The expression of estrogen receptor alpha isoform on the adenohypophyseal cell surface is regulated by 17beta-estradiol

GUTIÉRREZ S.; SOSA L.; PETITI, J. P.; MUKDSI J. H.; DE PAUL A.L.; TORRES A.I.

Huerta Grande, Córdoba, Argentina

Congreso; II Reunión Conjunta de Neurociencias; 2010

17beta-estradiol (E2) activates membrane estrogen receptors (ER), but its identity remains controversial. We sought to identify ER in plasma membrane of pituitary cells and to establish if E2 modifies this subcellular localization. Pituitary cell cultures from female rats were treated with 10nM of E2 and ERalpha and beta agonists (PPT, DPN) for 0, 5, 15 and 30min and with the inhibitors ICI182780, PD98059 and Gö6976. ERalpha and beta were detected by confocal microscopy (CM, using Concanavalin A as a membrane marker), flow cytometry (FC) and electron microscopy (EM). Also, PKCalpha and ERK1/2 were evaluated by western blot (WB). Statistical analysis: ANOVA-Fisher. By CM, ERalpha and beta were detected in the nucleus and cytosol of control cells, E2 or PPT for 5min increased ERalpha in plasma membrane, co-localizing with Concavanalina A. Only ERalpha was detected on cell surface with EM. By CF in all experimental conditions, 8% of lactotrophs expressed ERalpha on the surface, but after 5min of stimulation a 20% of these positive-ERalpha cells showed a higher intensity of immunostaining. By MC and WB, PKC and ERK1/2 activation was observed. These effects were reversed by the inhibitors. These results evidence the presence of functional ERalpha in the plasma membrane of pituitary cells and suggest that E2 increased its expression.