Studies of the role of steroid hormone in the regulation of oocyte maturation in cattle
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Studies of the role of steroid hormone in the regulation of oocyte maturation in cattle Hai Feng Wang, Naoki Isobe, Kanako Kumamoto, Hideaki Yamashiro, Yasuhisa Yamashita and Takato Terada* Address: Laboratory of Animal Reproduction, Graduate School of Biosphere Sciences, Hiroshima University, Higashi-Hiroshima, 739-8528, Japan Email: Hai Feng Wang - [email protected]; Naoki Isobe - [email protected]; Kanako Kumamoto - [email protected]; Hideaki Yamashiro - [email protected]; Yasuhisa Yamashita - [email protected]; Takato Terada* - [email protected] * Corresponding author
Published: 03 February 2006 Reproductive Biology and Endocrinology2006, 4:4
doi:10.1186/1477-7827-4-4
Received: 05 November 2005 Accepted: 03 February 2006
This article is available from: http://www.rbej.com/content/4/1/4 © 2006Wang 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: The objective of this study was to investigate whether the steroid hormone(s) secreted from cumulus-oocyte complexes (COCs) is a prerequisite for bovine oocyte maturation and cumulus expansion using aminoglutethimide (AGT), a P450 cholesterol side-chain cleavage inhibitor. Methods: In experiment 1, COCs were cultured in maturation medium with various concentrations of AGT for 22 h to determine the effective concentration of AGT to inhibit steroid hormone secretion, meiotic maturation and cumulus expansion. In experiment 2, COCs were cultured in conditioned medium (CM) and TCM-199 medium with or without 10 mM AGT to check whether steroid hormones secreted from COCs were responsible for oocyte maturation and cumulus expansion. Experiments 3 and 4 were carried out to determine whether exogenous progesterone or estradiol-17beta was able to overcome the inhibitory effects of AGT on oocytes maturation and cumulus expansion. COCs cultured in 10 mM AGTcontaining medium supplemented with various concentrations of progesterone or estradiol-17beta for 22 h were examined for oocyte maturation and cumulus expansion. Results: Experiment 1 showed that a concentration of 10 mM AGT in medium was sufficient to block steroid hormone secretion, oocyte maturation and cumulus expansion, and that these inhibitory effects were fully reversible. In experiment 2, the addition of 10 mM AGT to CM did not significantly prevent oocyte maturation and cumulus expansion, implying that CM contains the steroid hormone(s) secreted from COCs, which are closely associated with oocyte maturation and cumulus expansion. The results in experiments 3 and 4 demonstrated that the addition of any concentration of progesterone or estradiol17beta in the medium did not reduce the inhibitory effects of AGT on oocyte maturation and cumulus expansion. Conclusion: Our
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