This Article Full Text Full Text (PDF) All Versions of this Article: 149/5/2313    most recent Author Manuscript (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Google Scholar Articles by Janssens, K. Articles by Denef, C. PubMed PubMed Citation Articles by Janssens, K. Articles by Denef, C.

β₁-Adrenoceptor Expression in Rat Anterior Pituitary Gonadotrophs and in Mouse T3-1 and LβT2 Gonadotrophic Cell Lines

Laboratory of Cell Pharmacology, University of Leuven, Medical School, Gasthuisberg, B-3000 Leuven, Belgium

Address all correspondence and requests for reprints to: Professor Carl Denef, Laboratory of Cell Pharmacology, University of Leuven, Medical School, Campus Gasthuisberg (O & N), B-3000 Leuven, Belgium. E-mail: Carl.Denef{at}med.kuleuven.be.

The rat anterior pituitary expresses β₂-adrenoceptors (ARs) on somatotrophs, lactotrophs, and corticotrophs. The present study investigates whether β₁-ARs exist in the anterior pituitary, in which cell type(s) they are found, and whether they are regulated by glucocorticoids. As determined by quantitative RT-PCR and Western immunoblotting, the rat anterior pituitary expressed β₁-AR mRNA and protein. Unlike the β₂-AR, expression decreased to very low levels after 5-d aggregate cell culture but was strongly up-regulated in a dose- and time-dependent manner by dexamethasone (DEX). Glucocorticoids attenuated isoproterenol-induced down-regulation of β₁-AR mRNA levels. As examined by immunofluorescence confocal microscopy, β₁-AR immunoreactivity was detected in a subpopulation of gonadotrophs, but not in somatotrophs, lactotrophs, corticotrophs, thyrotrophs, or folliculo-stellate cells. β₁-AR-immunoreactivity cells were often surrounded by cup-shaped lactotrophs. Consistent with these findings, β₁-AR mRNA was considerably more abundant in the gonadotrophic T3-1 and LβT2 cell lines than in the GHFT, GH3, and TtT/GF cell lines. DEX did not affect expression level in the cell lines. DEX also failed to up-regulate β₁-AR mRNA levels in aggregates from a subpopulation enriched in large gonadotrophs obtained by gradient sedimentation. In contrast, excessive DEX-dependent up-regulation of β₁-AR mRNA was found in a subpopulation enriched in small nonhormonal cells. The present data indicate that β₁-AR is expressed in a subpopulation of gonadotrophs with a topographical relationship to lactotrophs. However, the glucocorticoid-induced up-regulation does not seem to occur directly in the gonadotrophs but within (an)other unidentified cell type(s), or is transduced by that cell type on gonadotrophs.

This article has been cited by other articles:

				K. Janssens, M. Boussemaere, S. Wagner, K. Kopka, and C. Denef {beta}1-Adrenoceptors in Rat Anterior Pituitary May Be Constitutively Active. Inverse Agonism of CGP 20712A on Basal 3',5'-Cyclic Adenosine 5'-Monophosphate Levels Endocrinology, May 1, 2008; 149(5): 2391 - 2402. [Abstract] [Full Text] [PDF]