Anterior pituitary gland synthesises dopamine from l ‐3,4‐dihydroxyphenylalanine ( l ‐dopa)

ORRILLO, SANTIAGO JORDI; DE DIOS, NATALY; ASAD, ANTONELA SOFÍA; DE FINO, FERNANDA; IMSEN, MERCEDES; ROMERO, ANA CLARA; ZÁRATE, SANDRA; FERRARIS, JIMENA; PISERA, DANIEL

JOURNAL OF NEUROENDOCRINOLOGY.

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 32

0953-8194

Prolactin (PRL) is a hormone principally secreted by lactotrophs of the anterior pituitarygland. Although the synthesis and exocytosis of this hormone are mainly under theregulation of hypothalamic dopamine (DA), the possibility that the anterior pituitarysynthesizes this catecholamine remains unclear. In this study, our aim was to determineif the anterior pituitary produces DA from the precursor L-Dopa. To this purpose, westudied the expression of aromatic L-amino acid decarboxylase (AADC) enzyme andthe transporter VMAT2 in the anterior pituitary, AtT20 and GH3 cells byimmunofluorescence and western blot. Moreover, we investigated the production of DAAccepted ArticleThis article is protected by copyright. All rights reservedfrom L-Dopa and its release in vitro. Then, we explored the effects of L-Dopa in thesecretion of PRL from anterior pituitary fragments. We observed that the anteriorpituitary, AtT20 and GH3 cells express both AADC and VMAT2. Next, we detected anincrease in DA content after anterior pituitary fragments were incubated with L-Dopa.Also, the presence of L-Dopa increased DA levels in incubation media and reducedPRL secretion. Likewise, the content of cellular DA increased after AtT20 cells wereincubated with L-Dopa. In addition, L-Dopa reduced CRH-stimulated ACTH releasefrom these cells after AADC activity was inhibited by NSD-1015. Moreover, DAformation from L-Dopa increased apoptosis and decreased proliferation. However, inthe presence of NSD-1015, L-Dopa decreased apoptosis and increased proliferationrates. These results suggest that the anterior pituitary synthesizes DA from L-Dopa byAADC and this catecholamine can be released from this gland contributing to thecontrol of PRL secretion. In addition, our results suggest that L-Dopa exerts directactions independently from its metabolization to DA.