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Chemical Flavorants in Vaping Products Alter Neurobiology in a Sex-Dependent Manner to Promote Vaping-Related Behaviors. J Neurosci 2023; 43:1360-1374. [PMID: 36690450 PMCID: PMC9987575 DOI: 10.1523/jneurosci.0755-22.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/29/2022] [Accepted: 12/03/2022] [Indexed: 01/24/2023] Open
Abstract
Electronic nicotine delivery systems (ENDS) are distinctly different from combustible cigarettes because of the availability of flavor options. Subjective measures have been used to demonstrate that adults and adolescents prefer flavors for various reasons; (1) they are pleasing and (2) they mask the harshness of nicotine. Despite this, there have been few investigations into the molecular interactions that connect chemical flavorants to smoking or vaping-related behaviors. Here, we investigated the effects of three chemical flavorants (hexyl acetate, ethyl acetate, and methylbutyl acetate) that are found in green apple (GA) ENDS e-liquids but are also found in other flavor categories. We used a translationally relevant vapor self-administration mouse model and observed that adult male and female mice self-administered GA flavorants in the absence of nicotine. Using α4-mCherryα6-GFP nicotinic acetylcholine receptor (nAChR) mice, we observed that mice exposed to GA flavorants exhibited a sex-specific increase (upregulation) of nAChRs that was also brain-region specific. Electrophysiology revealed that mice exposed to GA flavorants exhibited enhanced firing of ventral tegmental area dopamine neurons. Fast-scan cyclic voltammetry revealed that electrically stimulated dopamine release in the nucleus accumbens core is increased in mice that are exposed to GA flavorants. These effects were similarly observed in the medial habenula. Overall, these findings demonstrate that ENDS flavors alone change neurobiology and may promote vaping-dependent behaviors in the absence of nicotine. Furthermore, the flavorant-induced changes in neurobiology parallel those caused by nicotine, which highlights the fact that nonmenthol flavorants may contribute to or enhance nicotine reward and reinforcement.SIGNIFICANCE STATEMENT The impact of flavors on vaping is a hotly debated topic; however, few investigations have examined this in a model that is relevant to vaping. Although a full understanding of the exact mechanism remains undetermined, our observations reveal that chemical flavorants in the absence of nicotine alter brain circuits relevant to vaping-related behavior. The fact that the flavorants investigated here exist in multiple flavor categories of vaping products highlights the fact that a multitude of flavored vaping products may pose a risk toward vaping-dependent behaviors even without the impact of nicotine. Furthermore, as the neurobiological changes have an impact on neurons of the reward system, there exists the possibility that nonmenthol flavorants may enhance nicotine reward and reinforcement.
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Li ZL, Gou CY, Wang WH, Li Y, Cui Y, Duan JJ, Chen Y. A novel effect of PDLIM5 in α7 nicotinic acetylcholine receptor upregulation and surface expression. Cell Mol Life Sci 2022; 79:64. [PMID: 35013841 PMCID: PMC11072317 DOI: 10.1007/s00018-021-04115-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are widespread throughout the central nervous system. Signaling through nAChRs contributes to numerous higher-order functions, including memory and cognition, as well as abnormalities such as nicotine addiction and neurodegenerative disorders. Although recent studies indicate that the PDZ-containing proteins comprising PSD-95 family co-localize with nicotinic acetylcholine receptors and mediate downstream signaling in the neurons, the mechanisms by which α7nAChRs are regulated remain unclear. Here, we show that the PDZ-LIM domain family protein PDLIM5 binds to α7nAChRs and plays a role in nicotine-induced α7nAChRs upregulation and surface expression. We find that chronic exposure to 1 μM nicotine upregulated α7, β2-contained nAChRs and PDLIM5 in cultured hippocampal neurons, and the upregulation of α7nAChRs and PDLIM5 is increased more on the cell membrane than the cytoplasm. Interestingly, in primary hippocampal neurons, α7nAChRs and β2nAChRs display distinct patterns of expression, with α7nAChRs colocalized more with PDLIM5. Furthermore, PDLIM5 interacts with α7nAChRs, but not β2nAChRs in native brain neurons. Knocking down of PDLIM5 in SH-SY5Y abolishes nicotine-induced upregulation of α7nAChRs. In primary hippocampal neurons, using shRNA against PDLIM5 decreased both surface clustering of α7nAChRs and α7nAChRs-mediated currents. Proteomics analysis and isothermal titration calorimetry (ITC) results show that PDLIM5 interacts with α7nAChRs through the PDZ domain, and the interaction between PDLIM5 and α7nAChRs can be promoted by nicotine. Collectively, our data suggest a novel cellular role of PDLIM5 in the regulation of α7nAChRs, which may be relevant to plastic changes in the nervous system.
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Affiliation(s)
- Zi-Lin Li
- Neurobiology Research Center, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, 518107, Guangdong, People's Republic of China
| | - Chen-Yu Gou
- Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzho, 510080, Guangdong, People's Republic of China
| | - Wen-Hui Wang
- Neurobiology Research Center, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, 518107, Guangdong, People's Republic of China
| | - Yuan Li
- Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzho, 510080, Guangdong, People's Republic of China
| | - Yu Cui
- Neurobiology Research Center, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, 518107, Guangdong, People's Republic of China
| | - Jing-Jing Duan
- Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzho, 510080, Guangdong, People's Republic of China.
- Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, Guangdong, People's Republic of China.
| | - Yuan Chen
- Neurobiology Research Center, School of Medicine, Shenzhen Campus of Sun Yat-Sen University, No. 66, Gongchang Road, Guangming District, Shenzhen, 518107, Guangdong, People's Republic of China.
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Patel VR, Salinas AM, Qi D, Gupta S, Sidote DJ, Goldschen-Ohm MP. Single-molecule imaging with cell-derived nanovesicles reveals early binding dynamics at a cyclic nucleotide-gated ion channel. Nat Commun 2021; 12:6459. [PMID: 34753946 PMCID: PMC8578382 DOI: 10.1038/s41467-021-26816-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/21/2021] [Indexed: 12/05/2022] Open
Abstract
Ligand binding to membrane proteins is critical for many biological signaling processes. However, individual binding events are rarely directly observed, and their asynchronous dynamics are occluded in ensemble-averaged measures. For membrane proteins, single-molecule approaches that resolve these dynamics are challenged by dysfunction in non-native lipid environments, lack of access to intracellular sites, and costly sample preparation. Here, we introduce an approach combining cell-derived nanovesicles, microfluidics, and single-molecule fluorescence colocalization microscopy to track individual binding events at a cyclic nucleotide-gated TAX-4 ion channel critical for sensory transduction. Our observations reveal dynamics of both nucleotide binding and a subsequent conformational change likely preceding pore opening. Kinetic modeling suggests that binding of the second ligand is either independent of the first ligand or exhibits up to ~10-fold positive binding cooperativity. This approach is broadly applicable to studies of binding dynamics for proteins with extracellular or intracellular domains in native cell membrane.
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Affiliation(s)
- Vishal R Patel
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
- Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Arturo M Salinas
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Darong Qi
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
| | - Shipra Gupta
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
| | - David J Sidote
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
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Fu X, Moonschi FH, Fox-Loe AM, Snell AA, Hopkins DM, Avelar AJ, Henderson BJ, Pauly JR, Richards CI. Brain Region Specific Single-Molecule Fluorescence Imaging. Anal Chem 2019; 91:10125-10131. [PMID: 31298524 DOI: 10.1021/acs.analchem.9b02133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We developed an approach utilizing nanoscale vesicles extracted from brain regions combined with single molecule imaging to monitor how an animal's physiological condition regulates the dynamics of protein distributions in different brain regions. This method was used to determine the effect of nicotine on the distribution of receptor stoichiometry in different mouse brain regions. Nicotine-induced upregulation of α4β2 nicotinic acetylcholine receptors (nAChRs) is associated with changes in their expression, trafficking, and stoichiometry. The structural assembly of nAChRs has been quantified in cell culture based systems using single molecule techniques. However, these methods are not capable of quantifying biomolecule assembly that takes place in a live animal. Both nicotine-induced upregulation and changes in nAChR stoichiometry differ across brain regions. Our single molecule approach revealed that nicotine acts differentially across brain regions to alter assembly in response to exposure and withdrawal.
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Affiliation(s)
- Xu Fu
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , United States
| | - Faruk H Moonschi
- Department of Physiology , University of Kentucky , Lexington , Kentucky 40536 , United States
| | - Ashley M Fox-Loe
- Department of Chemistry , Slippery Rock University , Slippery Rock , Pennsylvania 16057 , United States
| | - Aaron A Snell
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , United States
| | - Deann M Hopkins
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Kentucky , Lexington , Kentucky 40508 , United States
| | - Alicia J Avelar
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine , Marshall University , Huntington , West Virginia 25755 , United States
| | - Brandon J Henderson
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine , Marshall University , Huntington , West Virginia 25755 , United States
| | - James R Pauly
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Kentucky , Lexington , Kentucky 40508 , United States
| | - Christopher I Richards
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , United States
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Moonschi FH, Fox-Loe AM, Fu X, Richards CI. Mammalian Cell-derived Vesicles for the Isolation of Organelle Specific Transmembrane Proteins to Conduct Single Molecule Studies. Bio Protoc 2018; 8:e2825. [PMID: 30406159 DOI: 10.21769/bioprotoc.2825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cell-derived vesicles facilitate the isolation of transmembrane proteins in their physiological membrane maintaining their structural and functional integrity. These vesicles can be generated from different cellular organelles producing, housing, or transporting the proteins. Combined with single-molecule imaging, isolated organelle specific vesicles can be employed to study the trafficking and assembly of the embedded proteins. Here we present a method for organelle specific single molecule imaging via isolation of ER and plasma membrane vesicles from HEK293T cells by employing OptiPrep gradients and nitrogen cavitation. The isolation was validated through Western blotting, and the isolated vesicles were used to perform single molecule studies of oligomeric receptor assembly.
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Affiliation(s)
- Faruk H Moonschi
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
| | - Ashley M Fox-Loe
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
| | - Xu Fu
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
| | - Chris I Richards
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
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