Neuroendocrinology and Neuroimmunology
Author: Ivana María Gomez | email: igomez@imbice.gov.ar
Ivana María Gómez 1°, Daniel Castrogiovanni 1°, Maia Uriarte 1°, Mario Perelló 1°, Pablo Nicolás De Francesco 1°
1° Laboratorio de Neurofisiología- Instituto Multidisciplinario de Biología Celular (IMBICE, CIC-CONICET-UNLP)
Hypothalamic tanycytes are polarized glial cells that line the base of the third ventricle. Their somas contact the cerebrospinal fluid (CSF), while their terminal side (endfeet) contact the capillaries of the blood-brain barrier (BBB) or the fenestrated capillaries of the median eminence, forming a relevant anatomical interface for the transport of molecules between blood and CSF. We recently described that tanycytes are involved in the transport of the orexigenic hormone ghrelin. Here, we study the cellular mechanisms of ghrelin uptake by hypothalamic tanycytes and its transport direction. Specifically, we incubated primary cultures of rat hypothalamic tanycytes with a fluorescent variant of ghrelin (Fr-ghrelin) in basal conditions or after pharmacological blockage of either clathrin-mediated internalization using Pitstop, or intracellular transport using colchicine. We then quantified fluorescence intensity in soma, process and endfeet of each cell. We found that intracellular fluorescence: 1) is found predominantly in the soma of tanycytes after a 5 min incubation; 2) increased in somas, processes and terminals after 30 min incubation, as compared to 5 min incubation; 3) was reduced only in terminals in the presence of colchicine; and 4) decreased in all compartments in the presence of Pitstop. This evidence shows that tanycytes are able to internalize ghrelin through clathrin-mediated endocytosis and presumably to transport it from the apical side to the terminal side.