Acute Ethanol Administration Upregulates Synaptic α4-Subunit of Neuronal Nicotinic Acetylcholine Receptors within the Nucleus Accumbens and Amygdala
Abstract
Alcohol and nicotine are two of the most frequently abused drugs, with their comorbidity well described. Previous data show that chronic exposure to nicotine upregulates high-affinity nicotinic acetylcholine receptors (nAChRs) in several brain areas. Effects of ethanol on specific brain nAChR subtypes within the mesolimbic dopaminergic (DA) pathway may be a key element in the comorbidity of ethanol and nicotine. However, it is unknown how alcohol affects the abundance of these receptor proteins. In the present study, we measured the effect of acute binge ethanol on nAChR α4 subunit levels in the prefrontal cortex (PFC), nucleus accumbens (NAc), ventral tegmental area (VTA), and amygdala (Amg) by western blot analysis using a knock-in mouse line, generated with a normally functioning α4 nAChR subunit tagged with yellow fluorescent protein (YFP). We observed a robust increase in α4-YFP subunit levels in the NAc and the Amg following acute ethanol, with no changes in the PFC and VTA. To further investigate whether this upregulation was mediated by increased local mRNA transcription, we quantified mRNA levels of the Chrna4 gene using qRT-PCR. We found no effect of ethanol on α4 mRNA expression, suggesting that the upregulation of α4 protein rather occurs post-translationally. The quantitative counting of YFP immunoreactive puncta further revealed that α4-YFP protein is upregulated in presynaptic boutons of the dopaminergic axons projecting to the shell and the core regions of the NAc as well as to the basolateral amygdala (BLA), but not to the central or lateral Amg. Together, our results demonstrate that a single exposure to binge ethanol upregulates level of synaptic α4∗ nAChRs in dopaminergic inputs to the NAc and BLA. This upregulation could be linked to the functional dysregulation of dopaminergic signalling observed during the development of alcohol dependence.
Additional Information
© 2017 Tarren, Lester, Belmer and Bartlett. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Received: 03 July 2017; Accepted: 05 October 2017; Published: 24 October 2017. Author Contributions: HL provided the α4YFP mice and revised the manuscript. JT performed the WB and qPCR experiments and analysis, and drafted the manuscript. AB performed the IHC experiments and analysis. JT, AB, and SB analyzed and interpreted the results. JT, AB, and SB designed the experiments and revised the manuscript. All authors approved the final version of the manuscript. Funding: National Health and Medical Research Council (NHMRC), GNT104942 and GNT 1061979 to SB; Australian Research Council (ARC) FT1110884 to SB. US National Institutes of Health DA037161 to HL. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. We thank Ms. Joan Holgate for excellent technical assistance and advice, as well as for animal ethics and breeding. We are grateful to the imaging facility of the Translational Research Institute and the facility manager Sandrine Roy for the extensive use of resources. We also thank Mick Grohuk for his assistance with manuscript formatting. We acknowledge the National Health and Medical Research Council and the Australian Research Council for funding of this work.Attached Files
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Additional details
- PMCID
- PMC5660714
- Eprint ID
- 83149
- Resolver ID
- CaltechAUTHORS:20171113-110814227
- GNT 104942
- National Health and Medical Research Council (NHMRC)
- GNT 1061979
- National Health and Medical Research Council (NHMRC)
- FT1110884
- Australian Research Council
- DA037161
- NIH
- Created
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2017-11-14Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field