RRC ID 43237
Author Janssens K, Krylyshkina O, Hersmus N, Vankelecom H, Denef C.
Title Beta1-adrenoceptor expression in rat anterior pituitary gonadotrophs and in mouse alphaT3-1 and LbetaT2 gonadotrophic cell lines.
Journal Endocrinology
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)-AR mRNA levels. 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 alphaT3-1 and LbetaT2 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.
Volume 149(5)
Pages 2313-24
Published 2008-5-1
DOI 10.1210/en.2007-1396
PII en.2007-1396
PMID 18202120
MeSH Adrenergic beta-1 Receptor Agonists Adrenergic beta-2 Receptor Agonists Animals Cell Line Dexamethasone / pharmacology Gene Expression Regulation / drug effects Glucocorticoids / pharmacology Glycoprotein Hormones, alpha Subunit / metabolism Gonadotrophs / drug effects Gonadotrophs / metabolism* Isoproterenol / pharmacology Luteinizing Hormone, beta Subunit / metabolism Male Mice Pituitary Gland, Anterior / drug effects Pituitary Gland, Anterior / metabolism Pituitary Gland, Intermediate / drug effects Pituitary Gland, Intermediate / metabolism RNA, Messenger / metabolism Rats Rats, Wistar Receptors, Adrenergic, beta-1 / genetics* Receptors, Adrenergic, beta-1 / metabolism Receptors, Adrenergic, beta-2 / genetics Receptors, Adrenergic, beta-2 / metabolism
IF 3.934
Times Cited 3
Human and Animal Cells