Figure 11.

These images compare axonal labeling in the dorsomedial medulla at the level of the area postrema with markers for established subpopulations of neurons in the NTS and dorsal vagal nucleus (DMX). (A) Aldosterone-sensitive NTS neurons (HSD2-ir, green) are situated along the medial border of the medial subnucleus of the NTS, amid a dense field of varicose axons from the PVH (PHAL-ir, red). This section contains the mid-caudal AP, which contained very little axonal labeling. (B) The A2 noradrenergic neurons (TH-ir, ice-blue) occupy a large extent of this dense field of PVH axon terminals. Note also the presence of dopaminergic neurons in the dorsal vagal nucleus (DMX) (arrows), with more diffuse TH immunoreactivity. Relative to the A2 neurons, these catecholaminergic vagal motoneurons receive very little input from the PVH. This section contains the caudal AP, which contains very little axonal labeling relative to the underlying NTS. C: Dense PVH projection to the rostralmost A2 noradrenergic neurons (A2r), which lie along the rostral, dorsolateral edge of the dorsal motor nucleus of the vagus (DMX). At first glance, this dense terminal field appeared to target the lateral DMX (ChAT-ir, green), but upon closer inspection in every case, this dense concentration of PVH axonal labeling appears to target the dendrites and somata of A2r neurons, while only a moderate density of terminals targets neighboring and intermingled neurons in the DMX, all of which are ChAT-ir. This section contains the rostralmost AP, which exhibits minimal axonal labeling. Panels (A) and (B) were taken from case #2223 (Figs. 2 &3 for injection site), while (C) was taken from case #2276 (injection site not shown). Scale bar = 50 μm.