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Kim H, Kim M, Jang Y. Inhaled Volatile Molecules-Responsive TRP Channels as Non-Olfactory Receptors. Biomol Ther (Seoul) 2024; 32:192-204. [PMID: 37551139 PMCID: PMC10902705 DOI: 10.4062/biomolther.2023.118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/08/2023] [Accepted: 07/12/2023] [Indexed: 08/09/2023] Open
Abstract
Generally, odorant molecules are detected by olfactory receptors, which are specialized chemoreceptors expressed in olfactory neurons. Besides odorant molecules, certain volatile molecules can be inhaled through the respiratory tract, often leading to pathophysiological changes in the body. These inhaled molecules mediate cellular signaling through the activation of the Ca2+-permeable transient receptor potential (TRP) channels in peripheral tissues. This review provides a comprehensive overview of TRP channels that are involved in the detection and response to volatile molecules, including hazardous substances, anesthetics, plant-derived compounds, and pheromones. The review aims to shed light on the biological mechanisms underlying the sensing of inhaled volatile molecules. Therefore, this review will contribute to a better understanding of the roles of TRP channels in the response to inhaled molecules, providing insights into their implications for human health and disease.
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Affiliation(s)
- Hyungsup Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Minwoo Kim
- Department of Medical and Digital Engineering, College of Engineering, Hanyang University, Seoul 04736, Republic of Korea
| | - Yongwoo Jang
- Department of Medical and Digital Engineering, College of Engineering, Hanyang University, Seoul 04736, Republic of Korea
- Department of Pharmacology, College of Medicine, Hanyang University, Seoul 04736, Republic of Korea
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Margulis E, Lang T, Tromelin A, Ziaikin E, Behrens M, Niv MY. Bitter Odorants and Odorous Bitters: Toxicity and Human TAS2R Targets. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37263600 DOI: 10.1021/acs.jafc.3c00592] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Flavor is perceived through the olfactory, taste, and trigeminal systems, mediated by designated GPCRs and channels. Signal integration occurs mainly in the brain, but some cross-reactivities occur at the receptor level. Here, we predict potential bitterness and taste receptors targets for thousands of odorants. BitterPredict and BitterIntense classifiers suggest that 3-9% of flavor and food odorants have bitter taste, but almost none are intensely bitter. About 14% of bitter molecules are expected to have an odor. Bitterness is more common for unpleasant smells such as fishy, amine, and ammoniacal, while non-bitter odorants often have pleasant smells. Experimental toxicity values suggest that fishy ammoniac smells are more toxic than pleasant smells, regardless of bitterness. TAS2R14 is predicted as the main bitter receptor for odorants, confirmed by in vitro profiling of 10 odorants. The activity of bitter odorants may have implications for physiology due to ectopic expression of taste and smell receptors.
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Affiliation(s)
- Eitan Margulis
- Food Science and Nutrition, The Robert H Smith Faculty of Agriculture, Food and Environment, The Institute of Biochemistry, Food and Nutrition, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - Tatjana Lang
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Anne Tromelin
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne Franche-Comté, F-21000 Dijon, France
| | - Evgenii Ziaikin
- Food Science and Nutrition, The Robert H Smith Faculty of Agriculture, Food and Environment, The Institute of Biochemistry, Food and Nutrition, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - Maik Behrens
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Masha Y Niv
- Food Science and Nutrition, The Robert H Smith Faculty of Agriculture, Food and Environment, The Institute of Biochemistry, Food and Nutrition, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
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3
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Molot J, Sears M, Anisman H. Multiple Chemical Sensitivity: It's time to catch up to the science. Neurosci Biobehav Rev 2023; 151:105227. [PMID: 37172924 DOI: 10.1016/j.neubiorev.2023.105227] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 05/06/2023] [Indexed: 05/15/2023]
Abstract
Multiple chemical sensitivity (MCS) is a complex medical condition associated with low dose chemical exposures. MCS is characterized by diverse features and common comorbidities, including fibromyalgia, cough hypersensitivity, asthma, and migraine, and stress/anxiety, with which the syndrome shares numerous neurobiological processes and altered functioning within diverse brain regions. Predictive factors linked to MCS comprise genetic influences, gene-environment interactions, oxidative stress, systemic inflammation, cell dysfunction, and psychosocial influences. The development of MCS may be attributed to the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1. Capsaicin inhalation challenge studies demonstrated that TRPV1 sensitization is manifested in MCS, and functional brain imaging studies revealed that TRPV1 and TRPA1 agonists promote brain-region specific neuronal variations. Unfortunately, MCS has often been inappropriately viewed as stemming exclusively from psychological disturbances, which has fostered patients being stigmatized and ostracized, and often being denied accommodation for their disability. Evidence-based education is essential to provide appropriate support and advocacy. Greater recognition of receptor-mediated biological mechanisms should be incorporated in laws, and regulation of environmental exposures.
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Affiliation(s)
- John Molot
- Family Medicine, University of Ottawa Faculty of Medicine, Ottawa ON Canada; Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Neuroscience, Carleton University, Ottawa Canada.
| | - Margaret Sears
- Family Medicine, University of Ottawa Faculty of Medicine, Ottawa ON Canada; Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Neuroscience, Carleton University, Ottawa Canada.
| | - Hymie Anisman
- Family Medicine, University of Ottawa Faculty of Medicine, Ottawa ON Canada; Ottawa Hospital Research Institute, Ottawa, ON, Canada; Department of Neuroscience, Carleton University, Ottawa Canada.
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4
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Li H, Lee C, Kay LM. Testing effects of trigeminal stimulation on binary odor mixture quality in rats. Front Neurosci 2023; 17:1059741. [PMID: 36960175 PMCID: PMC10027748 DOI: 10.3389/fnins.2023.1059741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 02/16/2023] [Indexed: 03/09/2023] Open
Abstract
Prior attempts at forming theoretical predictions regarding the quality of binary odor mixtures have failed to find any consistent predictor for overshadowing of one component in a binary mixture by the other. We test here the hypothesis that trigeminality contributes to overshadowing effects in binary mixture perception. Most odorants stimulate the trigeminal nerve in the nasal sensory epithelium. In the current study we test rats' ability to detect component odorants in four binary odor sets chosen for their relative trigeminality. We predicted that the difference in trigeminal intensity would predict the degree of overshadowing by boosting or suppressing perceptual intensity of these odorants during learning or during mixture perception. We used a two-alternative choice (TAC) task in which rats were trained to recognize the two components of each mixture and tested on a range of mixtures of the two without reinforcement. We found that even though odorant concentrations were adjusted to balance volatility, all odor sets produced asymmetric psychometric curves. Odor pairs with the greatest difference in trigeminality showed overshadowing by the odorant with weaker trigeminal properties. Odor sets with more evenly matched trigeminal properties also showed asymmetry that was not predicted by either small differences in volatility or trigeminality. Thus, trigeminal properties may influence overshadowing in odor mixtures, but other factors are also likely involved. These mixed results further support the need to test each odor mixture to determine its odor quality and underscore recent results at the level of olfactory receptor neurons that show massive and unpredictable inhibition among odorants in complex mixtures.
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Affiliation(s)
- Huibo Li
- Department of Psychology, The University of Chicago, Chicago, IL, United States
- Institute for Mind and Biology, The University of Chicago, Chicago, IL, United States
| | - Clara Lee
- The College, The University of Chicago, Chicago, IL, United States
| | - Leslie M. Kay
- Department of Psychology, The University of Chicago, Chicago, IL, United States
- Institute for Mind and Biology, The University of Chicago, Chicago, IL, United States
- The College, The University of Chicago, Chicago, IL, United States
- *Correspondence: Leslie M. Kay,
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5
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Alhadyan SK, Sivaraman V, Onyenwoke RU. E-cigarette Flavors, Sensory Perception, and Evoked Responses. Chem Res Toxicol 2022; 35:2194-2209. [PMID: 36480683 DOI: 10.1021/acs.chemrestox.2c00268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The chemosensory experiences evoked by flavors encompass a number of unique sensations that include olfactory stimuli (smell), gustatory stimuli (taste, i.e., salty, sweet, sour, bitter, and umami (also known as "savoriness")), and chemesthesis (touch). As such, the responses evoked by flavors are complex and, as briefly stated above, involve multiple perceptive mechanisms. The practice of adding flavorings to tobacco products dates back to the 17th century but is likely much older. More recently, the electronic cigarette or "e-cigarette" and its accompanying flavored e-liquids emerged on to the global market. These new products contain no combustible tobacco but often contain large concentrations (reported from 0 to more than 50 mg/mL) of nicotine as well as numerous flavorings and/or flavor chemicals. At present, there are more than 400 e-cigarette brands available along with potentially >15,000 different/unique flavored products. However, surprisingly little is known about the flavors/flavor chemicals added to these products, which can account for >1% by weight of some e-liquids, and their resultant chemosensory experiences, and the US FDA has done relatively little, until recently, to regulate these products. This article will discuss e-cigarette flavors and flavor chemicals, their elicited responses, and their sensory effects in some detail.
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Affiliation(s)
- Shatha K Alhadyan
- Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707, United States
| | - Vijay Sivaraman
- Department of Biological and Biomedical Sciences, North Carolina Central University, Durham, North Carolina 27707, United States
| | - Rob U Onyenwoke
- Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707, United States.,Biomanufacturing Research Institute and Technology Enterprise (BRITE), North Carolina Central University, Durham, North Carolina 27707, United States
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6
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Molot J, Sears M, Marshall LM, Bray RI. Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity. REVIEWS ON ENVIRONMENTAL HEALTH 2022; 37:509-530. [PMID: 34529912 DOI: 10.1515/reveh-2021-0043] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 08/13/2021] [Indexed: 05/23/2023]
Abstract
The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.
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Affiliation(s)
- John Molot
- Family Medicine, University of Ottawa Faculty of Medicine, North York, ON, Canada
| | | | | | - Riina I Bray
- Family and Community Medicine, University of Toronto, Toronto, ON, Canada
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Ha T, Kim MS, Kang B, Kim K, Hong SS, Kang T, Woo J, Han K, Oh U, Choi CW, Hong GS. Lotus Seed Green Embryo Extract and a Purified Glycosyloxyflavone Constituent, Narcissoside, Activate TRPV1 Channels in Dorsal Root Ganglion Sensory Neurons. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:3969-3978. [PMID: 35343690 DOI: 10.1021/acs.jafc.1c07724] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Several studies have documented the broad-spectrum bioactivities of a lotus seed (Plumula nelumbinis [PN]) green embryo extract. However, the specific bioactive components and associated molecular mechanisms remain largely unknown. This study aimed to identify the ion channel-activating mechanisms of PN extracts. Using fluorometric imaging and patch-clamp recordings, PN extracts were screened for calcium channel activation in dorsal root ganglion (DRG) neurons. The TRPV1 channels in DRG neurons were strongly activated by the PN extract (mean amplitude of 131 ± 45 pA at 200 μg/mL) and its purified glycosyloxyflavone narcissoside (401 ± 271 pA at 100 μM). Serial treatment with a 200 μg/mL PN extract in TRPV1-overexpressing HEK293T cells induced robust desensitization to 10 ± 10% of the initial current amplitude. Thus, we propose that the PN extract and narcissoside function as TRPV1 agonists. This new finding may advance our knowledge regarding the traditional and scientific functions of PN in human health and disease.
