Dataset Information

Component of nicotine-induced intracellular calcium elevation mediated through ?3- and ?5-containing nicotinic acetylcholine receptors are regulated by cyclic AMP in SH-SY 5Y cells.

ABSTRACT: The pathway from the medial habenular nucleus to the interpeduncular nucleus, in which nicotinic acetylcholine receptor (nAChR) including the ?3 and ?5 subunits (?3 * and ?5 * nAChRs) are expressed, is implicated in nicotine dependence. We investigated whether ?3 * and ?5 * nAChRs are regulated by cAMP using SH-SY5Y cells to clarify the significance of these receptors in nicotine dependence. We analyzed the nicotine-induced elevation of intracellular Ca2+ ([Ca2+]i). Nicotine induces a concentration-dependent increase in [Ca2+]i. The elimination of Ca2+ from extracellular fluid or intracellular stores demonstrated that the nicotine-induced [Ca2+]i elevation was due to extracellular influx and intracellular mobilization. The effects of tubocurarine on nicotine-induced [Ca2+]i elevation and current suggest that intracellular mobilization is caused by plasma membrane-permeating nicotine. The inhibition of ?3 *, ?5 *, ?7 nAChR and voltage-gated Ca2+ channels by using siRNAs and selective antagonists revealed the involvement of these nAChR subunits and channels in nicotine-induced [Ca2+]i elevation. To distinguish and characterize the ?3 * and ?5 * nAChR-mediated Ca2+ influx, we measured the [Ca2+]i elevation induced by nonmembrane-permeating acetylcholine when muscarinic receptors, ?7nAChR and Ca2+ channels were blocked. Under this condition, the [Ca2+]i elevation was significantly inhibited with a 48-h treatment of dibutyryl cAMP, which was accompanied by the downregulation of ?3 and ?4 mRNA. These findings suggest that ?3 * and ?5 * nAChR-mediated Ca2+ influx is possibly regulated by cAMP at the transcriptional level.

SUBMITTER: Takahashi T

PROVIDER: S-EPMC7703979 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Component of nicotine-induced intracellular calcium elevation mediated through α3- and α5-containing nicotinic acetylcholine receptors are regulated by cyclic AMP in SH-SY 5Y cells.

Takahashi Tamayo T Yoshida Takayuki T Harada Kana K Miyagi Tatsuhiko T Hashimoto Kouichi K Hide Izumi I Tanaka Shigeru S Irifune Masahiro M Sakai Norio N

PloS one 20201130 11

The pathway from the medial habenular nucleus to the interpeduncular nucleus, in which nicotinic acetylcholine receptor (nAChR) including the α3 and α5 subunits (α3 * and α5 * nAChRs) are expressed, is implicated in nicotine dependence. We investigated whether α3 * and α5 * nAChRs are regulated by cAMP using SH-SY5Y cells to clarify the significance of these receptors in nicotine dependence. We analyzed the nicotine-induced elevation of intracellular Ca2+ ([Ca2+]i). Nicotine induces a concentrat ...[more]

