Increases in norepinephrine release and ovarian cyst formation during ageing in the rat
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Increases in norepinephrine release and ovarian cyst formation during ageing in the rat Eric Acuña, Romina Fornes, Daniela Fernandois, Maritza P Garrido, Monika Greiner, Hernan E Lara and Alfonso H Paredes* Address: Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Chile Email: Eric Acuña - [email protected]; Romina Fornes - [email protected]; Daniela Fernandois - [email protected]; Maritza P Garrido - [email protected]; Monika Greiner - [email protected]; Hernan E Lara - [email protected]; Alfonso H Paredes* - [email protected] * Corresponding author
Published: 16 June 2009 Reproductive Biology and Endocrinology 2009, 7:64
doi:10.1186/1477-7827-7-64
Received: 5 March 2009 Accepted: 16 June 2009
This article is available from: http://www.rbej.com/content/7/1/64 © 2009 Acuña et al; licensee BioMed Central Ltd. 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.
Abstract Background: Depletion of ovarian follicles is associated with the end of reproductive function in ageing females. Recently, it has been described that this process parallels increases in the concentration of norepinephrine (NE) in the rat ovary. In sexually mature rats, experimentallyinduced increases in the sympathetic tone of the ovary is causally related to ovarian cyst formation and deranged follicular development. Thus, there is a possibility that increased ovarian NE concentrations represent changes in the activity of sympathetic nerves, which consequently participate in the process of ovarian cyst formation observed during ageing in the human and experimental animal models. Methods: Sprague-Dawley rats between 6 and 14 months old were used to analyse the capacity of the ovary to release 3H-NE recently incorporated under transmural depolarisation in relation to changes in the ovarian follicular population. Morphometric analysis of ovarian follicles and real time PCR for Bcl2 and Bax mRNA were used to assess follicular atresia. Results: From 8 months old, the induced release of recently incorporated 3H-norepinephrine (3HNE) from the ovary and ovarian NE concentrations increased, reaching their peak values at 12 months old and remained elevated up to 14 months old. Increases in sympathetic nerve activity paralleled changes in the follicular population, as well as disappearance of the corpus luteum. In contrast, luteinised follicles, precystic follicles, and cystic follicles increased. During this period, the relationship between Bax and Bcl2 mRNAs (the proapoptotic/antiapoptotic signals) increased, suggesting atresia as the principal mechanism contributing to the decreased follicular population. When NE tone was increased, the mRNA ratio favoured Bcl2 to Bax a
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