Molecular and cellular characterization of nicotinic acetylcholine receptor subtypes in the arcuate nucleus of the mouse hypothalamus. (19th June 2018)

• Record Type: Journal Article
• Authors: Calarco, Cali A.; Li, Zhiying; Taylor, Seth R.; Lee, Somin; Zhou, Wenliang; Friedman, Jeffrey M.; Mineur, Yann S.; Gotti, Cecilia; Picciotto, Marina R.
• Is Part Of: European journal of neuroscience. Volume 48:Number 1(2018)
• Page Start: 1600
• Page End: 1619
• Publication Date: 2018-06-19
• Subjects: AgRP -- ARC -- food intake -- nAChR subunits -- nicotine -- POMC; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.13966
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: Nicotine, acting through nicotinic acetylcholine receptors (nAChRs), increases the firing rate of both orexigenic agouti‐related peptide (AgRP) and anorexigenic pro‐opiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARC), yet nicotine and other nAChR agonists decrease food intake in mice. Viral‐mediated knockdown of the β4 nAChR subunit in all neuronal cell types in the ARC prevents the nicotinic agonist cytisine from decreasing food intake, but it is not known whether the β4 subunit is selectively expressed in anorexigenic neurons or how other nAChR subtypes are distributed in this nucleus. Using translating ribosome affinity purification (TRAP) on ARC tissue from mice with ribosomes tagged in either AgRP or POMC cells, we examined nAChR subunit mRNA levels using real‐time PCR. Both AgRP and POMC cells express a comparable panel of nAChR subunits with differences in α7 mRNA levels and a trend for difference in α4 levels, but no differences in β4 expression. Immunoprecipitation of assembled nAChRs revealed that the β4 subunit forms assembled channels with α3, β2 and α4, but not other subunits found in the ARC. Finally, using cell type‐selective, virally delivered small hairpin RNAs targeting either the β4 or α7 subunit, we examined the contribution of each subunit in either AgRP or POMC cells to the behavioural response to nicotine, refining the understanding of nicotinic regulation of this feeding circuit. These experiments identify a more complex set of nAChRs expressed in ARC than in other hypothalamic regions. Thus, the ARC appears to be a particular target of nicotinic modulation. Abstract : Nicotinic acetylcholine receptor (nAChR) signalling on both anorexigenic and orexigenic neurons in the arcuate nucleus of the hypothalamus (ARC) regulates the effects of nicotine on food intake. nAChR subunit expression is not segregated by cell type, the β4 subunit assembles into nAChRs with a different composition than in other β4 containing brain regions, and cell type‐selective knockdown of the β4 subunit in either anorexigenic and orexigenic cells in the ARC blocks the reduction in feeding due to nicotine.