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Affiliation(s)
- Taewoong Ha
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Mi-Sun Kim
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Bokeum Kang
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Kyungmin Kim
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Seong Su Hong
- Natural Product Research Team, Gyeonggi Biocenter, Gyeonggido Business and Science Accelerator, Gyeonggi-Do 16229, Republic of Korea
| | - Taek Kang
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Junhyuk Woo
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Kyungreem Han
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Uhtaek Oh
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Chun Whan Choi
- Natural Product Research Team, Gyeonggi Biocenter, Gyeonggido Business and Science Accelerator, Gyeonggi-Do 16229, Republic of Korea
| | - Gyu-Sang Hong
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology, Seoul 02792, Republic of Korea
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8
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Oka Y, Takahashi K, Ohta T. The effects of vanilloid analogues structurally related to capsaicin on the transient receptor potential vanilloid 1 channel. Biochem Biophys Rep 2022; 30:101243. [PMID: 35280525 PMCID: PMC8914335 DOI: 10.1016/j.bbrep.2022.101243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 11/30/2022] Open
Abstract
Transient receptor potential vanilloid 1 (TRPV1) is known as a receptor of capsaicin, a spicy ingredient of chili peppers. It is also sensitive to a variety of pungent compounds and is involved in nociception. Here, we focused on the structural characteristics of capsaicin, and investigated whether vanillylmanderic acid (VMA), vanillic acid (VAcid), vanillyl alcohol (VAlc), vanillyl butyl ether (VBE), and vanillin, containing a vanillyl skeleton similar to capsaicin, affected the TRPV1 activities. For detection of TRPV1 activity, intracellular Ca2+ concentration ([Ca2+]i) was measured in HEK 293 cells heterologously expressing mouse TRPV1 (mTRPV1-HEK) and in mouse sensory neurons. Except for vanillin, four vanilloid analogues dose-dependently increased [Ca2+]i in mTRPV1-HEK. The solutions that dissolved VMA, VAcid and vanillin at high concentrations were acidic, whereas those of VAlc and VBE were neutral. Neutralized VAcid evoked [Ca2+]i increases but neutralized VMA did not. Mutation of capsaicin-sensing sites diminished [Ca2+]i responses to VAcid, VAlc and VBE. VAcid, VMA, and vanillin suppressed the activation of TRPV1 induced by capsaicin. VAcid and VMA also inhibited the acid-induced TRPV1 activation. In sensory neurons, VMA diminished TRPV1 activation by capsaicin or acids. The present data indicate that these structural characteristics of chemical compounds on TRPV1 may provide strategies for the development of novel analgesic drugs targeting nociceptive TRPV1.
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Key Words
- Catecholamine metabolites
- DMSO, Dimethyl sulfoxide
- DRG, Dorsal root ganglion
- HEK, Human embryonic kidney
- Heterologous expression
- Intracellular Ca2+ concentration
- Mutagenesis
- Sensory neurons
- TRPV, Transient receptor potential vanilloid 1
- VAcid, Vanillic acid
- VBE, Vanillyl butyl ether
- VMA, Vanillylmandelic acid
- Valc, Vanillyl alcohol
- Vanillyl structure
- [Ca2+], Intracellular Ca2+ concentration
- mTRPV1, Mouse TRPV1
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Affiliation(s)
- Y Oka
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - K Takahashi
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan.,Joint Graduate School of Veterinary Sciences, Gifu University, Tottori University, Tottori, Japan
| | - T Ohta
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan.,Joint Graduate School of Veterinary Sciences, Gifu University, Tottori University, Tottori, Japan
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9
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Involvement of nasal trigeminal function in human stereo smelling. Proc Natl Acad Sci U S A 2020; 117:25979. [PMID: 33024013 DOI: 10.1073/pnas.2016043117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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10
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Vijayaraghavan R, Deb U, Gutch PK. Effect of dibenz(b,f)-1,4-oxazepine aerosol on the breathing pattern and respiratory variables by continuous recording and analysis in unanaesthetised mice. Toxicol Rep 2020; 7:1121-1126. [PMID: 32953463 PMCID: PMC7486425 DOI: 10.1016/j.toxrep.2020.08.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/19/2020] [Accepted: 08/23/2020] [Indexed: 12/02/2022] Open
Abstract
Dibenz (b,f)-1,4-oxazepine (CR) is a riot control agent. Respiratory variables and breathing pattern were recorded continuously in mice. CR produced concentration dependent sensory irritation without pulmonary irritation. Concentrations below 158.2 mg/m3 showed recovery to normal breathing. Study shows CR causes sensory irritation only and may not cause lung injury.
A riot control agent has to be a sensory irritant of a reversible type without pulmonary irritation as the later can cause lung injury. The aim of the present study is to continuously record and analyse breathing pattern and respiratory variables of dibenz (b,f)-1,4-oxazepine (CR) in unanaesthetised mice during and after exposure. The lowest concentration of 0.65 mg/m3 did not produce any effect on the breathing pattern. As high as 500 fold increase (315.9 mg/m3) in the concentration was used and no mortality was observed. CR produced a concentration dependent sensory irritation, without pulmonary irritation or airflow obstruction, showing that it may not cause any lung injury. The sensory irritation was initiated within 5 min of exposure due to the activation of TRPA1 receptors of the upper respiratory tract. Immediate recovery of normal breath without sensory irritation was observed in all the concentrations except the highest concentration of 315.9 mg/m3. Corresponding to the sensory irritation there was concentration dependent respiratory depression. The 50 percent respiratory depression (RD50) in this experiment was 152 mg/m3 and the estimated threshold limit value for occupational exposure was 4.56 mg/m3. The present study shows that CR causes sensory irritation only which is completely recoverable.
