Organisation of enkephalin inputs and outputs of the central nucleus of the amygdala in mice

Aida Viden; Sarah S Ch'ng; Leigh C Walker; Arnav Shesham; Sabine M Hamilton; Craig M Smith; Andrew J Lawrence

doi:10.1016/j.jchemneu.2022.102167

Organisation of enkephalin inputs and outputs of the central nucleus of the amygdala in mice

J Chem Neuroanat. 2022 Nov:125:102167. doi: 10.1016/j.jchemneu.2022.102167. Epub 2022 Sep 28.

Authors

Aida Viden¹, Sarah S Ch'ng¹, Leigh C Walker², Arnav Shesham³, Sabine M Hamilton⁴, Craig M Smith⁴, Andrew J Lawrence⁵

Affiliations

¹ Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia.
² Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia.
³ Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia; Department of Physiology, Monash University, Clayton, VIC 3800, Australia.
⁴ School of Medicine, IMPACT, Institute for Innovation in Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, VIC 3216, Australia.
⁵ Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia. Electronic address: Andrew.Lawrence@florey.edu.au.

PMID: 36182026
DOI: 10.1016/j.jchemneu.2022.102167

Abstract

The central nucleus of the amygdala (CeA) is a key hub integrating sensory inputs and modulating behavioural outputs. The CeA is a complex structure with discrete subdivisions, high peptidergic heterogeneity and broad CNS afferent and efferent projections. While several neuropeptide systems within the CeA have been examined in detail, less is known about CeA preproenkephalin (ppENK) cells. Here, we used a recently developed transgenic Penk-Cre mouse line to advance our understanding of the efferent and afferent connectivity of ppENK in the CeA. First, to determine the fidelity of Cre expression in Penk-Cre transgenic mice, we conducted RNAscope in the CeA of Penk-Cre mice. Our analysis revealed that 96.6 % of CeA Cre+ neurons co-expressed pENK mRNA, and 99.7 % of CeA pENK+ neurons co-expressed Cre mRNA, indicating faithful recapitulation of Cre expression in CeA ppENK-expressing cells, supporting the fidelity of the Penk-Cre reporter mouse. Anterograde tracing of CeA^Penk cells showed strong efferent projections to the extended amygdala, midbrain and hindbrain PBN and NTS. Retrograde tracing of Penk afferents to the CeA were more restricted, with primary innervation originating within the amygdala complex and bed nucleus of the stria terminalis, and minor innervation from the parabrachial nucleus and nucleus of the solitary tract. Together, our data provide a comprehensive map of ENKergic efferent and afferent connectivity of the CeA in Penk-Cre mice. Further, we highlight both the utility and limitations of the Penk-Cre mice to study the function of CeA, PBN and NTS ppENK cells.

Keywords: Afferent; Central amygdala; Connectivity; Efferent; Enkephalin; Penk-Cre.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Central Amygdaloid Nucleus* / metabolism
Enkephalins / genetics
Enkephalins / metabolism
Mice
Neurons / metabolism
RNA, Messenger / metabolism

Substances

Enkephalins
RNA, Messenger