In turn, ascending projections from GLP-1 and NA neurons, including PrRP neurons, provide a route through which interoceptive feedback from the gastrointestinal tract and other organ systems can shape hypothalamic and limbic forebrain functions (Sawchenko, 1983; Loewy, 1990; Onaka et al., 1995, 2010; Blessing, 1997; Rinaman and Schwartz, 2004).