PMID: 33253222

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Project description:Allelic variation in CHRNA3, the gene encoding the α3 nicotinic acetylcholine receptor (nAChR) subunit, increases vulnerability to tobacco dependence and smoking-related diseases, but little is known about the role for α3-containing (α3*) nAChRs in regulating the addiction-related behavioral or physiological actions of nicotine. α3* nAChRs are densely expressed by medial habenula (mHb) neurons, which project almost exclusively to the interpeduncular nucleus (IPn) and are known to regulate nicotine avoidance behaviors. We found that Chrna3tm1.1Hwrt hypomorphic mice, which express constitutively low levels of α3* nAChRs, self-administer greater quantities of nicotine (0.4 mg kg-1 per infusion) than their wild-type littermates. Microinfusion of a lentivirus vector to express a short-hairpin RNA into the mHb or IPn to knock-down Chrna3 transcripts markedly increased nicotine self-administration behavior in rats (0.01-0.18 mg kg-1 per infusion). Using whole-cell recordings, we found that the α3β4* nAChR-selective antagonist α-conotoxin AuIB almost completely abolished nicotine-evoked currents in mHb neurons. By contrast, the α3β2* nAChR-selective antagonist α-conotoxin MII only partially attenuated these currents. Finally, micro-infusion of α-conotoxin AuIB (10 μm) but not α-conotoxin MII (10 μm) into the IPn in rats increased nicotine self-administration behavior. Together, these data suggest that α3β4* nAChRs regulate the stimulatory effects of nicotine on the mHb-IPn circuit and thereby regulate nicotine avoidance behaviors. These findings provide mechanistic insights into how CHRNA3 risk alleles can increase the risk of tobacco dependence and smoking-related diseases in human smokers.SIGNIFICANCE STATEMENT Allelic variation in CHRNA3, which encodes the α3 nicotinic acetylcholine receptor (nAChR) subunit gene, increases risk of tobacco dependence but underlying mechanisms are unclear. We report that Chrna3 hypomorphic mice consume greater quantities of nicotine than wild-type mice and that knock-down of Chrna3 gene transcripts in the habenula or interpeduncular nucleus (IPn) increases nicotine intake in rats. α-Conotoxin AuIB, a potent antagonist of the α3β4 nAChR subtype, reduced the stimulatory effects of nicotine on habenular neurons, and its infusion into the IPn increased nicotine intake in rats. These data suggest that α3β4 nAChRs in the habenula-IPn circuit regulate the motivational properties of nicotine.

Project description:Nicotine, the principal reinforcing compound in tobacco, acts in the brain by activating neuronal nicotinic acetylcholine receptors (nAChRs). This review summarizes our current knowledge regarding how the α5 accessory nAChR subunit, encoded by the CHRNA5 gene, differentially modulates α4β2* and α3β4* receptors at the cellular level. Genome-wide association studies have linked a gene cluster in chromosomal region 15q25 to increased susceptibility to nicotine addiction, lung cancer, chronic obstructive pulmonary disease, and peripheral arterial disease. Interestingly, this gene cluster contains a non-synonymous single-nucleotide polymorphism (SNP) in the human CHRNA5 gene, causing an aspartic acid (D) to asparagine (N) substitution at amino acid position 398 in the α5 nAChR subunit. Although other SNPs have been associated with tobacco smoking behavior, efforts have focused predominantly on the D398 and N398 variants in the α5 subunit. In recent years, significant progress has been made toward understanding the role that the α5 nAChR subunit-and the role of the D398 and N398 variants-plays on nAChR function at the cellular level. These insights stem primarily from a wide range of experimental models, including receptors expressed heterologously in Xenopus oocytes, various cell lines, and neurons derived from human induced pluripotent stem cells (iPSCs), as well as endogenous receptors in genetically engineered mice and-more recently-rats. Despite providing a wealth of available data, however, these studies have yielded conflicting results, and our understanding of the modulatory role that the α5 subunit plays remains incomplete. Here, we review these reports and the various techniques used for expression and analysis in order to examine how the α5 subunit modulates key functions in α4β2* and α3β4* receptors, including receptor trafficking, sensitivity, efficacy, and desensitization. In addition, we highlight the strikingly different role that the α5 subunit plays in Ca2+ signaling between α4β2* and α3β4* receptors, and we discuss whether the N398 α5 subunit variant can partially replace the D398 variant.

Dataset Information

Component of nicotine-induced intracellular calcium elevation mediated through ?3- and ?5-containing nicotinic acetylcholine receptors are regulated by cyclic AMP in SH-SY 5Y cells.

Publications

Component of nicotine-induced intracellular calcium elevation mediated through α3- and α5-containing nicotinic acetylcholine receptors are regulated by cyclic AMP in SH-SY 5Y cells.

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