Neuroanatomical and functional characterization of ghrelin receptor-expressing neurons of the nucleus of the solitary tract in a transgenic mouse model

KOÇ V; CORNEJO MP; GARCÍA ROMERO G; REYNALDO M; DE FRANCESCO PN; PADÍN ME; PERELLÓ M

Buenos Aires

Congreso; 2nd Congress of the Federation of Latin-American and Caribbean Societies for Neuroscience (FALAN); 2016

Federation of Latin-American and Caribbean Societies for Neuroscience

The nucleus of the solitary tract (NST) is a sensory nucleus in the dorsal medulla that receives visceral, gustatory, and orotactile information, amongst others. It is part of the dorsal vagal complex, which regulates food intake and relays autonomic reflexes controlling glucaemia, blood pressure and gastro-intestinal motility. Some NST neurons express the growth hormone secretagogue receptor (GHSR), the target of the hormone ghrelin. Here, we used a transgenic mouse line in which green fluorescent protein (GFP) is under the control of the GHSR promoter (GHSR-GFP mice) to perform a detailed neuroanatomical description and a functional exploration of the GHSR-expressing neurons of the NST. GFP+ neurons were distributed throughout the NST, but preferentially formed two clusters within its rostral and caudal ends. These neurons were negative for M-enk, TH, NPY, TRH, ChAT and GAD-67, as shown by immunophenotypic analysis. We explored the activation of these neurons by exposing GHSR-GFP mice to experimental paradigms known to activate the NST (48h fasting, gastric distention, 24h water deprivation, i.p. LiCl administration, i.p. hypertonic NaCl administration, oral sucrose administration, and high-fat diet binge eating), and mapping the induction of c-Fos. We found that only high-fat diet binge eating group showed a significant increase of c-Fos expression in NST GFP+ neurons. Thus, we conclude that GHSR-expressing neurons of the NTS are activated by acute intake of high fat diet.