Co-expression of GAD67 and choline acetyltransferase reveals a novel neuronal phenotype in the mouse medulla oblongata.

Jittima Gotts,Yuchio Yanagawa,Susan A Deuchars,Jim Deuchars,Lucy Atkinson,Ian J Edwards

doi:10.1016/j.autneu.2015.05.003

Jittima Gotts, Yuchio Yanagawa + Show 4 more

Open Access

https://doi.org/10.1016/j.autneu.2015.05.003

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Abstract

GABAergic and cholinergic systems play an important part in autonomic pathways. To determine the distribution of the enzymes responsible for the production of GABA and acetylcholine in areas involved in autonomic control in the mouse brainstem, we used a transgenic mouse expressing green fluorescent protein (GFP) in glutamate decarboxylase 67 (GAD67) neurones, combined with choline acetyl transferase (ChAT) immunohistochemistry. ChAT-immunoreactive (IR) and GAD67-GFP containing neurones were observed throughout the brainstem. A small number of cells contained both ChAT-IR and GAD67-GFP. Such double labelled cells were observed in the NTS (predominantly in the intermediate and central subnuclei), the area postrema, reticular formation and lateral paragigantocellular nucleus. All ChAT-IR neurones in the area postrema contained GAD67-GFP. Double labelled neurones were not observed in the dorsal vagal motor nucleus, nucleus ambiguus or hypoglossal nucleus. Double labelled ChAT-IR/GAD67-GFP cells in the NTS did not contain neuronal nitric oxide synthase (nNOS) immunoreactivity, whereas those in the reticular formation and lateral paragigantocellular nucleus did. The function of these small populations of double labelled cells is currently unknown, however their location suggests a potential role in integrating signals involved in oromotor behaviours.

Highlights

The dorsomedial medulla oblongata contains the nucleus tractus solitarius (NTS) and the area postrema (AP), areas which are both important in central control of a wide range of homeostatic reflexes (Loewy, 1990)
choline acetyl transferase (ChAT)-IR and glutamate decarboxylase 67 (GAD67)-green fluorescent protein (GFP) neurones are present in the NTS and a small number are double labelled
ChAT-IR neurones could be found throughout the subnuclei of the NTS

Summary

Introduction

The dorsomedial medulla oblongata contains the nucleus tractus solitarius (NTS) and the area postrema (AP), areas which are both important in central control of a wide range of homeostatic reflexes (Loewy, 1990). Two of the major neurotransmitters in the NTS and AP are ɣ-amino butyric acid (GABA) (Fong et al, 2005; Walberg and Ottersen, 1992) and acetylcholine (ACh) (Ruggiero et al, 1990; Tago et al, 1989), but their co-localisation has not been reported. Immunohistochemistry for GABA or its synthesising enzyme glutamate decarboxylase (GAD) 67 reveals GABAergic neurones and terminals throughout the NTS (Fong et al, 2005; Izzo et al, 1992; Kawai and Senba, 1999; Maqbool et al, 1991; Okada et al, 2008).

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