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Altered levels of mRNA expression and pharmacological reactivity of α 1 ‐adrenergic receptor subtypes in the late‐pregnant rat myometrium
Author(s) -
Ducza Eszter,
Gáspár Róbert,
Falkay George
Publication year - 2002
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.10148
Subject(s) - biology , endocrinology , myometrium , medicine , messenger rna , receptor , antagonist , contractility , adrenergic antagonist , gene expression , uterus , gene , biochemistry
The adrenergic system plays a major role in the regulation of the uterine contractility during pregnancy. Our previous studies have shown the significance of the α 1 ‐adrenergic receptors (ARs) in the control of pregnant uterine contractility both in vitro and in vivo. Our present aim was to determine the changes in mRNA expression and pharmacological reactivity of the α 1 ‐ARs on days 18, 20, and 22 of pregnancy. To demonstrate the expressions of α 1 ‐AR subtype mRNA, we used a reverse transcription‐polymerase chain reaction (RT‐PCR); the pharmacological reactivity was tested by electric field stimulation (EFS). The expression of α 1A ‐AR mRNA increased from day 18 to 22, while no α 1B ‐AR mRNA was detectable. We found a small increase in the expression of α 1D ‐AR mRNA on day 20, which was not followed by a significant change in pharmacological reactivity. The α 1D ‐receptor expression and pharmacological reactivity decreased significantly up to day 22. EFS studies revealed that the α 1A ‐AR antagonist 5‐methylurapidil had EC50 values (1.9 × 10 −6 –6.3 × 10 −6 M) about one order of magnitude lower than those of the α 1D ‐AR antagonist BMY 7378 (4 × 10 −6 –3.6 × 10 −5 M). However, the α 1B ‐AR antagonist cyclazosine exerted only a slight effect on the stimulated contractions. Strong correlations were found between the α 1A ‐mRNA expression and the EC50 of 5‐methylurapidil (r 2 =0.9712), and between the α 1D ‐AR mRNA expression and the EC50 of BMY 7378 (r 2 = 0.9937). Our findings suggest that both α 1A ‐ and α 1D ‐ARs are involved in the regulation of the pregnant uterine contractility. The density and pharmacological reactivity indicate that the α 1A ‐AR seems to play the major role in late‐pregnant myometrial contraction. Mol. Reprod. Dev. 62: 343–347, 2002. © 2002 Wiley‐Liss, Inc.