title: Direct actions of adrenergic agents on rat anterior pituitary cells.
abstract: We studied the effects of adrenergic agents on the five main cell types of the rat anterior pituitary by monitoring the changes of the cytosolic free [Ca2+] ([Ca2+]i) in single cells that were identified by multiple sequential primary immunocytochemistry at the end of the Ca2+ measurements. Adrenaline (100 nM) increased [Ca2+]i in 30% of the cells. Responses were most prominent in somatotrophs and corticotrophs (40-65% of the cells responded) whereas the other three cell types, lactotrophs, thyrotrophs and gonadotrophs, gave poorer responses. Selective agonists and antagonists revealed the presence of both alpha1- and beta-adrenergic receptors. Alpha1-receptors dominated in corticotrophs, beta-receptors in somatotrophs. The alpha1-adrenergic responses increased with culture of the cells. The beta-adrenergic responses were mediated by cAMP and consisted of stimulation of Ca2+ entry through L-type voltage-gated channels. Stimulation of alpha1-receptors released Ca2+ from intracellular stores in corticotrophs and induced cAMP-independent Ca2+ entry in somatotrophs. The effects of alpha1-agonists were additive with those of the releasing factors growth hormone-releasing hormone (GHRH) and corticotropin releasing factor (CRF) whereas those of the beta-agonists were not. Our results suggest that direct effects of plasma catecholamines on AP cells may contribute to the hormonal response to stress.
authors.affiliation: Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Departamento de Fisiología y Bioquímica, Facultad de Medicina, Valladolid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Alarcón
authors.forename: L
authors.initials: L
authors.lastname: Núñez
authors.forename: J
authors.initials: J
authors.lastname: García-Sancho
mesh_terms: D018663:Adrenergic Agents / Q000494:pharmacology*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003000:Clonidine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D003470:Culture Media; D004837:Epinephrine / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011224:Prazosin / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D013972:Thyrotropin / Q000378:metabolism
chemical_list: D018663:Adrenergic Agents; D003470:Culture Media; D005576:Colforsin; D010656:Phenylephrine; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone; D003346:Corticotropin-Releasing Hormone; D013007:Growth Hormone-Releasing Hormone; D011433:Propranolol; D007545:Isoproterenol; D003000:Clonidine; D002118:Calcium; D011224:Prazosin; D004837:Epinephrine