Ghrelin uptake by the blood-cerebrospinal fluid barrier occurs in a ghrelin receptor-independent manner

MAIA URIARTE; GIMENA FERNANDEZ; NICOLAS DE FRANCESCO; DANIELA LUFRANO; AGUSTINA CABRAL; MARIO PERELLO

Congreso; XXX Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2015

Ghrelin is a 28-amino acid octanoylated peptide hormone secreted from the stomach. It has been suggested that one of the mechanisms by which ghrelin reaches the brain involves crossing the blood-cerebrospinal fluid barrier at either the choroids plexus and/or the hypothalamic tanycytes that line the floor of the third ventricle. However, the mechanisms mediating the transport of ghrelin into the brain are currently unknown. The goal of this study was to get insights into the system mediating ghrelin uptake at the bloodcerebrospinal fluid barrier. We found that both the ependymal cells of the choroids plexus and the hypothalamic tanycytes display fluorescent-ghrelin tracer uptake in vivo. Interestingly, we failed to find ghrelin receptor gene expression within these cell types or an increase of pERK levels, a downstream target of ghrelin receptor signaling, by ghrelin or the fluorescent-ghrelin tracer. In addition, we found that ependymal cells of the choroids plexus and the hypothalamic tanycytes of a ghrelin receptor deficient mice show similar patterns of tracer uptake as seem in wild type mice. Thus, we conclude that ghrelin uptake in the blood-cerebro spinal barrier occurs in a ghrelin receptor-independent fashion.