title: Downregulation of adrenal atrial natriuretic peptide receptor mRNAs and proteins by pregnancy in rats.
abstract: The main objective of this study was to find out if the reported changes in the aldosterone-suppressant activity of atrial natriuretic peptide (ANP) during different hormonal states in rats are due to a modulation of ANP receptors. In zona glomerulosa cells, ribonuclease protection assay detected mRNAs for guanylate cyclase (GC)-coupled ANP GC-A and GC-B receptors, and for ANP C receptors, which are not coupled to GC. Western analysis using polyclonal anti-GC-A and anti-GC-B receptor antibodies revealed the presence of GC-A but not GC-B receptor proteins in zona glomerulosa cells. Pregnancy (days 7, 16 and 21), oestradiol-17 beta and progesterone decreased mRNAs for all the three ANP receptors in zona glomerulosa cells. Pregnancy decreased GC-A receptor proteins in zona glomerulosa cells, but these recovered to virgin values on day 2 postpartum. ANP receptor mRNAs in zona glomerulosa cells increased by postpartum day 2, but did not reach the values found in virgin rats. Zona fasciculata mainly contained GC-A receptor mRNA. It is concluded that ANP receptors in rat adrenal zona glomerulosa are modulated by pregnancy, oestrogen and progesterone; a decrease in ANP GC-A receptors during pregnancy might explain the accompanying decrease in the aldosterone-suppressant effects of ANP.
authors.affiliation: Department of Physiology, McGill University, Montreal, Quebec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Vaillancourt
authors.forename: S
authors.initials: S
authors.lastname: Omer
authors.forename: R
authors.initials: R
authors.lastname: Palfree
authors.forename: D R
authors.initials: DR
authors.lastname: Varma
authors.forename: S
authors.initials: S
authors.lastname: Mulay
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006162:Guanylate Cyclase / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism*; D015384:Zona Glomerulosa / Q000378:metabolism*
chemical_list: D011374:Progesterone; D004958:Estradiol; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor