Mapping of Sensory Nerve Subsets within the Vagal Ganglia and the Brainstem Using Reporter Mice for Pirt, TRPV1, 5-HT3, and Tac1 Expression

Vagal afferent sensory nerves, originating in jugular and nodose ganglia, are composed of functionally distinct subsets whose activation evokes distinct thoracic and abdominal reflex responses. We used Cre-expressing mouse strains to identify specific vagal afferent populations and map their central...

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Bibliographic Details
Published in:eNeuro 2020-03, Vol.7 (2), p.ENEURO.0494-19.2020
Main Authors: Kim, Seol-Hee, Hadley, Stephen H, Maddison, Mikayla, Patil, Mayur, Cha, Byeong, Kollarik, Marian, Taylor-Clark, Thomas E
Format: Article
Language:English
Subjects:
Afferent Pathways - metabolism
Animals
Brain Stem - metabolism
Carrier Proteins
Membrane Proteins
Mice
New Research
Nodose Ganglion - metabolism
Solitary Nucleus
TRPV Cation Channels - genetics
TRPV Cation Channels - metabolism
Vagus Nerve - metabolism
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Summary:Vagal afferent sensory nerves, originating in jugular and nodose ganglia, are composed of functionally distinct subsets whose activation evokes distinct thoracic and abdominal reflex responses. We used Cre-expressing mouse strains to identify specific vagal afferent populations and map their central projections within the brainstem. We show that Pirt is expressed in virtually all vagal afferents; whereas, 5-HT3 is expressed only in nodose neurons, with little expression in jugular neurons. Transient receptor potential vanilloid 1 (TRPV1), the capsaicin receptor, is expressed in a subset of small nodose and jugular neurons. Tac1, the gene for tachykinins, is expressed predominantly in jugular neurons, some of which also express TRPV1. Vagal fibers project centrally to the nucleus tractus solitarius (nTS), paratrigeminal complex, area postrema, and to a limited extent the dorsal motor nucleus of the vagus. nTS subnuclei preferentially receive projections by specific afferent subsets, with TRPV1 fibers terminating in medial and dorsal regions predominantly caudal of obex, whereas TRPV1 fibers terminate in ventral and lateral regions throughout the rostral-caudal aspect of the medulla. Many vagal Tac1 afferents (mostly derived from the jugular ganglion) terminate in the nTS. The paratrigeminal complex was the target of multiple vagal afferent subsets. Importantly, lung-specific TRPV1 and Tac1 afferent terminations were restricted to the caudal medial nTS, with no innervation of other medulla regions. In summary, this study identifies the specific medulla regions innervated by vagal afferent subsets. The distinct terminations provide a neuroanatomic substrate for the diverse range of reflexes initiated by vagal afferent activation.
ISSN:2373-2822
2373-2822
DOI:10.1523/eneuro.0494-19.2020