Title: beta 1-adrenoceptor expression in rat anterior pituitary gonadotrophs and in mouse alpha T3-1 and L beta T2 gonadotrophic cell lines
Authors: Janssens, Kristel
Krylyshkina, Olga
Hersmus, Nicole
Vankelecom, Hugo
Denef, Carl # ×
Issue Date: May-2008
Publisher: Endocrine soc
Series Title: Endocrinology vol:149 issue:5 pages:2313-24
Abstract: The rat anterior pituitary expresses beta(2)-adrenoceptors (ARs) on somatotrophs, lactotrophs, and corticotrophs. The present study investigates whether beta(1)-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 beta(1)-AR mRNA and protein. Unlike the beta(2)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 beta(1)-ARmRNAlevels. As examined by immunofluorescence confocal microscopy, beta(1)-AR immunoreactivity was detected in a subpopulation of gonadotrophs, but not in somatotrophs, lactotrophs, corticotrophs, thyrotrophs, or folliculo-stellate cells. beta(1)-AR-immunoreactivity cells were often surrounded by cup-shaped lactotrophs. Consistent with these findings, beta(1)-AR mRNA was considerably more abundant in the gonadotrophic alpha T3-1 and L beta T2 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 beta(1)-AR mRNA levels in aggregates from a subpopulation enriched in large gonadotrophs obtained by gradient sedimentation. In contrast, excessive DEX-dependent up-regulation of beta(1)-AR mRNA was found in a subpopulation enriched in small nonhormonal cells. The present data indicate that beta(1)-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.
ISSN: 0013-7227
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Tissue Plasticity (-)
Pharmacology Section (-)
× corresponding author
# (joint) last author

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