG1: 169. 23 ± 51.58 μl/min (Mann-Whitney test, p = 0.41), but was significantly different from IG: 71.33 ± 16.59 μl/min (p = 0.016). CONCLUSION: This study shows that the turnover rate of CSF in ewes changes according to the light-dark cycle; it is increased during short day periods and reduced in long day periods. This phenomenon could account for differences in hormonal concentrations in the CSF in this seasonal species.
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spelling pubmed-27310512009-08-24 Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles Thiéry, Jean-Claude Lomet, Didier Bougoin, Sylvain Malpaux, Benoit Cerebrospinal Fluid Res Research BACKGROUND: Sheep are seasonal breeders. The key factor governing seasonal changes in the reproductive activity of the ewe is increased negative feedback of estradiol at the level of the hypothalamus under long-day conditions. It has previously been demonstrated that when gonadotropin secretions are inhibited during long days, there is a higher concentration of estradiol in the cerebrospinal fluid (CSF) than during short days. This suggests an involvement of the CSF and choroid plexus in the neuroendocrine regulatory loop, but the mechanisms underlying this phenomenon remain unknown. One possible explanation of this difference in hormonal content is an effect of concentration or dilution caused by variations in CSF secretion rate. The aim of this study was thus to investigate changes in the CSF turnover rate related to light-dark cycles. METHODS: The turnover rate of the CSF was estimated by measuring the time taken for the recovery of intraventricular pressure (IVP) after removal of a moderate volume (0.5 to 2 ml) of CSF (slope in mmHg/min). The turnover rate was estimated three times in the same group of sheep: during a natural period of decreasing day-length corresponding to the initial period when gonadotropin activity is stimulated (SG1), during a long-day inhibitory period (IG), and finally during a short-day stimulatory period (SG2). RESULTS: The time taken and the speed of recovery of initial IVP differed between groups: 8 min 30 sec, 0.63 ± 0.07 mmHg/min(SG1), 11 min 1 sec, 0.38 ± 0.06 mmHg/min (IG) and 9 min 0 sec, 0.72 ± 0.15 mmHg/min (SG2). Time changes of IVP differed between groups (ANOVA, p < 0.005, SG1 different from IG, p < 0.05). The turnover rate in SG2: 183.16 ± 23.82 μl/min was not significantly different from SG1: 169. 23 ± 51.58 μl/min (Mann-Whitney test, p = 0.41), but was significantly different from IG: 71.33 ± 16.59 μl/min (p = 0.016). CONCLUSION: This study shows that the turnover rate of CSF in ewes changes according to the light-dark cycle; it is increased during short day periods and reduced in long day periods. This phenomenon could account for differences in hormonal concentrations in the CSF in this seasonal species. BioMed Central 2009-08-04 /pmc/articles/PMC2731051/ /pubmed/19653900 http://dx.doi.org/10.1186/1743-8454-6-9 Text en Copyright © 2009 Thiéry et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Thiéry, Jean-Claude
Lomet, Didier
Bougoin, Sylvain
Malpaux, Benoit
Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title_full Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title_fullStr Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title_full_unstemmed Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title_short Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
title_sort turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2731051/
https://www.ncbi.nlm.nih.gov/pubmed/19653900
http://dx.doi.org/10.1186/1743-8454-6-9
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