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Auton Neurosci. 2018 Mar;210:44-54. doi: 10.1016/j.autneu.2017.12.005. Epub 2017 Dec 20.

Variable expression of GFP in different populations of peripheral cholinergic neurons of ChATBAC-eGFP transgenic mice.

Author information

1
Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
2
School of Natural Sciences and Mathematics, Ferrum College, Ferrum, VA 24088, USA.
3
Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA; Center of Excellence in Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, TN 37614, USA. Electronic address: hoover@etsu.edu.

Abstract

Immunohistochemistry is used widely to identify cholinergic neurons, but this approach has some limitations. To address these problems, investigators developed transgenic mice that express enhanced green fluorescent protein (GFP) directed by the promoter for choline acetyltransferase (ChAT), the acetylcholine synthetic enzyme. Although, it was reported that these mice express GFP in all cholinergic neurons and non-neuronal cholinergic cells, we could not detect GFP in cardiac cholinergic nerves in preliminary experiments. Our goals for this study were to confirm our initial observation and perform a qualitative screen of other representative autonomic structures for the presences of GFP in cholinergic innervation of effector tissues. We evaluated GFP fluorescence of intact, unfixed tissues and the cellular localization of GFP and vesicular acetylcholine transporter (VAChT), a specific cholinergic marker, in tissue sections and intestinal whole mounts. Our experiments identified two major tissues where cholinergic neurons and/or nerve fibers lacked GFP: 1) most cholinergic neurons of the intrinsic cardiac ganglia and all cholinergic nerve fibers in the heart and 2) most cholinergic nerve fibers innervating airway smooth muscle. Most cholinergic neurons in airway ganglia stained for GFP. Cholinergic systems in the bladder and intestines were fully delineated by GFP staining. GFP labeling of input to ganglia with long preganglionic projections (vagal) was sparse or weak, while that to ganglia with short preganglionic projections (spinal) was strong. Total absence of GFP might be due to splicing out of the GFP gene. Lack of GFP in nerve projections from GFP-positive cell bodies might reflect a transport deficiency.

KEYWORDS:

ChAT(BAC)-eGFP transgenic mice; Cholinergic markers; Enteric nervous system; Immunohistochemistry; Intrinsic cardiac neurons; Parasympathetic nervous system

PMID:
29288022
PMCID:
PMC5878110
DOI:
10.1016/j.autneu.2017.12.005
[Indexed for MEDLINE]
Free PMC Article

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