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Socała K, Jakubiec M, Abram M, Mlost J, Starowicz K, Kamiński RM, Ciepiela K, Andres-Mach M, Zagaja M, Metcalf CS, Zawadzki P, Wlaź P, Kamiński K. TRPV1 channel in the pathophysiology of epilepsy and its potential as a molecular target for the development of new antiseizure drug candidates. Prog Neurobiol 2024; 240:102634. [PMID: 38834133 DOI: 10.1016/j.pneurobio.2024.102634] [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: 10/25/2023] [Revised: 04/26/2024] [Accepted: 05/28/2024] [Indexed: 06/06/2024]
Abstract
Identification of transient receptor potential cation channel, subfamily V member 1 (TRPV1), also known as capsaicin receptor, in 1997 was a milestone achievement in the research on temperature sensation and pain signalling. Very soon after it became evident that TRPV1 is implicated in a wide array of physiological processes in different peripheral tissues, as well as in the central nervous system, and thereby could be involved in the pathophysiology of numerous diseases. Increasing evidence suggests that modulation of TRPV1 may also affect seizure susceptibility and epilepsy. This channel is localized in brain regions associated with seizures and epilepsy, and its overexpression was found both in animal models of seizures and in brain samples from epileptic patients. Moreover, modulation of TRPV1 on non-neuronal cells (microglia, astrocytes, and/or peripheral immune cells) may have an impact on the neuroinflammatory processes that play a role in epilepsy and epileptogenesis. In this paper, we provide a comprehensive and critical overview of currently available data on TRPV1 as a possible molecular target for epilepsy management, trying to identify research gaps and future directions. Overall, several converging lines of evidence implicate TRPV1 channel as a potentially attractive target in epilepsy research but more studies are needed to exploit the possible role of TRPV1 in seizures/epilepsy and to evaluate the value of TRPV1 ligands as candidates for new antiseizure drugs.
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Affiliation(s)
- Katarzyna Socała
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, Lublin PL 20-033, Poland.
| | - Marcin Jakubiec
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland
| | - Michał Abram
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland
| | - Jakub Mlost
- Department of Neurochemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, Cracow PL 31-343, Poland
| | - Katarzyna Starowicz
- Department of Neurochemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, Cracow PL 31-343, Poland
| | - Rafał M Kamiński
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland
| | - Katarzyna Ciepiela
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland; Selvita S.A., Bobrzyńskiego 14, Cracow PL 30-348, Poland
| | - Marta Andres-Mach
- Department of Experimental Pharmacology, Institute of Rural Health, Jaczewskiego 2, Lublin PL 20-090, Poland
| | - Mirosław Zagaja
- Department of Experimental Pharmacology, Institute of Rural Health, Jaczewskiego 2, Lublin PL 20-090, Poland
| | - Cameron S Metcalf
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA
| | - Przemysław Zawadzki
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland
| | - Piotr Wlaź
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, Lublin PL 20-033, Poland
| | - Krzysztof Kamiński
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Cracow PL 30-688, Poland
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Huffer K, Oskoui EV, Swartz KJ. Conservation of the cooling agent binding pocket within the TRPM subfamily. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595003. [PMID: 38826484 PMCID: PMC11142142 DOI: 10.1101/2024.05.20.595003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Transient Receptor Potential (TRP) channels are a large and diverse family of tetrameric cation selective channels that are activated by many different types of stimuli, including noxious heat or cold, organic ligands such as vanilloids or cooling agents, or intracellular Ca2+. Structures available for all subtypes of TRP channels reveal that the transmembrane domains are closely related despite their unique sensitivity to activating stimuli. Here we use computational and electrophysiological approaches to explore the conservation of the cooling agent binding pocket identified within the S1-S4 domain of the Melastatin subfamily member TRPM8, the mammalian sensor of noxious cold, with other TRPM channel subtypes. We find that a subset of TRPM channels, including TRPM2, TRPM4 and TRPM5, contain well-conserved cooling agent binding pockets. We then show how the cooling agent icilin modulates activation of TRPM4 to intracellular Ca2+, enhancing the sensitivity of the channel to Ca2+ and diminishing outward-rectification to promote opening at negative voltages. Mutations known to promote or diminish activation of TRPM8 by icilin similarly alter activation of TRPM4 by the cooling agent, suggesting that icilin binds to the cooling agent binding pocket to promote opening of the channel. These findings demonstrate that TRPM4 and TRPM8 channels share related cooling agent binding pockets that are allosterically coupled to opening of the pore.
