Cholinergic neurons in the mouse rostral ventrolateral medulla target sensory afferent areas

Ruth L. Stornetta, Conrad J. Macon, Thanh M. Nguyen, Melissa B. Coates, Patrice G. Guyenet

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The rostral ventrolateral medulla (RVLM) primarily regulates respiration and the autonomic nervous system. Its medial portion (mRVLM) contains many choline acetyltransferase (ChAT)-immunoreactive (ir) neurons of unknown function. We sought to clarify the role of these cholinergic cells by tracing their axonal projections. We first established that these neurons are neither parasympathetic preganglionic neurons nor motor neurons because they did not accumulate intraperitoneally administered Fluorogold. We traced their axonal projections by injecting a Cre-dependent vector (floxed-AAV2) expressing either GFP or mCherrry into the mRVLM of ChAT-Cre mice. Transduced neurons expressing GFP or mCherry were confined to the injection site and were exclusively ChAT-ir. Their axonal projections included the dorsal column nuclei, medullary trigeminal complex, cochlear nuclei, superior olivary complex and spinal cord lamina III. For control experiments, the floxed-AAV2 (mCherry) was injected into the RVLM of dopamine beta-hydroxylase-Cre mice. In these mice, mCherry was exclusively expressed by RVLM catecholaminergic neurons. Consistent with data from rats, these catecholaminergic neurons targeted brain regions involved in autonomic and endocrine regulation. These regions were almost totally different from those innervated by the intermingled mRVLM-ChAT neurons. This study emphasizes the advantages of using Cre-driver mouse strains in combination with floxed-AAV2 to trace the axonal projections of chemically defined neuronal groups. Using this technique, we revealed previously unknown projections of mRVLM-ChAT neurons and showed that despite their close proximity to the cardiorespiratory region of the RVLM, these cholinergic neurons regulate sensory afferent information selectively and presumably have little to do with respiration or circulatory control.

Original languageEnglish (US)
Pages (from-to)455-475
Number of pages21
JournalBrain Structure and Function
Volume218
Issue number2
DOIs
StatePublished - Mar 2013
Externally publishedYes

Keywords

  • Acetylcholine
  • Medulla oblongata
  • Somatosensory processing

ASJC Scopus subject areas

  • Anatomy
  • Neuroscience(all)
  • Histology

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