Many YFP-immunoreactive axons (green) closely apposed the TH-positive neurons (red) of the NTS.

<p>Fluorescent YFP– preproglucagon neurons (green) and DAPI (nuclear stain, blue) in coronal sections through the NTS of YFP–PPG mice. Micrographs showing the caudal NTS (A-B), the NTS at the level of the area postrema (C-D) and the NTS at the level of the 4^th ventricle (E-F). Cell bodies of YFP-immunoreactive preproglucagon neurons (green) were detected at the level of the area postrema and just caudally to the area postrema (A-D). Many green YFP-immunoreactive axons closely appose blue DAPI-labeled cell bodies in the NTS. White arrows indicate NTS TH-positive neuronal cell bodies closely apposed by the GLP-1 fibers. Insets in panels B,D and F show the interaction at a single neuron level. Area postrema (AP), central canal (cc), dorsal motor nucleus of the vagus (DMV), gracile nucleus (Gr), 4^th ventricle (4thV). B,D and F show higher magnification of areas in A,C and D, respectively.