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Affiliation(s)
| | - Utsab Deb
- Defence Research Laboratory, Tezpur, 784001, India
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Hossain MZ, Ando H, Unno S, Kitagawa J. Targeting Chemosensory Ion Channels in Peripheral Swallowing-Related Regions for the Management of Oropharyngeal Dysphagia. Int J Mol Sci 2020; 21:E6214. [PMID: 32867366 PMCID: PMC7503421 DOI: 10.3390/ijms21176214] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 12/22/2022] Open
Abstract
Oropharyngeal dysphagia, or difficulty in swallowing, is a major health problem that can lead to serious complications, such as pulmonary aspiration, malnutrition, dehydration, and pneumonia. The current clinical management of oropharyngeal dysphagia mainly focuses on compensatory strategies and swallowing exercises/maneuvers; however, studies have suggested their limited effectiveness for recovering swallowing physiology and for promoting neuroplasticity in swallowing-related neuronal networks. Several new and innovative strategies based on neurostimulation in peripheral and cortical swallowing-related regions have been investigated, and appear promising for the management of oropharyngeal dysphagia. The peripheral chemical neurostimulation strategy is one of the innovative strategies, and targets chemosensory ion channels expressed in peripheral swallowing-related regions. A considerable number of animal and human studies, including randomized clinical trials in patients with oropharyngeal dysphagia, have reported improvements in the efficacy, safety, and physiology of swallowing using this strategy. There is also evidence that neuroplasticity is promoted in swallowing-related neuronal networks with this strategy. The targeting of chemosensory ion channels in peripheral swallowing-related regions may therefore be a promising pharmacological treatment strategy for the management of oropharyngeal dysphagia. In this review, we focus on this strategy, including its possible neurophysiological and molecular mechanisms.
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Affiliation(s)
- Mohammad Zakir Hossain
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Hiroshi Ando
- Department of Biology, School of Dentistry, Matsumoto Dental University, 1780 Gobara, Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Shumpei Unno
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
| | - Junichi Kitagawa
- Department of Oral Physiology, School of Dentistry, Matsumoto Dental University, 1780 Gobara Hirooka, Shiojiri, Nagano 399-0781, Japan;
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12
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Patten T, De Biasi M. History repeats itself: Role of characterizing flavors on nicotine use and abuse. Neuropharmacology 2020; 177:108162. [PMID: 32497589 DOI: 10.1016/j.neuropharm.2020.108162] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/22/2020] [Accepted: 05/24/2020] [Indexed: 12/13/2022]
Abstract
The popularity of e-cigarettes has skyrocketed in recent years, and most vapers use flavored e-cigarette products. Consumption of flavored e-cigarettes exceeds that of combustible cigarettes and other tobacco products among adolescents, who are particularly vulnerable to becoming nicotine dependent. Flavorings have been used by the tobacco industry since the 17th century, but the use of flavors by the e-cigarette industry to create products with "characterizing" flavors (i.e. flavors other than tobacco or menthol) has sparked a public health debate. This review addresses the possibility that characterizing flavors make nicotine more appealing, rewarding and addictive. It also discusses ways in which preclinical and clinical studies could improve our understanding of the mechanisms by which flavors may alter nicotine reward and reinforcement. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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Affiliation(s)
- Theresa Patten
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Mariella De Biasi
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
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13
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Erythropel HC, Jabba SV, DeWinter TM, Mendizabal M, Anastas PT, Jordt SE, Zimmerman JB. Formation of flavorant-propylene Glycol Adducts With Novel Toxicological Properties in Chemically Unstable E-Cigarette Liquids. Nicotine Tob Res 2020; 21:1248-1258. [PMID: 30335174 DOI: 10.1093/ntr/nty192] [Citation(s) in RCA: 126] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/13/2018] [Indexed: 12/12/2022]
Abstract
INTRODUCTION "Vaping" electronic cigarettes (e-cigarettes) is increasingly popular with youth, driven by the wide range of available flavors, often created using flavor aldehydes. The objective of this study was to examine whether flavor aldehydes remain stable in e-cigarette liquids or whether they undergo chemical reactions, forming novel chemical species that may cause harm to the user. METHODS Gas chromatography was used to determine concentrations of flavor aldehydes and reaction products in e-liquids and vapor generated from a commercial e-cigarette. Stability of the detected reaction products in aqueous media was monitored by ultraviolet spectroscopy and nuclear magnetic resonance spectroscopy, and their effects on irritant receptors determined by fluorescent calcium imaging in HEK-293T cells. RESULTS Flavor aldehydes including benzaldehyde, cinnamaldehyde, citral, ethylvanillin, and vanillin rapidly reacted with the e-liquid solvent propylene glycol (PG) after mixing, and upward of 40% of flavor aldehyde content was converted to flavor aldehyde PG acetals, which were also detected in commercial e-liquids. Vaping experiments showed carryover rates of 50%-80% of acetals to e-cigarette vapor. Acetals remained stable in physiological aqueous solution, with half-lives above 36 hours, suggesting they persist when inhaled by the user. Acetals activated aldehyde-sensitive TRPA1 irritant receptors and aldehyde-insensitive TRPV1 irritant receptors. CONCLUSIONS E-liquids are potentially reactive chemical systems in which new compounds can form after mixing of constituents and during storage, as demonstrated here for flavor aldehyde PG acetals, with unexpected toxicological effects. For regulatory purposes, a rigorous process is advised to monitor the potentially changing composition of e-liquids and e-vapors over time, to identify possible health hazards. IMPLICATIONS This study demonstrates that e-cigarette liquids can be chemically unstable, with reactions occurring between flavorant and solvent components immediately after mixing at room temperature. The resulting compounds have toxicological properties that differ from either the flavorants or solvent components. These findings suggest that the reporting of manufacturing ingredients of e-liquids is insufficient for a safety assessment. The establishment of an analytical workflow to detect newly formed compounds in e-liquids and their potential toxicological effects is imperative for regulatory risk analysis.
