title: Evidence for a paracrine role of endogenous adrenomedullary galanin in the regulation of glucocorticoid secretion in the rat adrenal gland.
abstract: Previous investigations have shown that rat adrenocortical cells are provided with galanin receptors, and galanin stimulates glucocorticoid secretion from dispersed cells. The present study aimed to clarify the possible role of galanin in the physiological regulation of rat adrenal secretory activity. Reverse transcription-polymerase chain reaction detected galanin mRNA expression in the adrenal medulla, but not in the cortex. Sizeable concentrations of galanin-immunoreactivity were measured by radioimmune assay only in the adrenomedullary tissue. Galanin raised norepinephrine, but not epinephrine, release from adrenomedullary tissue. Galanin immunoneutralization (obtained with concentrations of anti-galanin antibody able to block the galanin glucocorticoid secretagogue effect on dispersed adrenocortical cells) decreased basal corticosterone production from adrenal slices containing adrenomedullary tissue, without affecting that from dispersed adrenocortical cells. The beta-adrenoceptor antagonist l-alprenolol partially prevented galanin-stimulated corticosterone secretion from adrenal slices, without per se altering basal secretion. Taken together, our findings allow us to conclude that endogenous galanin, produced in adrenal medulla, is involved in the regulation of adrenocortical glucocorticoid secretion acting via a two-fold paracrine mechanism: i) direct activation of adrenocortical galanin receptors; and ii) stimulation of adrenomedullary release of catecholamines, which in turn activate beta-adrenoceptors located on adrenocortical cells.
authors.affiliation: Department of Human Anatomy and Physiology, Section of Anatomy, University of Padua, I-35121 Padua, Italy.
authors.forename: Paola G
authors.initials: PG
authors.lastname: Andreis
authors.forename: Cinzia
authors.initials: C
authors.lastname: Tortorella
authors.forename: Agnieska
authors.initials: A
authors.lastname: Ziolkowska
authors.forename: Raffaella
authors.initials: R
authors.lastname: Spinazzi
authors.forename: Ludwik K
authors.initials: LK
authors.lastname: Malendowicz
authors.forename: Giuliano
authors.initials: G
authors.lastname: Neri
authors.forename: Gastone G
authors.initials: GG
authors.lastname: Nussdorfer
mesh_terms: D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism*; D000526:Alprenolol / Q000494:pharmacology; D000818:Animals; D002395:Catecholamines / Q000378:metabolism; D003345:Corticosterone / Q000378:metabolism*; D019004:Galanin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D009500:Neutralization Tests; D019899:Paracrine Communication / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002395:Catecholamines; D012333:RNA, Messenger; D000526:Alprenolol; D019004:Galanin; D003345:Corticosterone