title: Effects of glucocorticosteroids on prolactin and growth hormone production and characterization of the intracellular hormone receptors in rat pituitary tumour cells.
abstract: The effect of corticosterone and dexamethasone on the production of growth hormone and prolactin was studied in rat pituitary tumour cells (GH3-cells) in culture. Corticosterone and dexamethasone caused a dose-dependent stimulation of growth hormone synthesis, and the highest concentration (10(-6) mol/l) increased growth hormone levels to 250% of controls. This concentration, however, decreased prolactin synthesis to 25% of the control values. The cytosol fractions from monolayer cultures as well as from tumours of GH3-cells were found to possess receptor molecules for glucocorticoid hormones, having a sedimentation constant close to 8 S in a salt-free buffer and 4 S in the presence of 0.5 mol/l KCL. Isoelectric point of the receptor was 5.8. Scatchard analysis showed one single class of binding sites with high affinity (Kd 2.1 +/- 0.4 (SD X 10(-9) mol/l). Studies on the steroid specificity revealed that dexamethasone had the highest affinity for the receptor. Corticosterone, cortisol and progesterone had also high affinity, whereas testosterone and oestradiol-17 beta had no significant affinity for the receptors. After in vivo administration of [3H]dexamethasone to GH3 tumour-bearing rats, radioactivity could be extracted from purified nuclei bound to 4 S macromolecules. The presence of receptors for glucocorticosteroid hormones in the GH3-cells, suggests that these hormones may alter growth hormone and prolactin production at the anterior pituitary level.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003345:Corticosterone / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000096:biosynthesis*; D008297:Male; D009374:Neoplasms, Experimental / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011388:Prolactin / Q000096:biosynthesis*; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D003907:Dexamethasone; D011388:Prolactin; D013006:Growth Hormone; D003345:Corticosterone