HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Fjeldheim, A.-K. Articles by Gautvik, K. M Search for Related Content PubMed PubMed Citation Articles by Fjeldheim, A.-K. Articles by Gautvik, K. M

Thyrotrophin-releasing hormone receptor 1 and prothyrotrophin-releasing hormone mRNA expression in the central nervous system are regulated by suckling in lactating rats

¹ Institute of Basic Medical Science, Department of Biochemistry, University of Oslo, PO Box 1112 Blindern, N-0317 Oslo, Norway, ² Department of Clinical Pharmacology, Rikshospitalet University Hospital, N-0027 Oslo, Norway, ³ Department of Physiology, University of Oslo, PO Box 1103 Blindern, N-0317 Oslo, Norway, ⁴ Department of Molecular Biosciences, University of Oslo, PO Box 1041 Blindern, N-0316 Oslo, Norway and ⁵ Department of Clinical Chemistry, Ullevål University Hospital, N-0407 Oslo, Norway

(Correspondence should be addressed to K M Gautvik, Institute of Basic Medical Science, Department of Biochemistry, University of Oslo, PO Box 1112 Blindern, N-0317 Oslo, Norway; Email: k.m.gautvik{at}medisin.uio.no)

Background: The accepted function of the hypothalamic peptide, thyrotrophin-releasing hormone (TRH), is to initiate release of thyrotrophin (TSH) from the pituitary. A physiological role for TRH in lactating rats has not yet been established.

Methods: Tissues were prepared from random-cycling and lactating rats and analysed using Northern blot, real time RT-PCR and quantitative in situ hybridisation.

Results: This study demonstrates that TRH receptor 1 (TRHR1) mRNA expression is up-regulated in the pituitary and in discrete nuclei of the hypothalamus in lactating rats, while proTRH mRNA expression levels are increased only in the hypothalamus. The results were corroborated by quantitative in situ analysis of proTRH and TRHR1. Bromocriptine, which reduced prolactin (PRL) concentrations in plasma of lactating and nursing rats, also counteracted the suckling-induced increase in TRHR1 mRNA expression in the hypothalamus, but had an opposite effect in the pituitary. These changes were confined to the hypothalamus and the amygdala in the brain.

Conclusions: The present study shows that the mechanisms of suckling-induced lactation involve region-specific regulation of TRHR1 and proTRH mRNAs in the central nervous system notably at the hypothalamic level. The results demonstrate that continued suckling is critical to maintain plasma prolactin (PRL) levels as well as proTRH and TRHR1 mRNA expression in the hypothalamus. Increased plasma PRL levels may have a positive modulatory role on the proTRH/TRHR1 system during suckling.

This article has been cited by other articles:

				M. Yamada, N. Shibusawa, S. Ishii, K. Horiguchi, R. Umezawa, K. Hashimoto, T. Monden, T. Satoh, J. Hirato, and M. Mori Prolactin Secretion in Mice with Thyrotropin-Releasing Hormone Deficiency Endocrinology, May 1, 2006; 147(5): 2591 - 2596. [Abstract] [Full Text] [PDF]