Cellular localization and distribution of glucocorticoid receptor immunoreactivity and the expression of glucocorticoid receptor messenger RNA in rat pituitary gland

Abstract

By means of double immunohistochemical techniques and a nonradioisotopic in situ hybridization method, we determined the colocalization pattern of glucocorticoid receptor (GR) and pituitary hormones and the GR messenger RNA (mRNA) expression in the pituitaries of Wistar adult male rats. Immunoreactivity for GR was detected in the nuclei of cells in the anterior and posterior pituitary. Double immunohistochemistry revealed that the colocalization of GR and anterior pituitary hormones occurred in almost 99% of the growth hormone (GH)-producing cells and adrenocorticotropic hormone (ACTH)-producing cells, and in 67% of the thyroid stimulating hormone (TSH)-producing cells. Almost all of the folliculostellate cells (93%), marginal layer cells (94%) in the anterior pituitary, and pituicytes (96%) in the posterior pituitary immunostained for S100 protein antibody were also immunostained with GR. GR mRNA was abundant in the cytoplasm of anterior and intermediate pituitary cells but scattered sparsely in that of the posterior pituitary. These results suggest that glucocorticoids directly influence certain pituitary cells in order to regulate cell function, including the synthesis and/or secretion of hormones.

Functional in vitro studies on the role and regulation of interleukin-6 in human somatotroph pituitary adenomas

“…Bacterial endotoxin (LPS), IL-1, tumor necrosis factora, pituitary adenylate cyclase-activating peptide (PACAP), vasoactive intestinal peptide and calcitonin all stimulate IL-6 production via specific receptors and different signalling pathways (5,13,14). Glucocorticoid receptors expressed in FS cells (15) mediate the potent inhibitory effects of glucocorticoids on IL-6 production (8,13).…”

Expression of 3 beta-hydroxysteroid dehydrogenase/isomerase in the female rat pituitary

“…The pituitary is one of the principal target organs for steroid action: it has been demonstrated that the pituitary contains oestrogen, androgen, gluco-and mineralocorticosteroid, and retinoic acid receptors, suggesting that actions of steroids on the pituitary may be regulated by mechanisms controlling steroid receptor expression (Handa et al 1986, Kimura et al 1993, Sanno et al 1997, Shughrue et al 1998, Gittoes et al 1998, Ozawa et al 1999, Vidal et al 1999b. Little is known about the role played by steroidogenic enzymes in the regulation of pituitary cell function, including hormone synthesis and/or release.…”

“…The effect of steroids on target cells depends not only on the amounts that can penetrate into the cells, and their interaction with the receptor, but also on the formation of biologically active steroids from inactive precursors at the sites of their actions (Labrie 1991, Labrie et al 1995. Despite numerous studies that identified the presence of steroid receptors in the pituitary of different species (Handa et al 1986, Kimura et al 1993, Sanno et al 1997, Gittoes et al 1998, Shughrue et al 1998, Ozawa et al 1999, Vidal et al 1999b, only a few publications have dealt with the localization of steroidogenic enzymes in adenohypophyseal cells. The scarcity of reports may be due to methodological limitations related to the small amount of these proteins in the pituitary compared with the ovary, testis and adrenal cortex.…”

Folliculo-stellate Cells: Paracrine Communicators in the Anterior Pituitary

“…Most of the endocrine cells contain glucocorticoid receptors and so are subject to transcriptional inhibition by glucocorticoids, but lactotrophs apparently do not [73] and all are subject to the early delayed glucocorticoid-induced inhibition that requires Anx A1 as demonstrated by the blocking effects of both antibodies and antisense [92,93]. F-S cells make functional contacts with all the classical endocrine cell types in proportion to their number and the Anx A1 that they export can therefore exert the early-delayed feedback on secretion of all adenohypophyseal hormones.…”

“…IL-6 is a strong stimulant of the HPA axis and its expression is stimulated by TGF , PACAP and glucocorticoids [95,96]. At present it is Rat pituitary [73] TtT/GF cells [19] Leptin (common, ObRa and long, ObRb forms)…”