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Affiliation(s)
- Kate Huffer
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | | | - Kenton J. Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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Cherry AL, Wheeler MJ, Mathisova K, Di Miceli M. In silico analyses of the involvement of GPR55, CB1R and TRPV1: response to THC, contribution to temporal lobe epilepsy, structural modeling and updated evolution. Front Neuroinform 2024; 18:1294939. [PMID: 38404644 PMCID: PMC10894036 DOI: 10.3389/fninf.2024.1294939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 01/19/2024] [Indexed: 02/27/2024] Open
Abstract
Introduction The endocannabinoid (eCB) system is named after the discovery that endogenous cannabinoids bind to the same receptors as the phytochemical compounds found in Cannabis. While endogenous cannabinoids include anandamide (AEA) and 2-arachidonoylglycerol (2-AG), exogenous phytocannabinoids include Δ-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). These compounds finely tune neurotransmission following synapse activation, via retrograde signaling that activates cannabinoid receptor 1 (CB1R) and/or transient receptor potential cation channel subfamily V member 1 (TRPV1). Recently, the eCB system has been linked to several neurological diseases, such as neuro-ocular abnormalities, pain insensitivity, migraine, epilepsy, addiction and neurodevelopmental disorders. In the current study, we aim to: (i) highlight a potential link between the eCB system and neurological disorders, (ii) assess if THC exposure alters the expression of eCB-related genes, and (iii) identify evolutionary-conserved residues in CB1R or TRPV1 in light of their function. Methods To address this, we used several bioinformatic approaches, such as transcriptomic (Gene Expression Omnibus), protein-protein (STRING), phylogenic (BLASTP, MEGA) and structural (Phyre2, AutoDock, Vina, PyMol) analyzes. Results Using RNA sequencing datasets, we did not observe any dysregulation of eCB-related transcripts in major depressive disorders, bipolar disorder or schizophrenia in the anterior cingulate cortex, nucleus accumbens or dorsolateral striatum. Following in vivo THC exposure in adolescent mice, GPR55 was significantly upregulated in neurons from the ventral tegmental area, while other transcripts involved in the eCB system were not affected by THC exposure. Our results also suggest that THC likely induces neuroinflammation following in vitro application on mice microglia. Significant downregulation of TPRV1 occurred in the hippocampi of mice in which a model of temporal lobe epilepsy was induced, confirming previous observations. In addition, several transcriptomic dysregulations were observed in neurons of both epileptic mice and humans, which included transcripts involved in neuronal death. When scanning known interactions for transcripts involved in the eCB system (n = 12), we observed branching between the eCB system and neurophysiology, including proteins involved in the dopaminergic system. Our protein phylogenic analyzes revealed that CB1R forms a clade with CB2R, which is distinct from related paralogues such as sphingosine-1-phosphate, receptors, lysophosphatidic acid receptors and melanocortin receptors. As expected, several conserved residues were identified, which are crucial for CB1R receptor function. The anandamide-binding pocket seems to have appeared later in evolution. Similar results were observed for TRPV1, with conserved residues involved in receptor activation. Conclusion The current study found that GPR55 is upregulated in neurons following THC exposure, while TRPV1 is downregulated in temporal lobe epilepsy. Caution is advised when interpreting the present results, as we have employed secondary analyzes. Common ancestors for CB1R and TRPV1 diverged from jawless vertebrates during the late Ordovician, 450 million years ago. Conserved residues are identified, which mediate crucial receptor functions.
