Corticotropin-releasing hormone is produced by rat corticotropes and modulates ACTH secretion in a paracrine/autocrine fashion

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Abstract

Anterior pituitary hormone secretion is mainly regulated by hypothalamic releasing factors, which reach the pituitary via portal vessels. It has been demonstrated recently that these peptides can also be produced by the pituitary itself, thus possibly modulating hormone secretion in a paracrine/autocrine fashion. The object of this study was to seek evidence for the synthesis and secretion of corticotropin-releasing hormone (CRH) within the anterior pituitary and to ascertain its biological relevance. Messenger RNA from adult rat anterior pituitary fragments and cell cultures was reverse transcribed and subjected to PCR amplification using primers specific to the rat CRH gene. As in the hypothalamus, a single 232-bp band was obtained. The correspondence of the amplified fragment to the sequence of the CRH gene was confirmed by Southern blotting and restriction enzyme digestion. Combined in situ reverse transcription-PCR amplification/immunocytochemistry demonstrated the presence of CRH mRNA in corticotropes. Medium from anterior pituitary primary cultures contained ~ 7 pg/μg protein of CRH immunoreactivity which presented the same chromatographic profile on HPLC as the mature CRH peptide. Incubation of anterior pituitary cells with an antibody directed against CRH markedly reduced basal ACTH secretion compared with serum-treated control wells (0.89 ± 0.11 vs 1.74 ± 0.14 ng/200,000 cells in control wells after 1 h, P <0.05; 1.17 ± 0.10 vs. 2.16 ± 0.39 ng/200,000 cells after 2 h, P <0.05; 1.45 ± 0.12 vs. 3.12 ± 0.61 ng/200,000 cells after 3 h, P <0.05). Further, the ACTH response to potassium and to forskolin was markedly blunted by the CRH antiserum as well as by the CRH antagonist, α-helical CRH (9-41). In conclusion, this study demonstrates the presence of CRH mRNA in normal rat corticotropes and the secretion of the mature peptide by the anterior pituitary, pointing to the production of CRH at the site of its target cells. In addition, intrapituitary CRH contributes in a paracrine/autocrine fashion to ACTH secretion.

Original languageEnglish
Pages (from-to)2478-2484
Number of pages7
JournalJournal of Clinical Investigation
Volume101
Issue number11
Publication statusPublished - Jun 1 1998

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Corticotropin-Releasing Hormone
Adrenocorticotropic Hormone
Messenger RNA
Peptides
Anterior Pituitary Hormones
Pituitary Hormone-Releasing Hormones
Hormone Antagonists
Polymerase Chain Reaction
Colforsin
Southern Blotting
Genes
Hypothalamus
Reverse Transcription
Immune Sera
Digestion
Potassium
Cell Culture Techniques
Immunohistochemistry
High Pressure Liquid Chromatography
Hormones

Keywords

  • Corticotropes
  • Gene expression
  • Hypothalamic releasing factors
  • Tissue distribution

ASJC Scopus subject areas

  • Medicine(all)

Cite this

@article{a44dfcf21b894dd69a21ecf76f04b4c3,
title = "Corticotropin-releasing hormone is produced by rat corticotropes and modulates ACTH secretion in a paracrine/autocrine fashion",
abstract = "Anterior pituitary hormone secretion is mainly regulated by hypothalamic releasing factors, which reach the pituitary via portal vessels. It has been demonstrated recently that these peptides can also be produced by the pituitary itself, thus possibly modulating hormone secretion in a paracrine/autocrine fashion. The object of this study was to seek evidence for the synthesis and secretion of corticotropin-releasing hormone (CRH) within the anterior pituitary and to ascertain its biological relevance. Messenger RNA from adult rat anterior pituitary fragments and cell cultures was reverse transcribed and subjected to PCR amplification using primers specific to the rat CRH gene. As in the hypothalamus, a single 232-bp band was obtained. The correspondence of the amplified fragment to the sequence of the CRH gene was confirmed by Southern blotting and restriction enzyme digestion. Combined in situ reverse transcription-PCR amplification/immunocytochemistry demonstrated the presence of CRH mRNA in corticotropes. Medium from anterior pituitary primary cultures contained ~ 7 pg/μg protein of CRH immunoreactivity which presented the same chromatographic profile on HPLC as the mature CRH peptide. Incubation of anterior pituitary cells with an antibody directed against CRH markedly reduced basal ACTH secretion compared with serum-treated control wells (0.89 ± 0.11 vs 1.74 ± 0.14 ng/200,000 cells in control wells after 1 h, P <0.05; 1.17 ± 0.10 vs. 2.16 ± 0.39 ng/200,000 cells after 2 h, P <0.05; 1.45 ± 0.12 vs. 3.12 ± 0.61 ng/200,000 cells after 3 h, P <0.05). Further, the ACTH response to potassium and to forskolin was markedly blunted by the CRH antiserum as well as by the CRH antagonist, α-helical CRH (9-41). In conclusion, this study demonstrates the presence of CRH mRNA in normal rat corticotropes and the secretion of the mature peptide by the anterior pituitary, pointing to the production of CRH at the site of its target cells. In addition, intrapituitary CRH contributes in a paracrine/autocrine fashion to ACTH secretion.",
keywords = "Corticotropes, Gene expression, Hypothalamic releasing factors, Tissue distribution",
author = "Giraldi, {Francesca Pecori} and Francesco Cavagnini",
year = "1998",
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volume = "101",
pages = "2478--2484",
journal = "Journal of Clinical Investigation",
issn = "0021-9738",
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T1 - Corticotropin-releasing hormone is produced by rat corticotropes and modulates ACTH secretion in a paracrine/autocrine fashion

