Subpopulations of corticotrophs in the sheep pituitary during late gestation: Effects of development and placental restriction

Farrand, Kirsten, McMillen, I. Caroline, Tanaka, Shigeyasu and Schwartz, Jeffrey (2006) Subpopulations of corticotrophs in the sheep pituitary during late gestation: Effects of development and placental restriction. Endocrinology, 147 10: 4762-4771. doi:10.1210/en.2005-1522


Author Farrand, Kirsten
McMillen, I. Caroline
Tanaka, Shigeyasu
Schwartz, Jeffrey
Title Subpopulations of corticotrophs in the sheep pituitary during late gestation: Effects of development and placental restriction
Journal name Endocrinology   Check publisher's open access policy
ISSN 0013-7227
1945-7170
Publication date 2006
Sub-type Article (original research)
DOI 10.1210/en.2005-1522
Volume 147
Issue 10
Start page 4762
End page 4771
Total pages 10
Place of publication Bethesda, MA, United States
Publisher Endocrine Society
Language eng
Abstract The prepartum surge in fetal plasma cortisol is essential for the normal timing of parturition in sheep and may result from an increase in the ratio of ACTH to proopiomelanocortin (POMC) in the fetal circulation. In fetuses subjected to experimental induction of placental restriction, the prepartum surge in fetal cortisol is exaggerated, whereas pituitary POMC mRNA levels are decreased, and in vitro, unstimulated ACTH secretion is elevated in corticotrophs nonresponsive to CRH. We therefore investigated the changes in the relative proportions of cells expressing POMC, ACTH, and the CRH type 1 receptor (CRHR1) shortly before birth and during chronic placental insufficiency. Placental restriction (PR) was induced by removal of the majority of placental attachment sites in five ewes before mating. Pituitaries were collected from control and PR fetal sheep at 140 d (control, n = 4; PR, n = 4) and 144 d (control, n = 6; PR, n = 4). Pituitary sections were labeled with specific antisera raised against POMC, ACTH, and CRHR1. Three major subpopulations of corticotrophs were identified that expressed POMC + ACTH + CRHR1, ACTH + CRHR1, or POMC only. The proportion of pituitary corticotrophs expressing POMC + ACTH + CRHR1 decreased (P < 0.05) between 140 (control, 60 +/- 1%; PR, 66 +/- 4%) and 144 (control, 45 +/- 2%; PR, 56 +/- 6%) d. A significantly higher (P < 0.05) proportion of corticotrophs expressed POMC + ACTH + CRHR1 in the pituitary of the PR group compared with controls. This study is the first to demonstrate subpopulations of corticotrophs in the fetal sheep pituitary that differentially express POMC, ACTH, and CRHR1 and the separate effects of gestational age and placental restriction on these subpopulations of corticotrophs.
Keyword Endocrinology & Metabolism
Ovine Fetal Pituitary
Anterior-pituitary
Arginine-vasopressin
In-vitro
Adrenocorticotropin Secretion
Monoclonal-antibodies
Acth Precursors
Hormone-binding
Target-cells
Proopiomelanocortin
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Biomedical Sciences Publications
 
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Created: Mon, 13 Aug 2007, 16:32:33 EST