Does L-DOPA have neuroendocrine effects?

MORA OGANDO; SANDRA ZARATE; MARIA LAURA MAGRI; MARIA FLORENCIA GOTTARDO; GABRIELA JAITA; GUADALUPE EIJO; ADRIANA SEILICOVICH; JIMENA FERRARIS; DANIEL PISERA

Huerta Grande, Córdoba

Congreso; XXIX Congreso de la Sociedad Argentina de Neurociencias; 2014

Sociedad Argentina de Investigación en Neurociencias

L-3,4-dihydroxyphenilalanine (L-DOPA) is a precursor in dopamine (DA) biosynthesis, and it is released by hypothalamic neurons. In the anterior pituitary (AP), DA is the main regulator of lactotrope function, and its actions are modulated by estrogens (E2). Although L-DOPA is the main drug for Parkinson?s desease treatment, there are not systematic studies about its neuroendrocrine effects. Our hypothesis is that L-DOPA has direct effects on AP function, including the modulation of its tissue homeostasis. Administration of L-DOPA (50mg/kg, ip, 6h) to ovarectomized female (OVX) rats increased the percentage of hypodiploid cells in the AP, while it did not affect cell cycle progression. In vitro, L-DOPA decreased the percentage of apoptotic anterior pituitary cells, only in the absence of E2. In GH3 cells, L-DOPA had an antiapoptotic effect in the absence of E2. Dopa- decarboxylase (AADC) converts L-DOPA to DA. We investigated its pituitary expression by immunofluorescence. The three lobes of pituitary gland express AADC. In AP, we observed expression of this enzyme in lactotropes and other cell types. In conclusion, L-DOPA modifies the apoptotic rate of AP cells. These actions are modulated by E2. The fact that AADC is expressed in pituitary gland suggests that there may be local synthesis of DA from L-DOPA, as it occurs in other tissues. In parkinsonian patients, L-DOPA treatment may produce neuroendocrine effects that need to be understood in more detail.