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Affiliation(s)
- Amy L. Cherry
- Worcester Biomedical Research Group, School of Science and the Environment, University of Worcester, Worcester, United Kingdom
| | - Michael J. Wheeler
- Sustainable Environments Research Group, School of Science and the Environment University of Worcester, Worcester, United Kingdom
| | - Karolina Mathisova
- School of Science and the Environment University of Worcester, Worcester, United Kingdom
| | - Mathieu Di Miceli
- Worcester Biomedical Research Group, School of Science and the Environment, University of Worcester, Worcester, United Kingdom
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Oz M, Lorke DE, Howarth FC. Transient receptor potential vanilloid 1 (TRPV1)-independent actions of capsaicin on cellular excitability and ion transport. Med Res Rev 2023. [PMID: 36916676 DOI: 10.1002/med.21945] [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: 06/14/2022] [Revised: 01/17/2023] [Accepted: 02/26/2023] [Indexed: 03/15/2023]
Abstract
Capsaicin is a naturally occurring alkaloid derived from chili pepper that is responsible for its hot pungent taste. Capsaicin is known to exert multiple pharmacological actions, including analgesia, anticancer, anti-inflammatory, antiobesity, and antioxidant effects. The transient receptor potential vanilloid subfamily member 1 (TRPV1) is the main receptor mediating the majority of the capsaicin effects. However, numerous studies suggest that the TRPV1 receptor is not the only target for capsaicin. An increasing number of studies indicates that capsaicin, at low to mid µM ranges, not only indirectly through TRPV1-mediated Ca2+ increases, but also directly modulates the functions of voltage-gated Na+ , K+ , and Ca2+ channels, as well as ligand-gated ion channels and other ion transporters and enzymes involved in cellular excitability. These TRPV1-independent effects are mediated by alterations of the biophysical properties of the lipid membrane and subsequent modulation of the functional properties of ion channels and by direct binding of capsaicin to the channels. The present study, for the first time, systematically categorizes this diverse range of non-TRPV1 targets and discusses cellular and molecular mechanisms mediating TRPV1-independent effects of capsaicin in excitable, as well as nonexcitable cells.
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Affiliation(s)
- Murat Oz
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Kuwait University, Safat, Kuwait
| | - Dietrich E Lorke
- Department of Anatomy and Cellular Biology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates.,Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Frank C Howarth
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates
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Kawabata R, Shimoyama S, Ueno S, Yao I, Arata A, Koga K. TRPA1 as a O 2 sensor detects microenvironmental hypoxia in the mice anterior cingulate cortex. Sci Rep 2023; 13:2960. [PMID: 36807332 PMCID: PMC9941080 DOI: 10.1038/s41598-023-29140-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 01/31/2023] [Indexed: 02/22/2023] Open
Abstract
Transient receptor potential ankyrin 1 (TRPA1) is a member of the TRP channel family and is expressed in peripheral and central nervous systems. In the periphery, TRPA1 senses cold and pain. However, the functions of TRPA1 in the CNS are unclear. Here, we examined the roles of TRPA1 on neural activity and synaptic transmission in layer II/III pyramidal neurons from mice anterior cingulate cortex (ACC) by whole-cell patch-clamp recordings. The activation of Cinnamaldehyde (CA), which is TRPA1 agonist produced inward currents and these were blocked by the TRPA1 antagonists. Furthermore, activating TRPA1 changed the properties of action potentials such as the firing rate, rise time and decay time. In contrast, stimulating TRPA1 did not alter the spontaneous synaptic transmission. Finally, we examined the functional role of TRPA1 on neurons in a hypoxic environment. We induced an acute hypoxia by substituting nitrogen (N2) gas for oxygen (O2) in the external solution. N2 produced biphasic effects that consisting of inward currents in the early phase and outward currents in the late phase. Importantly, blocking TRPA1 reduced inward currents, but not outward currents. In contrast, a KATP channel blocker completely inhibited outward currents. These results suggest that TRPA1 acts on postsynaptic neurons in the ACC as an acute O2 sensor.
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Affiliation(s)
- Ryo Kawabata
- grid.258777.80000 0001 2295 9421Department of Biomedical Chemistry major, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo Japan ,grid.272264.70000 0000 9142 153XDepartment of Neurophysiology, Hyogo Medical University, Nishinomiya, Hyogo Japan
| | - Shuji Shimoyama
- grid.257016.70000 0001 0673 6172Department of Neurophysiology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori Japan
| | - Shinya Ueno
- grid.257016.70000 0001 0673 6172Department of Neurophysiology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori Japan
| | - Ikuko Yao
- grid.258777.80000 0001 2295 9421Department of Biomedical Chemistry major, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo Japan
| | - Akiko Arata
- Department of Physiology, Hyogo Medical University, Nishinomiya, Hyogo, Japan.
| | - Kohei Koga
- Department of Neurophysiology, Hyogo Medical University, Nishinomiya, Hyogo, Japan.
