Calcitriol affects hCG gene transcription in cultured human syncytiotrophoblasts
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BioMed Central
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Calcitriol affects hCG gene transcription in cultured human syncytiotrophoblasts David Barrera, Euclides Avila, Guillermo Hernández, Isabel Méndez, Leticia González, Ali Halhali, Fernando Larrea, Angélica Morales and Lorenza Díaz* Address: Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga No. 15, Tlalpan 14000, México, D.F; México Email: David Barrera - [email protected]; Euclides Avila - [email protected]; Guillermo Hernández - [email protected]; Isabel Méndez - [email protected]; Leticia González - [email protected]; Ali Halhali - [email protected]; Fernando Larrea - [email protected]; Angélica Morales - [email protected]; Lorenza Díaz* - [email protected] * Corresponding author
Published: 22 January 2008 Reproductive Biology and Endocrinology 2008, 6:3
doi:10.1186/1477-7827-6-3
Received: 16 November 2007 Accepted: 22 January 2008
This article is available from: http://www.rbej.com/content/6/1/3 © 2008 Barrera 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: In pregnancy, maternal serum concentrations of calcitriol significantly rise as a result of increased renal and placental contribution in order to assure calcium supply for the developing fetus. Considering that placenta is a site for vitamin D activation, and the versatility and potency of calcitriol, it is feasible that this hormone participates in fetal/placental development and physiology. In the present work we studied calcitriol actions upon human chorionic gonadotropin (hCG) secretion and expression in cultured trophoblasts, as well as vitamin D receptor (VDR) and CYP27B1 immunolocalization in placental villi. Methods: Quantification of hCG in culture media was performed by immunoassay. Expression studies were carried out by real time PCR. Analysis of CYP27B1 and VDR localization in placental slides were performed by immunohistochemistry. Statistical significance was established by one way ANOVA using Tukey test for comparisons. Results: Calcitriol regulated hCG in a time-dependent manner: at 6 h the secosteroid stimulated hCG, whereas longer incubations (24 h) showed opposite effects. Interestingly, calcitriol stimulatory effects on hCG were accompanied by an increase in intracellular cAMP content and were abolished by pre-incubation of the cells with a selective protein kinase A inhibitor. Immunohistochemical techniques showed differential VDR localization in the syncytiotrophoblast layer or in the vascular smooth muscle cells depending on the epitope to which the antibodies were raised (specific for the carboxy- or amino-terminal regions, respectively). CYP27B1 was immunolocalized in the syncytiotrophoblast layer
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