Increased expression of connexin-43 in the rat myometrium during labor is associated with an increase in the plasma estrogemprogesterone ratio

Stephen J. Lye, Bruce J. Nicholson, Mariola Mascarenhas, Leslie Mackenzie, Teresa Petrocelli

Research output: Contribution to journalArticle

139 Scopus citations

Abstract

The molecular mechanisms that regulate the synthesis of the myométrial gap junction protein, connexin-43 (Cx-43), are controversial. We measured myométrial Cx-43 messenger RNA, protein and gap junction frequency, and area in myométrial samples collected from nonpregnant rats and pregnant rats at days 5, 10, 15, 17, 18, 19, 20, 21, 22, 23 (during delivery), and 1 day postpartum and correlated these data with plasma concentrations of estradiol 17β and progesterone. Cx-43 transcripts were low or undetectable (connexin-43:glyceraldehyde phosphate dehydrogenase ratio <0.2) in nonpregnant rats or in rats before day 10 of pregnancy. Transcripts rose to 0.52 ± 0.11 on day 10, increased (2.9-fold) to 1.51 ± 0.48 on day 22, and increased a further 2.9-fold to maximal levels of 4.42 ± 0.67 during labor. Cx-43 protein was barely detectable on day 21 [0.12 ± 0.04 relative optical density (ROD) units], increased 2.5-fold on day 22 (0.30 ± 0.04 ROD units), and a further 3.7-fold during delivery (1.10 ± 0.15 ROD units), at a time when gap junctions were present in large numbers in the cell membrane. Between day 21 and delivery the increase in Cx-43 transcripts (8.2-fold) and protein (9.2-fold) were of a similar magnitude. There was a significant positive correlation between the increases in Cx-43 transcripts and the increase in the ratio of plasma estradiol to progesterone. Levels of Cx-43 transcripts, protein, and gap junctions fell rapidly postpartum. Our data demonstrate: 1) that transcripts encoding the gap junction protein, Cx-43, are at maximal levels during delivery and that this increase is temporally associated with increases in Cx-43 protein and the appearance of gap junctions; and 2) that these data, in association with changes in plasma steroid concentrations, are consistent with myometrial Cx-43 transcript levels being regulated positively by estrogen and negatively by progesterone during pregnancy.

Original languageEnglish (US)
Pages (from-to)2380-2386
Number of pages7
JournalEndocrinology
Volume132
Issue number6
DOIs
StatePublished - Jun 1993
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology

Fingerprint Dive into the research topics of 'Increased expression of connexin-43 in the rat myometrium during labor is associated with an increase in the plasma estrogemprogesterone ratio'. Together they form a unique fingerprint.

  • Cite this