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Choudhary N, Tewari D, Nabavi SF, Kashani HRK, Lorigooini Z, Filosa R, Khan FB, Masoudian N, Nabavi SM. Plant based food bioactives: A boon or bane for neurological disorders. Crit Rev Food Sci Nutr 2022; 64:3279-3325. [PMID: 36369694 DOI: 10.1080/10408398.2022.2131729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.
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Affiliation(s)
- Neeraj Choudhary
- Department of Pharmacognosy, Adesh Institute of Pharmacy and Biomedical Sciences, Adesh University, Bathinda, Punjab, India
| | - Devesh Tewari
- Department of Pharmacognosy and Phytochemistry, School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi, India
| | - Seyed Fazel Nabavi
- Advanced Medical Pharma (AMP-Biotec), Biopharmaceutical Innovation Centre Via Cortenocera, 82030, San Salvatore Telesino, (BN), Italy
- Nutringredientes Research Center, Federal Institute of Education, Science and Technology (IFCE), Baturite, Ceara, Brazil
| | - Hamid Reza Khayat Kashani
- Department of Neurosurgery, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zahra Lorigooini
- Medical Plants Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Rosanna Filosa
- Advanced Medical Pharma (AMP-Biotec), Biopharmaceutical Innovation Centre Via Cortenocera, 82030, San Salvatore Telesino, (BN), Italy
- Department of Science and Technology, University of Sannio, 82100, Benevento, Italy
| | - Farheen Badrealam Khan
- Department of Biology, College of Science, The United Arab Emirates University, Al Ain, 15551 United Arab Emirates
| | - Nooshin Masoudian
- Advanced Medical Pharma (AMP-Biotec), Biopharmaceutical Innovation Centre Via Cortenocera, 82030, San Salvatore Telesino, (BN), Italy
| | - Seyed Mohammad Nabavi
- Advanced Medical Pharma (AMP-Biotec), Biopharmaceutical Innovation Centre Via Cortenocera, 82030, San Salvatore Telesino, (BN), Italy
- Nutringredientes Research Center, Federal Institute of Education, Science and Technology (IFCE), Baturite, Ceara, Brazil
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Li Z, Zhang H, Wang Y, Li Y, Li Q, Zhang L. The distinctive role of menthol in pain and analgesia: Mechanisms, practices, and advances. Front Mol Neurosci 2022; 15:1006908. [PMID: 36277488 PMCID: PMC9580369 DOI: 10.3389/fnmol.2022.1006908] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Menthol is an important flavoring additive that triggers a cooling sensation. Under physiological condition, low to moderate concentrations of menthol activate transient receptor potential cation channel subfamily M member 8 (TRPM8) in the primary nociceptors, such as dorsal root ganglion (DRG) and trigeminal ganglion, generating a cooling sensation, whereas menthol at higher concentration could induce cold allodynia, and cold hyperalgesia mediated by TRPM8 sensitization. In addition, the paradoxical irritating properties of high concentrations of menthol is associated with its activation of transient receptor potential cation channel subfamily A member 1 (TRPA1). Under pathological situation, menthol activates TRPM8 to attenuate mechanical allodynia and thermal hyperalgesia following nerve injury or chemical stimuli. Recent reports have recapitulated the requirement of central group II/III metabotropic glutamate receptors (mGluR) with endogenous κ-opioid signaling pathways for menthol analgesia. Additionally, blockage of sodium channels and calcium influx is a determinant step after menthol exposure, suggesting the possibility of menthol for pain management. In this review, we will also discuss and summarize the advances in menthol-related drugs for pathological pain treatment in clinical trials, especially in neuropathic pain, musculoskeletal pain, cancer pain and postoperative pain, with the aim to find the promising therapeutic candidates for the resolution of pain to better manage patients with pain in clinics.