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Affiliation(s)
- Hanno C Erythropel
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT.,Yale Tobacco Center of Regulatory Science, Department of Psychiatry, Yale School of Medicine, New Haven, CT
| | - Sairam V Jabba
- Yale Tobacco Center of Regulatory Science, Department of Psychiatry, Yale School of Medicine, New Haven, CT.,Department of Anesthesiology, Duke University School of Medicine, Durham, NC
| | - Tamara M DeWinter
- Yale Tobacco Center of Regulatory Science, Department of Psychiatry, Yale School of Medicine, New Haven, CT.,Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT
| | - Melissa Mendizabal
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT
| | - Paul T Anastas
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT.,Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT.,Department of Chemistry, Yale University, New Haven, CT.,Yale School of Public Health, Yale University, New Haven, CT
| | - Sven E Jordt
- Yale Tobacco Center of Regulatory Science, Department of Psychiatry, Yale School of Medicine, New Haven, CT.,Department of Anesthesiology, Duke University School of Medicine, Durham, NC
| | - Julie B Zimmerman
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT.,Yale Tobacco Center of Regulatory Science, Department of Psychiatry, Yale School of Medicine, New Haven, CT.,Yale School of Forestry and Environmental Studies, Yale University, New Haven, CT
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14
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Gaby JM, Baker AN, Hayes JE. Vanillin modifies affective responses to but not burning sensations from ethanol in mixtures. Physiol Behav 2019; 211:112668. [PMID: 31476345 DOI: 10.1016/j.physbeh.2019.112668] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/19/2019] [Accepted: 08/30/2019] [Indexed: 12/16/2022]
Abstract
Vanillin may modulate perception of noxious oral stimuli via TRP receptor interactions; separately, vanillin has also been shown to have top-down influences on flavor perception. Here, we ask whether added vanillin decreases the perceived burn of ethanol either via peripheral or cognitive mechanisms. Participants rated the burn of ethanol with 0, 16, and 160 ppm vanillin. In studies 1 (n = 102) and 2 (n = 82), participants wore nose clips and rated the burn of 8% and 16% ethanol (study 1) or 32% and 48% ethanol (study 2). In study 3 (n = 65), participants were able to breathe freely and rated liking and perceptual qualities of 8% and 32% ethanol at each vanillin level. Vanillin showed no significant effect on ratings of burn or smoothness, but did increase perceived sweetness (p < .001) and liking (p = .004) in study 3. These data suggest vanillin does not modulate ethanol burn via TRP receptor mediated interactions, but may shift hedonic responses to ethanol via top-down processes.
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Affiliation(s)
- Jessica M Gaby
- Sensory Evaluation Center, The Pennsylvania State University, University Park, PA 16802, USA; Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Allison N Baker
- Sensory Evaluation Center, The Pennsylvania State University, University Park, PA 16802, USA; Graduate Program in Neuroscience, The Pennsylvania State University, University Park, PA 16802, USA
| | - John E Hayes
- Sensory Evaluation Center, The Pennsylvania State University, University Park, PA 16802, USA; Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
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15
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Abstract
The trigeminal sensory nerve fiber branches supply afferent information from the skin and mucous membranes of the face and head and the oral cavity regarding information on temperature, touch, and pain. Under normal conditions, the trigeminal nerve serves to provide important information from nerve fibers and tissues using specialized receptors sensitive for irritant and painful stimuli. The current scientific consensus indicates that nerve endings responsible for chemical and thermal sensitivity of the skin and mucous membranes are the same nerves responsible for nociception. This "chemesthetic sense" allows many vertebrates to detect chemical agonists that induce sensations such as touch, burning, stinging, tingling, or changes in temperature. Research has been under way for many years to determine how exposure of the oral and/or nasal cavity to compounds that elicit pungent or irritant sensations can produce these sensations. In addition, these chemicals can alter other sensory information such as taste and smell to affect the flavor of foods and beverages. We now know that these 'chemesthetic molecules' are agonists of molecular receptors, which exist on primary afferent nerve fibers that innervate the orofacial area. However, under pathophysiologic conditions, over- or underexpression or activity of these receptors may lead to painful orotrigeminal syndromes. Some of these individual receptors are discussed in detail, including transient receptor potential channels and acid sensing ion channels, among others.
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Affiliation(s)
- Amanda H Klein
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, MN, United States. //
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16
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Startek JB, Voets T, Talavera K. To flourish or perish: evolutionary TRiPs into the sensory biology of plant-herbivore interactions. Pflugers Arch 2018; 471:213-236. [PMID: 30229297 DOI: 10.1007/s00424-018-2205-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/31/2018] [Accepted: 09/06/2018] [Indexed: 12/18/2022]
Abstract
The interactions between plants and their herbivores are highly complex systems generating on one side an extraordinary diversity of plant protection mechanisms and on the other side sophisticated consumer feeding strategies. Herbivores have evolved complex, integrative sensory systems that allow them to distinguish between food sources having mere bad flavors from the actually toxic ones. These systems are based on the senses of taste, olfaction and somatosensation in the oral and nasal cavities, and on post-ingestive chemosensory mechanisms. The potential ability of plant defensive chemical traits to induce tissue damage in foragers is mainly encoded in the latter through chemesthetic sensations such as burning, pain, itch, irritation, tingling, and numbness, all of which induce innate aversive behavioral responses. Here, we discuss the involvement of transient receptor potential (TRP) channels in the chemosensory mechanisms that are at the core of complex and fascinating plant-herbivore ecological networks. We review how "sensory" TRPs are activated by a myriad of plant-derived compounds, leading to cation influx, membrane depolarization, and excitation of sensory nerve fibers of the oronasal cavities in mammals and bitter-sensing cells in insects. We also illustrate how TRP channel expression patterns and functionalities vary between species, leading to intriguing evolutionary adaptations to the specific habitats and life cycles of individual organisms.
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Affiliation(s)
- Justyna B Startek
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000, Leuven, Belgium. .,VIB Center for Brain & Disease Research, Leuven, Belgium.
| | - Thomas Voets
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000, Leuven, Belgium.,VIB Center for Brain & Disease Research, Leuven, Belgium
| | - Karel Talavera
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000, Leuven, Belgium.,VIB Center for Brain & Disease Research, Leuven, Belgium
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17
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Schwenk M. Chemical warfare agents. Classes and targets. Toxicol Lett 2017; 293:253-263. [PMID: 29197625 DOI: 10.1016/j.toxlet.2017.11.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 12/30/2022]
Abstract
Synthetic toxic chemicals (toxicants) and biological poisons (toxins) have been developed as chemical warfare agents in the last century. At the time of their initial consideration as chemical weapon, only restricted knowledge existed about their mechanisms of action. There exist two different types of acute toxic action: nonspecific cytotoxic mechanisms with multiple chemo-biological interactions versus specific mechanisms that tend to have just a single or a few target biomolecules. TRPV1- and TRPA-receptors are often involved as chemosensors that induce neurogenic inflammation. The present work briefly surveys classes and toxicologically relevant features of chemical warfare agents and describes mechanisms of toxic action.