AU - Giraldi, Francesca Pecori

AU - Cavagnini, Francesco

PY - 1998/6/1

Y1 - 1998/6/1

N2 - Anterior pituitary hormone secretion is mainly regulated by hypothalamic releasing factors, which reach the pituitary via portal vessels. It has been demonstrated recently that these peptides can also be produced by the pituitary itself, thus possibly modulating hormone secretion in a paracrine/autocrine fashion. The object of this study was to seek evidence for the synthesis and secretion of corticotropin-releasing hormone (CRH) within the anterior pituitary and to ascertain its biological relevance. Messenger RNA from adult rat anterior pituitary fragments and cell cultures was reverse transcribed and subjected to PCR amplification using primers specific to the rat CRH gene. As in the hypothalamus, a single 232-bp band was obtained. The correspondence of the amplified fragment to the sequence of the CRH gene was confirmed by Southern blotting and restriction enzyme digestion. Combined in situ reverse transcription-PCR amplification/immunocytochemistry demonstrated the presence of CRH mRNA in corticotropes. Medium from anterior pituitary primary cultures contained ~ 7 pg/μg protein of CRH immunoreactivity which presented the same chromatographic profile on HPLC as the mature CRH peptide. Incubation of anterior pituitary cells with an antibody directed against CRH markedly reduced basal ACTH secretion compared with serum-treated control wells (0.89 ± 0.11 vs 1.74 ± 0.14 ng/200,000 cells in control wells after 1 h, P <0.05; 1.17 ± 0.10 vs. 2.16 ± 0.39 ng/200,000 cells after 2 h, P <0.05; 1.45 ± 0.12 vs. 3.12 ± 0.61 ng/200,000 cells after 3 h, P <0.05). Further, the ACTH response to potassium and to forskolin was markedly blunted by the CRH antiserum as well as by the CRH antagonist, α-helical CRH (9-41). In conclusion, this study demonstrates the presence of CRH mRNA in normal rat corticotropes and the secretion of the mature peptide by the anterior pituitary, pointing to the production of CRH at the site of its target cells. In addition, intrapituitary CRH contributes in a paracrine/autocrine fashion to ACTH secretion.

AB - Anterior pituitary hormone secretion is mainly regulated by hypothalamic releasing factors, which reach the pituitary via portal vessels. It has been demonstrated recently that these peptides can also be produced by the pituitary itself, thus possibly modulating hormone secretion in a paracrine/autocrine fashion. The object of this study was to seek evidence for the synthesis and secretion of corticotropin-releasing hormone (CRH) within the anterior pituitary and to ascertain its biological relevance. Messenger RNA from adult rat anterior pituitary fragments and cell cultures was reverse transcribed and subjected to PCR amplification using primers specific to the rat CRH gene. As in the hypothalamus, a single 232-bp band was obtained. The correspondence of the amplified fragment to the sequence of the CRH gene was confirmed by Southern blotting and restriction enzyme digestion. Combined in situ reverse transcription-PCR amplification/immunocytochemistry demonstrated the presence of CRH mRNA in corticotropes. Medium from anterior pituitary primary cultures contained ~ 7 pg/μg protein of CRH immunoreactivity which presented the same chromatographic profile on HPLC as the mature CRH peptide. Incubation of anterior pituitary cells with an antibody directed against CRH markedly reduced basal ACTH secretion compared with serum-treated control wells (0.89 ± 0.11 vs 1.74 ± 0.14 ng/200,000 cells in control wells after 1 h, P <0.05; 1.17 ± 0.10 vs. 2.16 ± 0.39 ng/200,000 cells after 2 h, P <0.05; 1.45 ± 0.12 vs. 3.12 ± 0.61 ng/200,000 cells after 3 h, P <0.05). Further, the ACTH response to potassium and to forskolin was markedly blunted by the CRH antiserum as well as by the CRH antagonist, α-helical CRH (9-41). In conclusion, this study demonstrates the presence of CRH mRNA in normal rat corticotropes and the secretion of the mature peptide by the anterior pituitary, pointing to the production of CRH at the site of its target cells. In addition, intrapituitary CRH contributes in a paracrine/autocrine fashion to ACTH secretion.

KW - Corticotropes

KW - Gene expression

KW - Hypothalamic releasing factors

KW - Tissue distribution

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