CONICET | Buscador de Institutos y Recursos Humanos

Ghrelin is a stomach-derived hormone that acts in the brain to regulate food intake, stress, and glucose homeostasis. Small doses of peripherally administrated ghrelin mainly activate neurons in the hypothalamic arcuate nucleus; however, higher doses also activate neurons in dorsal periventricular hypothalamic sites suggesting the passage of ghrelin from the periphery to the cerebrospinal fluid (CSF). Tanycytes are highly specialized ependymal cells that form a blood?cerebrospinal fluid barrier at the level of the median eminence/arcuate nucleus. Recently, it has been proposed that tanycytes could transport hormones from the blood to the CSF. Here, we hypothesize that tanycytes are able to perform ghrelin uptake from either the periphery and/or the CSF. In order to test this possibility, we centrally injected mice and rats with fluorescent ghrelin and mapped its localization in the ependymal and periventricular hypothalamic areas. In addition, we developed an in vitro model of primary cultures enriched in tanycytes. We found that hypothalamic tanycytes are able to incorporate ghrelin injected centrally from the third ventricle to the hypothalamic parenchyma. In the in vitro system, we detected tanycytes-like cells, which were immuno-reactive for vimentin and incorporated fluorescein ghrelin tracer added to the culture media. We conclude that hypothalamic tanycytes could be an important physiological checkpoint regulating the hypothalamic actions of ghrelin.