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Affiliation(s)
- Michael Schwenk
- Formerly: Medical School Hannover. Present address: In den Kreuzäckern 16/1, 72072 Tübingen, Germany.
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18
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Beale PK, Marsh KJ, Foley WJ, Moore BD. A hot lunch for herbivores: physiological effects of elevated temperatures on mammalian feeding ecology. Biol Rev Camb Philos Soc 2017; 93:674-692. [DOI: 10.1111/brv.12364] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/25/2017] [Accepted: 08/09/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Phillipa K. Beale
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
| | - Karen J. Marsh
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
| | - William J. Foley
- Research School of Biology The Australian National University Canberra Australian Capital Territory 2601 Australia
- Animal Ecology and Conservation University of Hamburg, Martin‐Luther‐King‐Platz 3 20146 Hamburg Germany
| | - Ben D. Moore
- Hawkesbury Institute for the Environment Western Sydney University, Locked bag 1797 Penrith New South Wales 2751 Australia
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19
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Wu SW, Fowler DK, Shaffer FJ, Lindberg JEM, Peters JH. Ethyl Vanillin Activates TRPA1. J Pharmacol Exp Ther 2017; 362:368-377. [PMID: 28620120 DOI: 10.1124/jpet.116.239384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/19/2017] [Indexed: 01/11/2023] Open
Abstract
The nonselective cation channel transient receptor potential ankryn subtype family 1 (TRPA1) is expressed in neurons of dorsal root ganglia and trigeminal ganglia and also in vagal afferent neurons that innervate the lungs and gastrointestinal tract. Many TRPA1 agonists are reactive electrophilic compounds that form covalent adducts with TRPA1. Allyl isothiocyanate (AITC), the common agonist used to identify TRPA1, contains an electrophilic group that covalently binds with cysteine residues of TRPA1 and confers a structural change on the channel. There is scientific motivation to identify additional compounds that can activate TRPA1 with different mechanisms of channel gating. We provide evidence that ethyl vanillin (EVA) is a TRPA1 agonist. Using fluorescent calcium imaging and whole-cell patch-clamp electrophysiology on dissociated rat vagal afferent neurons and TRPA1-transfected COS-7 cells, we discovered that EVA activates cells also activated by AITC. Both agonists display similar current profiles and conductances. Pretreatment with A967079, a selective TRPA1 antagonist, blocks the EVA response as well as the AITC response. Furthermore, EVA does not activate vagal afferent neurons from TRPA1 knockout mice, showing selectivity for TRPA1 in this tissue. Interestingly, EVA appears to be pharmacologically different from AITC as a TRPA1 agonist. When AITC is applied before EVA, the EVA response is occluded. However, they both require intracellular oxidation to activate TRPA1. These findings suggest that EVA activates TRPA1 but via a distinct mechanism that may provide greater ease for study in native systems compared with AITC and may shed light on differential modes of TRPA1 gating by ligand types.
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Affiliation(s)
- Shaw-Wen Wu
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington (D.K.F., F.J.S., J.E.M.L., J.H.P.); and Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida (S.-w.W.)
| | - Daniel K Fowler
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington (D.K.F., F.J.S., J.E.M.L., J.H.P.); and Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida (S.-w.W.)
| | - Forrest J Shaffer
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington (D.K.F., F.J.S., J.E.M.L., J.H.P.); and Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida (S.-w.W.)
| | - Jonathon E M Lindberg
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington (D.K.F., F.J.S., J.E.M.L., J.H.P.); and Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida (S.-w.W.)
| | - James H Peters
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington (D.K.F., F.J.S., J.E.M.L., J.H.P.); and Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida (S.-w.W.)
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20
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Helional-induced activation of human olfactory receptor 2J3 promotes apoptosis and inhibits proliferation in a non-small-cell lung cancer cell line. Eur J Cell Biol 2017; 96:34-46. [DOI: 10.1016/j.ejcb.2016.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 11/10/2016] [Accepted: 11/30/2016] [Indexed: 12/20/2022] Open
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21
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Dussor G, Cao YQ. TRPM8 and Migraine. Headache 2016; 56:1406-1417. [PMID: 27634619 PMCID: PMC5335856 DOI: 10.1111/head.12948] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/31/2016] [Accepted: 06/19/2016] [Indexed: 12/27/2022]
Abstract
Migraine is among the most common diseases on earth and one of the most disabling, the latter due in large part to poor treatment efficacy. Development of new therapeutics is dependent on the identification of mechanisms contributing to migraine and discovery of targets for new drugs. Numerous genome-wide association studies (GWAS) have implicated the transient receptor-potential M8 (TRPM8) channel in migraine. This channel is predominantly expressed on peripheral sensory neurons and is known as the sensor for cold temperature in cutaneous tissue but is also expressed on deep visceral afferents where cold is not likely a stimulus. Consequently, a number of alternative endogenous agonists have been proposed. Apart from its role in cold sensation, TRPM8 also contributes to cold allodynia after nerve injury or inflammation, and it is necessary for cooling/menthol-based analgesia. How it might contribute to migraine is less clear. The purpose of this review is to discuss the anatomical and physiological mechanisms by which meningeal TRPM8 may play a role in migraine as well as the potential of TRPM8 as a therapeutic target. TRPM8 is expressed on sensory afferents innervating the meninges, and these neurons are subject to developmental changes that may influence their contribution to migraine. As in viscera, meningeal TRPM8 channels are unlikely to be activated by temperature fluctuations and their endogenous ligands remain unknown. Preclinical migraine studies show that activation of meningeal TRPM8 by exogenous agonists can both cause and alleviate headache behaviors, depending on whether other meningeal afferents concurrently receive noxious stimuli. This is reminiscent of the fact that cold can trigger migraine in humans but menthol can also alleviate headache. We propose that both TRPM8 agonists and antagonists may be potential therapeutics, depending on how migraine is triggered in individual patients. In this regard, TRPM8 may be a novel target for personalized medicine in migraine treatment.
