The nucleus tractus solitari (NTS) participates in peripheral ghrelin glucostatic hunger signalling mediated by insulin

Three extrahypothalamic areas, the nucleus of the tractus solitari (NTS), the central nucleus of the amygdala (CeA) and the dorsal raphe nucleus (DRN), all potentially involved in peripheral ghrelin signalling of appetite control mediated by the glucose levels were examined. Thus, a specific anti-ghrelin antibody (AGA) was intravenously administered in order to remove the ghrelin signalling and then, subsequently, 4-h food intake, plasma glucose levels and the brain c-fos expression in the NTS, CeA and DRN were assessed. Food intake significantly decreased when the AGA was administered. NTS c-Fos expression was significantly augmented by insulin, while it was significantly decreased by the AGA. These results suggest that the NTS is a part of the ghrelin pathway that regulates the orexigenic signalling cascade, which may be triggered by a drop in blood glucose levels mediated by insulin.