Assessment of myometrial concentrations of oestrogen and progesterone receptors in the lower uterine segment of full-term pregnancies in presence or absence of labour.

Joana Soares De Arruda,Edward Araujo Júnior,Manuel De Jesus Simões,Luiz Kulay Júnior

doi:10.1155/2013/213193

Joana Soares De Arruda, Edward Araujo Júnior + Show 2 more

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https://doi.org/10.1155/2013/213193

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Journal: Journal of Pregnancy	Publication Date: Jan 1, 2013
Citations: 9	License type: CC BY 3.0

Affiliation: Universidade Federal de São Paulo

Abstract

Objective. To assess the concentration of progesterone (PRs) and oestrogen (ORs) receptors of myometrium of full-term pregnant women in the myometrium of lower segment of the uterus in relationship with presence or absence of labour. Methods. This was a cross-sectional prospective study with 21 pregnant women, being 6 in labour (Group I) and 15 without labour (Group II). The biopsy of myometrium was realized during caesarian section, and the excised tissue was stained using immunohistochemical techniques for the quantification of the receptors, and with the aid of image-analysis software, the numbers of receptors for each hormone were determined spectrophotometrically. The Mann-Whitney test was used to compare the pregnant women in each study group with respect to the numbers of ORs and PRs. The Wilcoxon test was used to compare the concentration of ORs and PRs in each group separately. Results. The mean of gestational age was 39 weeks, (range, 37 to 41 weeks). The medians of PRs and ORs in pregnant women in labour (Group I) were 29.3 (range, 24.6–30.2) and 32.3 (range, 22.9–49.0), respectively. The medians of PRs and ORs in pregnant women without labour (Group II) were 43.6 (range, 23.6–70) and 43.9 (range, 18.3–62.6), respectively. We did not observe significant differences of the number of ORs and PRs in both groups (P = 0.13 and 0.37, resp.). The number of ORs was statistically more than that of PRs in Group II (Z calculated = 16.00). Conclusion. The concentrations of PRs and ORs were similar in the myometrium of the lower uterine segment of pregnant women during and without labour, but the concentration of ORs was more than that of PRs in the myometrium of the lower uterine segment of pregnant women without labour.

Highlights

Hormonal changes at the moment of parturition may constitute an important regulatory mechanism for myometrial contraction
We observed that the progesterone receptors (PRs) and oestrogen receptors (ORs) concentrations were smaller in the myometrium of lower uterine segment of Group I, and these concentrations were higher in Group II (Group I r calculated = 0.49 versus Group II r calculated = 0.74) (Table 2)
Recent works have suggested that a decrease in the number of progesterone B receptors, favouring an increase in the expression of progesterone receptor A, results in a triggering of the mechanism that initiates labour [5,6,7, 9, 10]

Summary

Introduction

Hormonal changes at the moment of parturition may constitute an important regulatory mechanism for myometrial contraction. This genetic mechanism may lead to the attenuation of progesterone’s effects by, for example, a specific gene that interrupts its Journal of Pregnancy action at a molecular, biochemical, and/or cellular level [1] Corroborating these studies in a review, Mendelson postulates that an increase in inflammatory response occurs as a result of the activation of the nuclear factor (kappa) beta, leading to uterine contractility in two ways: (1) the direct activation of contractile genes (e.g., COX-2, oxytocin receptors, and connexin 43) and (2) a blockade of the ability of progesterone receptors (PRs) to maintain uterine quiescence [5]

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Conclusion