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Affiliation(s)
- Greg Dussor
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA.
| | - Yu-Qing Cao
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
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22
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Lehmann R, Schöbel N, Hatt H, van Thriel C. The involvement of TRP channels in sensory irritation: a mechanistic approach toward a better understanding of the biological effects of local irritants. Arch Toxicol 2016; 90:1399-413. [PMID: 27037703 DOI: 10.1007/s00204-016-1703-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/24/2016] [Indexed: 01/30/2023]
Abstract
Peripheral nerves innervating the mucosae of the nose, mouth, and throat protect the organism against chemical hazards. Upon their stimulation, characteristic perceptions (e.g., stinging and burning) and various reflexes are triggered (e.g., sneezing and cough). The potency of a chemical to cause sensory irritation can be estimated by a mouse bioassay assessing the concentration-dependent decrease in the respiratory rate (50 % decrease: RD50). The involvement of the N. trigeminus and its sensory neurons in the irritant-induced decrease in respiratory rates are not well understood to date. In calcium imaging experiments, we tested which of eight different irritants (RD50 5-730 ppm) could induce responses in primary mouse trigeminal ganglion neurons. The tested irritants acetophenone, 2-ethylhexanol, hexyl isocyanate, isophorone, and trimethylcyclohexanol stimulated responses in trigeminal neurons. Most of these responses depended on functional TRPA1 or TRPV1 channels. For crotyl alcohol, 3-methyl-1-butanol, and sodium metabisulfite, no activation could be observed. 2-ethylhexanol can activate both TRPA1 and TRPV1, and at low contractions (100 µM) G protein-coupled receptors (GPCRs) seem to be involved. GPCRs might also be involved in the mediation of the responses to trimethylcyclohexanol. By using neurobiological tools, we showed that sensory irritation in vivo could be based on the direct activation of TRP channels but also on yet unknown interactions with GPCRs present in trigeminal neurons. Our results showed that the potency suggested by the RD50 values was not reflected by direct nerve-compound interaction.
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Affiliation(s)
- Ramona Lehmann
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139, Dortmund, Germany.
| | - Nicole Schöbel
- Department of Animal Physiology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Hanns Hatt
- Department of Cell Physiology, Ruhr University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Christoph van Thriel
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139, Dortmund, Germany
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23
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24
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Osterloh M, Böhm M, Kalbe B, Osterloh S, Hatt H. Identification and functional characterization of TRPA1 in human myoblasts. Pflugers Arch 2015; 468:321-33. [DOI: 10.1007/s00424-015-1729-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 08/17/2015] [Accepted: 08/19/2015] [Indexed: 10/23/2022]
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25
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Flegel C, Schöbel N, Altmüller J, Becker C, Tannapfel A, Hatt H, Gisselmann G. RNA-Seq Analysis of Human Trigeminal and Dorsal Root Ganglia with a Focus on Chemoreceptors. PLoS One 2015; 10:e0128951. [PMID: 26070209 PMCID: PMC4466559 DOI: 10.1371/journal.pone.0128951] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 05/01/2015] [Indexed: 12/11/2022] Open
Abstract
The chemosensory capacity of the somatosensory system relies on the appropriate expression of chemoreceptors, which detect chemical stimuli and transduce sensory information into cellular signals. Knowledge of the complete repertoire of the chemoreceptors expressed in human sensory ganglia is lacking. This study employed the next-generation sequencing technique (RNA-Seq) to conduct the first expression analysis of human trigeminal ganglia (TG) and dorsal root ganglia (DRG). We analyzed the data with a focus on G-protein coupled receptors (GPCRs) and ion channels, which are (potentially) involved in chemosensation by somatosensory neurons in the human TG and DRG. For years, transient receptor potential (TRP) channels have been considered the main group of receptors for chemosensation in the trigeminal system. Interestingly, we could show that sensory ganglia also express a panel of different olfactory receptors (ORs) with putative chemosensory function. To characterize OR expression in more detail, we performed microarray, semi-quantitative RT-PCR experiments, and immunohistochemical staining. Additionally, we analyzed the expression data to identify further known or putative classes of chemoreceptors in the human TG and DRG. Our results give an overview of the major classes of chemoreceptors expressed in the human TG and DRG and provide the basis for a broader understanding of the reception of chemical cues.
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Affiliation(s)
- Caroline Flegel
- Department of Cell Physiology, Ruhr-University Bochum, Bochum, Germany
| | - Nicole Schöbel
- Department of Animal Physiology, Ruhr-University Bochum, Bochum, Germany
| | | | | | | | - Hanns Hatt
- Department of Cell Physiology, Ruhr-University Bochum, Bochum, Germany
| | - Günter Gisselmann
- Department of Cell Physiology, Ruhr-University Bochum, Bochum, Germany
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26
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Valtcheva MV, Samineni VK, Golden JP, Gereau RW, Davidson S. Enhanced nonpeptidergic intraepidermal fiber density and an expanded subset of chloroquine-responsive trigeminal neurons in a mouse model of dry skin itch. THE JOURNAL OF PAIN 2015; 16:346-56. [PMID: 25640289 DOI: 10.1016/j.jpain.2015.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 01/08/2015] [Accepted: 01/16/2015] [Indexed: 12/13/2022]
Abstract
UNLABELLED Chronic pruritic conditions are often associated with dry skin and loss of epidermal barrier integrity. In this study, repeated application of acetone and ether followed by water (AEW) to the cheek skin of mice produced persistent scratching behavior with no increase in pain-related forelimb wiping, indicating the generation of itch without pain. Cheek skin immunohistochemistry showed a 64.5% increase in total epidermal innervation in AEW-treated mice compared to water-treated controls. This increase was independent of scratching, because mice prevented from scratching by Elizabethan collars showed similar hyperinnervation. To determine the effects of dry skin treatment on specific subsets of peripheral fibers, we examined Ret-positive, calcitonin gene-related peptide (CGRP)-positive, and glial cell line-derived neurotrophic factor family receptor α3 (GFRα3)-positive intraepidermal fiber density. AEW treatment increased Ret-positive fibers but not CGRP-positive or GFRα3-positive fibers, suggesting that a specific subset of nonpeptidergic fibers could contribute to dry skin itch. To test whether trigeminal ganglion neurons innervating the cheek exhibited altered excitability after AEW treatment, primary cultures of retrogradely labeled neurons were examined using whole-cell patch clamp electrophysiology. AEW treatment produced no differences in measures of excitability compared to water-treated controls. In contrast, a significantly higher proportion of trigeminal ganglion neurons was responsive to the nonhistaminergic pruritogen chloroquine after AEW treatment. We conclude that nonpeptidergic, Ret-positive fibers and chloroquine-sensitive neurons may contribute to dry skin pruritus. PERSPECTIVE This study examines the underlying neurobiological mechanisms of persistent dry skin itch. Our results indicate that nonpeptidergic epidermal hyperinnervation and nonhistaminergic pruritic receptors are potential targets for chronic pruritus.
