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Vagal innervation of the aldosterone-sensitive HSD2 neurons in the NTS
Journal article   Peer reviewed

Vagal innervation of the aldosterone-sensitive HSD2 neurons in the NTS

Jung-Won Shin, Joel C Geerling and Arthur D Loewy
Brain research, Vol.1249, pp.135-147
01/16/2009
DOI: 10.1016/j.brainres.2008.10.058
PMCID: PMC2666048
PMID: 19010311
url
http://doi.org/10.1016/j.brainres.2008.10.058View
Open Access

Abstract

The nucleus of the solitary tract (NTS) contains a unique subpopulation of aldosterone-sensitive neurons. These neurons express the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (HSD2) and are activated by sodium deprivation. They are located in the caudal NTS, a region which is densely innervated by the vagus nerve, suggesting that they could receive direct viscerosensory input from the periphery. To test this possibility, we injected the highly sensitive axonal tracer biotinylated dextran amine (BDA) into the left nodose ganglion in rats. Using confocal microscopy, we observed a sparse input from the vagus to most HSD2 neurons. Roughly 80% of the ipsilateral HSD2 neurons exhibited at least one close contact with a BDA-labeled vagal bouton, although most of these cells received only a few total contacts. Most of these contacts were axo-dendritic (approximately 80%), while approximately 20% were axo-somatic. In contrast, the synaptic vesicular transporters VGLUT2 or GAD7 labeled much larger populations of boutons contacting HSD2-labeled dendrites and somata, suggesting that direct input from the vagus may only account for a minority of the information integrated by these neurons. In summary, the aldosterone-sensitive HSD2 neurons in the NTS appear to receive a small amount of direct viscerosensory input from the vagus nerve. The peripheral sites of origin and functional significance of this projection remain unknown. Combined with previously-identified central sources of input to these cells, the present finding indicates that the HSD2 neurons integrate humoral information with input from a variety of neural afferents.
 Immunohistochemistry Synapses - physiology Rats Male Rats, Sprague-Dawley Microscopy, Confocal Aldosterone - metabolism Neural Pathways - anatomy & histology Animals Solitary Nucleus - anatomy & histology Neurons - enzymology 11-beta-Hydroxysteroid Dehydrogenase Type 2 - metabolism Neurons - physiology Vagus Nerve - anatomy & histology

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