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Affiliation(s)
- Ziping Li
- The Graduate School, Tianjin Medical University, Tianjin, China
| | - Haoyue Zhang
- The Graduate School, Tianjin Medical University, Tianjin, China
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yigang Wang
- The Graduate School, Tianjin Medical University, Tianjin, China
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yize Li
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Qing Li
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
- Qing Li,
| | - Linlin Zhang
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
- *Correspondence: Linlin Zhang,
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Beneficial Effects of Capsaicin in Disorders of the Central Nervous System. Molecules 2022; 27:molecules27082484. [PMID: 35458680 PMCID: PMC9029810 DOI: 10.3390/molecules27082484] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/01/2022] [Accepted: 04/07/2022] [Indexed: 01/13/2023] Open
Abstract
Capsaicin is a natural compound found in chili peppers and is used in the diet of many countries. The important mechanism of action of capsaicin is its influence on TRPV1 channels in nociceptive sensory neurons. Furthermore, the beneficial effects of capsaicin in cardiovascular and oncological disorders have been described. Many recent publications show the positive effects of capsaicin in animal models of brain disorders. In Alzheimer’s disease, capsaicin reduces neurodegeneration and memory impairment. The beneficial effects of capsaicin in Parkinson’s disease and depression have also been described. It has been found that capsaicin reduces the area of infarction and improves neurological outcomes in animal models of stroke. However, both proepileptic and antiepileptic effects of capsaicin in animal models of epilepsy have been proposed. These contradictory results may be caused by the fact that capsaicin influences not only TRPV1 channels but also different molecular targets such as voltage-gated sodium channels. Human studies show that capsaicin may be helpful in treating stroke complications such as dysphagia. Additionally, this compound exerts pain-relieving effects in migraine and cluster headaches. The purpose of this review is to discuss the mechanisms of the beneficial effects of capsaicin in disorders of the central nervous system.
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Tyagi S, Shekhar N, Thakur AK. Protective Role of Capsaicin in Neurological Disorders: An Overview. Neurochem Res 2022; 47:1513-1531. [PMID: 35150419 DOI: 10.1007/s11064-022-03549-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 11/24/2022]
Abstract
Different pathological conditions that begin with slow and progressive deformations, cause irreversible affliction by producing loss of neurons and synapses. Commonly it is referred to as 'protein misfolding' diseases or proteinopathies and comprises the latest definition of neurological disorders (ND). Protein misfolding dynamics, proteasomal dysfunction, aggregation, defective degradation, oxidative stress, free radical formation, mitochondrial dysfunctions, impaired bioenergetics, DNA damage, neuronal Golgi apparatus fragmentation, axonal transport disruption, Neurotrophins (NTFs) dysfunction, neuroinflammatory or neuroimmune processes, and neurohumoral changes are the several mechanisms that embark the pathogenesis of ND. Capsaicin (8-Methyl-N-vanillyl-6-nonenamide) one of the major phenolic components in chili peppers (Capsicum) distinctively triggers the unmyelinated C-fiber and acts on Transient Receptor Potential Vanilloid-1, which is a Ca2+ permeable, non-selective cation channel. Several studies have shown the neuroprotective role of capsaicin against oxidative damage, behavioral impairment, with 6-hydroxydopamine (6-OHDA) induced Parkinson's disease, pentylenetetrazol-induced seizures, global cerebral ischemia, and streptozotocin-induced Alzheimer's disease. Based on these lines of evidence, capsaicin can be considered as a potential constituent to develop suitable neuro-pharmacotherapeutics for the management and treatment of ND. Furthermore, exploring newer horizons and carrying out proper clinical trials would help to bring out the promising effects of capsaicin to be recommended as a neuroprotectant.
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Affiliation(s)
- Sakshi Tyagi
- Neuropharmacology Research Laboratory, School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi, 110 017, India
| | - Nikhila Shekhar
- Neuropharmacology Research Laboratory, School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi, 110 017, India
| | - Ajit Kumar Thakur
- Neuropharmacology Research Laboratory, School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi, 110 017, India.
