Most neurons in the nucleus tractus solitarii do not send collateral projections to multiple autonomic targets in the rat brain

Sam M. Hermes, Jennifer L. Mitchell, Sue Aicher

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The nucleus tractus solitarii (NTS) receives primary visceral afferents and sends projections to other autonomic nuclei at all levels of the neuroaxis. However, it is unknown if distinct populations of NTS neurons project to individual autonomic targets or if individual neurons in the NTS project to multiple autonomic targets. Understanding the basic circuitry of visceral reflex pathways is essential for the analyses of functional central autonomic networks. We examined projections from the NTS to autonomic targets within the hypothalamus (paraventricular nucleus, PVN), pons (parabrachial nucleus, PB), and medulla (caudal ventrolateral medulla, CVL) using retrograde tracing and immunohistochemistry. Dual retrograde tracer microinjections were made into pairs of targets (PVN + CVL; PVN + PB; PB + CVL), and the pattern of retrograde labeling was examined within NTS. The extent of collateralization, seen as dual retrogradely labeled neurons, was negligible for combined PVN and CVL injections and increased for injections combining PB with either PVN or CVL, but the majority of NTS neurons project to only one autonomic target. Immunohistochemistry for tyrosine hydroxylase (TH) was used to examine the pattern of TH-immunoreactivity (TH-ir) within retrogradely labeled NTS neurons. TH-ir was seen predominantly in projections to PVN, to a lesser degree in projections to PB, and was largely absent from projections to CVL. The percentage of dual retrogradely labeled neurons displaying TH-ir corresponded to the target displaying the most TH-ir, and TH-ir was not predictive of collateralization. Together, these results indicate that NTS neurons project to individual autonomic targets in the brain.

Original languageEnglish (US)
Pages (from-to)539-551
Number of pages13
JournalExperimental Neurology
Volume198
Issue number2
DOIs
StatePublished - Apr 2006

Fingerprint

Solitary Nucleus
Paraventricular Hypothalamic Nucleus
Tyrosine 3-Monooxygenase
Neurons
Brain
Immunohistochemistry
Visceral Afferents
Injections
Pons
Microinjections
Hypothalamus
Reflex

Keywords

  • Caudal ventrolateral medulla
  • Hypothalamus
  • Parabrachial
  • Paraventricular

ASJC Scopus subject areas

  • Neurology
  • Neuroscience(all)

Cite this

Most neurons in the nucleus tractus solitarii do not send collateral projections to multiple autonomic targets in the rat brain. / Hermes, Sam M.; Mitchell, Jennifer L.; Aicher, Sue.

In: Experimental Neurology, Vol. 198, No. 2, 04.2006, p. 539-551.

Research output: Contribution to journalArticle

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