Reduced Expression of Immunoreactive β2-Adrenergic Receptor Protein in Human Myometrium with Labor

Boonsri Chanrachakul, Balwir Matharoo-Ball, Anita Turner, Graham Robinson, Fiona Broughton-Pipkin, Sabaratnam Arulkumaran, Raheela N. Khan

Research output: Contribution to journalArticlepeer-review

Abstract

A considerable body of evidence exists suggesting that the β 2-adrenergic receptor (β2-AR) mediates uterine relaxation. However, little information exists on the localization, distribution, or expression of β2-ARs in the human myometrium during the nonpregnant to labor transition. We have used immunochemical methods to investigate β2-AR localization and expression in the nonpregnant, term pregnant, and term parturient uterus. Myometrial biopsies were obtained from 1) nonpregnant, menstruating women undergoing hysterectomy; 2) singleton term pregnant women undergoing elective cesarean section before the onset of labor; or 3) singleton term pregnant women undergoing emergency cesarean section after spontaneous labor. Tissues were processed for immunohistochemistry, immunofluorescence, and Western blotting and a primary polyclonal antibody specific to the human β2-AR to identify immunoreactive myometrial β2-AR. Protein levels were subsequently quantified by densitometry relative to rat brain protein. Immunohistochemistry and immunofluorescence demonstrated the presence of β2-AR predominantly at the plasma membrane and also in the cytosol of myometrial cells. A 2-fold decrease in protein levels of the β2-AR was apparent in the myometrium of labor compared with that of nonpregnant and pregnant nonlaboring women (P < 0.05). These results demonstrate that down-regulation of β2-AR protein with labor may constitute a contributory mechanism by which uterine quiescence is removed at term.

Original languageEnglish
Pages (from-to)4997-5001
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Volume88
Issue number10
DOIs
Publication statusPublished - Oct 2003

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