Neurons with diverse phenotypes project from the caudal to the rostral nucleus of the solitary tract

Abstract

The nucleus of the solitary tract is a potential site for taste-visceral interactions. Connections from the caudal, visceral area of the nucleus (cNST) to the rostral, gustatory zone (rNST) have been described, but the phenotype of cells giving rise to the projection(s) and their distribution among rNST subdivisions are unknown. To determine these characteristics of the intrasolitary pathway, we injected pan-neuronal and floxed AAV viruses into the cNST of mice expressing cre in glutamatergic, GABAergic or catecholaminergic neurons. Particular attention was paid to the terminal field distribution in rNST subdivisions by simultaneously visualizing P2×2 localized to gustatory afferent terminals. All three phenotypically-identified pathways terminated in rNST, with the density greatest for glutamatergic and sparsest for catecholaminergic projections, observations supported by retrograde tracing. Interestingly, cNST neurons had more prominent projections to rNST regions medial and ventral to P2×2 staining, i.e., the medial and ventral subdivisions. In addition, GABAergic neurons projected robustly to the lateral subdivision and adjacent parts of the reticular formation and spinal trigeminal nucleus. Although cNST neurons also projected to the P2×2-rich central subdivision, such projections were sparser. These findings suggest that cNST visceral signals exert stronger excitatory and inhibitory influences on local autonomic and reflex pathways associated with the medial and ventral subdivisions compared to weaker modulation of ascending pathways arising from the central subdivision and ultimately destined for the forebrain.

Exploring the Mechanism on the Medullary Visceral Zone Inhibiting the Cholinergic Anti-inflammatory Pathway Induced by Sepsis

“…Therefore, it is very attractive question deserve to explore. MVZ consists of various types of neurons such as cholinergic neurons, catecholaminergic neurons, peptide energetic neurons, glutamate energetic neurons, and gamma-aminobutyric acid (GABA) energetic neurons, which are all involved in autonomic regulation, especially cholinergic neurons, catecholaminergic neurons [ 45 ]. In our study, immunofluorescence images showed that cholinergic neurons were mainly concentrated in the NST, DVMN, and Ventrolateral Reticular Nucleus (VLRN); catecholaminergic neurons were mainly distributed in NST, DVMN, VLRN, and the Area Postrema (AP).…”

Primary sensory map formations reflect unique needs and molecular cues specific to each sensory system

“…Crafting of tongues to foreign areas such as orbit and liver has long established the independence of taste bud development 171, 172 . More experimental data are needed on the molecular guidance of taste afferents, the functional significance of orotopic organization, inter-solitary nucleus connections 25, 173 , and higher-order interactions 174 . Importantly, no data exist showing how the orotopic projection develops in the absence of taste buds 165 and where afferents end long term in the absence of a central target 170 .…”

Taste Responses in the Nucleus of the Solitary Tract of Awake Obese Rats Are Blunted Compared With Those in Lean Rats

“…NTS neurons express a wide array of receptors involved in the homeostatic regulation of ingestion (Ritter et al, 2000; Faulconbridge et al, 2003; Rozengurt, 2006; Cui et al, 2011; Blouet and Schwartz, 2012; Zhan et al, 2013). Moreover, there is a large degree of intranuclear connectivity bridging the caudal viscerosensory pole with the rostral orosensory pole (Beckman and Whitehead, 1991; Ganchrow et al, 2014; Travers et al, 2018). With reciprocal connectivity from forebrain structures controlling feeding behavior such as the amygdala and hypothalamus (Whitehead et al, 2000) along with parallels in the vagal-visceral and lingual pathways (Karimnamazi et al, 2002), the gustatory system is a highly interactive and integrative system, with the NTS being a crucial first node in the feeding circuit.…”