S-106
Glucocorticoids modulate endocytic activity of hypothalamic tanycytes in vitro
Ivana María Gomez1, Daniel Castrogiovanni1, María José Tolosa1, María Guillermina Zubiría2, Andrés Giovambattitsa2, Mario Perelló1,3, Pablo Nicolás De Francesco1
  1. Neurophysiology Laboratory - Multidisciplinary Institute of Cell Biology (IMBICE), La Plata, Argentina.
  2. Metabolism and Adipose Tissue Laboratory - Multidisciplinary Institute of Cell Biology (IMBICE), La Plata, Argentina.
  3. Department of Surgical Sciences, Functional Pharmacology and Neuroscience, University of Uppsala, Uppsala, Sweden.
Presenting Author:
Ivana María Gomez
ivanamariagomez@gmail.com
Hypothalamic tanycytes are polarized ependymoglial cells that line the base of the third ventricle and extend their processes into the hypothalamic parenchyma and the median eminence, establishing contacts with blood vessels and thus forming an anatomical interface for the transport of molecules between the blood and the cerebrospinal fluid. This interface may undergo structural and functional remodeling in response to the endocrine state, potentially altering its capacity for hormone transport. We recently demonstrated that tanycytes internalize and transport the orexigenic hormone ghrelin via clathrin-mediated endocytosis. Here, we analyzed the effects of glucocorticoids on tanycyte endocytic activity in vitro. Primary cultures of rat hypothalamic tanycytes were treated for 48 h with either vehicle, 0.1 μM dexamethasone (Dex), or 0.1 μM corticosterone (Cort), in the presence or absence of the glucocorticoid receptor (GR) antagonist RU-486 or the mineralocorticoid receptor (MR) antagonist spironolactone. Immunocytochemistry revealed GR and MR expression in the cytoplasm and only Dex induced GR nuclear translocation. Both Dex and Cort increased uptake of fluorescent ghrelin and fluospheres, an effect reversed by RU-486 and spironolactone. We conclude that glucocorticoids enhance tanycyte endocytic capacity in vitro, likely via GR activation. Future studies will address the cellular mechanisms involved and the impact of glucocorticoids on tanycyte-mediated transport in vivo.