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10
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Menthol exerts TRPM8-independent antiepileptic effects in prefrontal cortex pyramidal neurons. Brain Res 2022; 1783:147847. [DOI: 10.1016/j.brainres.2022.147847] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 02/03/2022] [Accepted: 02/23/2022] [Indexed: 11/22/2022]
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Sauna-like conditions or menthol treatment reduce tau phosphorylation through mild hyperthermia. Neurobiol Aging 2022; 113:118-130. [DOI: 10.1016/j.neurobiolaging.2022.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 02/02/2022] [Accepted: 02/20/2022] [Indexed: 02/08/2023]
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12
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Tournissac M, Leclerc M, Valentin-Escalera J, Vandal M, Bosoi CR, Planel E, Calon F. Metabolic determinants of Alzheimer's disease: A focus on thermoregulation. Ageing Res Rev 2021; 72:101462. [PMID: 34534683 DOI: 10.1016/j.arr.2021.101462] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/09/2021] [Accepted: 09/11/2021] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is a complex age-related neurodegenerative disease, associated with central and peripheral metabolic anomalies, such as impaired glucose utilization and insulin resistance. These observations led to a considerable interest not only in lifestyle-related interventions, but also in repurposing insulin and other anti-diabetic drugs to prevent or treat dementia. Body temperature is the oldest known metabolic readout and mechanisms underlying its maintenance fail in the elderly, when the incidence of AD rises. This raises the possibility that an age-associated thermoregulatory deficit contributes to energy failure underlying AD pathogenesis. Brown adipose tissue (BAT) plays a central role in thermogenesis and maintenance of body temperature. In recent years, the modulation of BAT activity has been increasingly demonstrated to regulate energy expenditure, insulin sensitivity and glucose utilization, which could also provide benefits for AD. Here, we review the evidence linking thermoregulation, BAT and insulin-related metabolic defects with AD, and we propose mechanisms through which correcting thermoregulatory impairments could slow the progression and delay the onset of AD.
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Moriyama H, Nomura S, Imoto H, Inoue T, Fujiyama Y, Haji K, Maruta Y, Ishihara H, Suzuki M. Suppressive Effects of Transient Receptor Potential Melastatin 8 Agonist on Epileptiform Discharges and Epileptic Seizures. Front Pharmacol 2021; 12:766782. [PMID: 34658898 PMCID: PMC8517222 DOI: 10.3389/fphar.2021.766782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 09/16/2021] [Indexed: 01/12/2023] Open
Abstract
Epilepsy is a relatively common condition, but more than 30% of patients have refractory epilepsy that is inadequately controlled by or is resistant to multiple drug treatments. Thus, new antiepileptic drugs based on newly identified mechanisms are required. A previous report revealed the suppressive effects of transient receptor potential melastatin 8 (TRPM8) activation on penicillin G-induced epileptiform discharges (EDs). However, it is unclear whether TRPM8 agonists suppress epileptic seizures or affect EDs or epileptic seizures in TRPM8 knockout (TRPM8KO) mice. We investigated the effects of TRPM8 agonist and lack of TRPM8 channels on EDs and epileptic seizures. Mice were injected with TRPM8 agonist 90 min after or 30 min before epilepsy-inducer injection, and electrocorticograms (ECoGs) were recorded under anesthesia, while behavior was monitored when awake. TRPM8 agonist suppressed EDs and epileptic seizures in wildtype (WT) mice, but not in TRPM8KO mice. In addition, TRPM8KO mice had a shorter firing latency of EDs, and EDs and epileptic seizures were deteriorated by the epilepsy inducer compared with those in WT mice, with the EDs being more easily propagated to the contralateral side. These findings suggest that TRPM8 activation in epileptic regions has anti-epileptic effects.
