Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour
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Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour Binhai Cong†1, Lanmei Zhang†2, Lu Gao1 and Xin Ni*1 Address: 1Department of Physiology, Second Military Medical University, Shanghai 200433, PR China and 2Department of Gynecology and Obstetric, Navy General Hospital, Beijing 10037, PR China Email: Binhai Cong - [email protected]; Lanmei Zhang - [email protected]; Lu Gao - [email protected]; Xin Ni* - [email protected] * Corresponding author †Equal contributors
Published: 12 May 2009 Reproductive Biology and Endocrinology 2009, 7:43
doi:10.1186/1477-7827-7-43
Received: 25 March 2009 Accepted: 12 May 2009
This article is available from: http://www.rbej.com/content/7/1/43 © 2009 Cong 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: Corticotropin-releasing hormone (CRH) and CRH-related peptide are shown to modulate uterine contractility through two CRH receptor subtype, CRH-R1 and CRH-R2 during pregnancy. Through different signaling pathways, CRH-R1 maintains myometrial quiescence whereas CRH-R2 promotes smooth muscle contractility. We hypothesized that the expression of CRH receptors in myometrium might be changed during pregnancy and labour. Method: Immunohistochemistry, Western blot and RT-PCR were used to quantify the cellular localization, the protein levels and the mRNA variants of both CRH-R1 and CRH-R2 in upper segment (US) and lower segment (LS) myometrium from nonpregnant and pregnant women at term before or after labour. Results: CRH-R1 and CRH-R2 were predominately localized to myometrial smooth muscle cells in US and LS. The protein level of CRH-R1 in US was significantly down-regulated in pregnancy, with a further decrease at the onset of labour. However, the expression of CRH-R1 in LS remained unchanged during pregnancy and labour. No significant changes in CRH-R2 expression were observed in US or LS. Six variants of CRH-R1, CRH-R1alpha,-R1beta,-R1c, -R1e,-R1f and -R1g, were identified in nonpregnant and pregnant myometrium. CRH-R2alpha was identified in pregnant myometrium, whereas CRH-R2beta was identified in nonpregnant myometrium Conclusion: CRH-R1 and CRH-R2 are expressed in nonpregnant and pregnant US and LS myometrium. Changed expression of CRH receptors during labour may underlie the initiation of uterine contractility during parturition.
Background During pregnancy and labour the uterus undergoes dramatic changes in its contractile activity, which requires functional differentiation of the different regions of uterus. The upper segment (US) region of the uterus maintains a relaxatory phenotype throughout most of gestation to accommodate the growing fetus and adopts a contrac-
tile phenotype to cause expulsion of fetus at
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