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Affiliation(s)
- Manouela V Valtcheva
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri; Medical Scientist Training Program, Washington University in St. Louis, St. Louis, Missouri
| | - Vijay K Samineni
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Judith P Golden
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Robert W Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Steve Davidson
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri.
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27
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Abstract
![]()
To
date, 28 mammalian transient receptor potential (TRP) channels
have been cloned and characterized. They are grouped into six subfamilies
on the basis of their amino acid sequence homology: TRP Ankyrin (TRPA),
TRP Canonical (TRPC), TRP Melastatin (TRPM), TRP Mucolipin (TRPML),
TRP Polycystin (TRPP), and TRP Vanilloid (TRPV). Most of the TRP channels
are nonselective cation channels expressed on the cell membrane and
exhibit variable permeability ratios for Ca2+ versus Na+. They mediate sensory functions (such as vision, nociception,
taste transduction, temperature sensation, and pheromone signaling)
and homeostatic functions (such as divalent cation flux, hormone release,
and osmoregulation). Significant progress has been made in our understanding
of the specific roles of these TRP channels and their activation mechanisms.
In this Review, the emphasis will be on the activation of TRP channels
by phytochemicals that are claimed to exert health benefits. Recent
findings complement the anecdotal evidence that some of these phytochemicals
have specific receptors and the activation of which is responsible
for the physiological effects. Now, the targets for these phytochemicals
are being unveiled; a specific hypothesis can be proposed and tested
experimentally to infer a scientific validity of the claims of the
health benefits. The broader and pressing issues that have to be addressed
are related to the quantities of the active ingredients in a given
preparation, their bioavailability, metabolism, adverse effects, excretion,
and systemic versus local effects.
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Affiliation(s)
- Louis S. Premkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702, United States
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28
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Dussor G, Yan J, Xie JY, Ossipov MH, Dodick DW, Porreca F. Targeting TRP channels for novel migraine therapeutics. ACS Chem Neurosci 2014; 5:1085-96. [PMID: 25138211 PMCID: PMC4240253 DOI: 10.1021/cn500083e] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
![]()
Migraine is increasingly understood
to be a disorder of the brain.
In susceptible individuals, a variety of “triggers”
may influence altered central excitability, resulting in the activation
and sensitization of trigeminal nociceptive afferents surrounding
blood vessels (i.e., the trigeminovascular system), leading to migraine
pain. Transient receptor potential (TRP) channels are expressed in
a subset of dural afferents, including those containing calcitonin
gene related peptide (CGRP). Activation of TRP channels promotes excitation
of nociceptive afferent fibers and potentially lead to pain. In addition
to pain, allodynia to mechanical and cold stimuli can result from
sensitization of both peripheral afferents and of central pain pathways.
TRP channels respond to a variety of endogenous conditions including
chemical mediators and low pH. These channels can be activated by
exogenous stimuli including a wide range of chemical and environmental
irritants, some of which have been demonstrated to trigger migraine
in humans. Activation of TRP channels can elicit CGRP release, and
blocking the effects of CGRP through receptor antagonism or antibody
strategies has been demonstrated to be effective in the treatment
of migraine. Identification of approaches that can prevent activation
of TRP channels provides an additional novel strategy for discovery
of migraine therapeutics.
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Affiliation(s)
- Gregory Dussor
- School
of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, United States
| | - J. Yan
- Department
of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - Jennifer Y. Xie
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
| | - Michael H. Ossipov
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
| | - David W. Dodick
- Department
of Neurology, Mayo Clinic Arizona, Phoenix, Arizona 85054, United States
| | - Frank Porreca
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
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29
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Ortar G, Schiano Moriello A, Morera E, Nalli M, Di Marzo V, De Petrocellis L. Effect of acyclic monoterpene alcohols and their derivatives on TRP channels. Bioorg Med Chem Lett 2014; 24:5507-11. [PMID: 25455494 DOI: 10.1016/j.bmcl.2014.10.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 10/24/2022]
Abstract
A series of thirty-six geraniol, nerol, citronellol, geranylamine, and nerylamine derivatives was synthesized and tested on TRPA1, TRPM8, and TRPV1 channels. Most of them acted as strong modulators of TRPA1 channels with EC50 and/or IC50 values <1 μM. None was able to significantly activate TRPM8 channels, while thirteen of them behaved as 'true' TRPM8 antagonists. Little or no effect was generally observed on TRPV1 channels. Some of the compounds examined, that is, compounds 1d,g,n, 2c,d,h,i,o, 3b,e exhibited an appreciable selectivity for TRPA1 subtype.
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Affiliation(s)
- Giorgio Ortar
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, piazzale Aldo Moro 5, 00185 Roma, Italy.
| | - Aniello Schiano Moriello
- Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, via dei Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy
| | - Enrico Morera
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Marianna Nalli
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, via dei Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy
| | - Luciano De Petrocellis
- Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, via dei Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy.
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