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Affiliation(s)
- Hiroshi Moriyama
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Sadahiro Nomura
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan.,Epilepsy Center, Yamaguchi University Hospital, Ube, Japan
| | - Hirochika Imoto
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan.,Epilepsy Center, Yamaguchi University Hospital, Ube, Japan
| | - Takao Inoue
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Yuichi Fujiyama
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Kohei Haji
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Yuichi Maruta
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Hideyuki Ishihara
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
| | - Michiyasu Suzuki
- Departments of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Ube, Japan
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Wang G. Ligand-stereoselective allosteric activation of cold-sensing TRPM8 channels by an H-bonded homochiral menthol dimer with head-to-head or head-to-tail. Chirality 2021; 33:783-796. [PMID: 34596287 DOI: 10.1002/chir.23364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 11/07/2022]
Abstract
Both menthol and its analog WS-12 share the same hydrophobic intra-subunit binding pocket between a voltage-sensor-like domain and a TRP domain in a cold-sensing TRPM8 channel. However, unlike WS-12, menthol upregulates TRPM8 with a low efficacy but a high coefficient of a dose response at membrane hyperpolarization and with ligand stereoselectivity at membrane depolarization. The underlying mechanisms are unknown. Here, this in silico research suggested that the ligand-stereoselective sequential cooperativity between two menthol molecules in the WS-12 pocket is required for allosteric activation of TRPM8. Furthermore, two H-bonded homochiral menthol dimers with both head-to-head and head-to-tail can compete for the WS-12 site via non-covalent interactions. Although both dimers can form an H-bonding network with a voltage sensor S4 to disrupt a S3-S4 salt bridge in the voltage-sensor-like domain to release a "parking brake," only one dimer may drive channel opening by pushing a "gas pedal" in the TRP domain away from the S6 gate against S4. In this way, the efficacy is decreased, but the cooperativity is increased for the menthol effect at membrane hyperpolarization. Therefore, this review may extend a new pathway for ligand-stereoselective allosteric regulation of other voltage- and ligand-gated ion channels by menthol.
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Affiliation(s)
- Guangyu Wang
- Department of Drug Research and Development, Institute of Biophysical Medico-chemistry, Reno, NV, USA
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15
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Barbas LAL, Torres MF, da Costa BMPA, Feitosa MJM, Maltez LC, Amado LL, Toda YPS, Batista PDS, Cabral DAC, Hamoy M. Eugenol induces body immobilization yet evoking an increased neuronal excitability in fish during short-term baths. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 231:105734. [PMID: 33385846 DOI: 10.1016/j.aquatox.2020.105734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 11/25/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Several studies have suggested eugenol as a suitable anaesthetic for fish. However, it has also been regarded as a toxic and aversive substance to several aquatic organisms, including fish. This study sought to assess the eugenol-induced behavioural alterations and its seizurogenic potential to fish. Moreover, a distinctive methodology for an in vivo evaluation of the brain activity was also presented. Prior to the evaluation of eugenol-induced responses, fish were exposed to pentylenetetrazole (PTZ), to characterize any seizure-like patterns. Antagonizing responses to PTZ were assessed in fish receiving diazepam (BDZ) and subsequently exposed to PTZ. Tambaqui fish juveniles, Colossoma macropomum (15.8 ± 2.8 g) were used as models and assayed as follows: (i) fish exposed to PTZ (15 mM) and (ii) fish receiving a dose of BDZ (10 mg Kg-1) and later exposed to PTZ (15 mM) (BDZ-PTZ group). Thereafter, fish were evaluated throughout (iii) eugenol exposure at 65 μL L-1 (ethanolic solution) and recovery. Control fish and a vehicle control group (ethanol at 585 μL L-1) were also established. PTZ baths elicited body immobilization preceded by hyperactivity in a stereotyped seizure-like behaviour with increased EEG wave amplitude and frequency. PTZ effects in the brain were attenuated by a pre-administration of BDZ. Upon eugenol exposure, tambaqui had an intense neuronal excitability, showing a clonus-like seizure behaviour, also corroborated by the EEG patterns, which were consistent with a seizure-like response. Responses of eugenol-exposed fish resembled those of the PZT-exposed animals, with epileptiform discharges. EMG was in line with the EEG modulation, showing increased tracing oscillations and higher mean amplitudes in PTZ-exposed fish whereas in BDZ-PTZ group muscle contraction was less frequent and powerful. Fish exposed to eugenol showed initially some muscle activity followed by a loss of muscle tonus over time. In summary, our results showed that upon eugenol exposure, although a time-dependent body immobilization was attained, fish presented an intense neuronal excitability comparable to that evoked by PTZ. Eugenol failed to promote depression of the CNS and therefore may be not suitable to be used for general anaesthesia of C. macropomum. As eugenol could be implicated in seizurogenesis and be potentially toxic to the fish brain, protocols suggesting the broad use of eugenol for short-term anaesthesia or euthanasia of fish should be carefully revised, as it raises important concerns in terms of ethics and fish welfare.
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Affiliation(s)
- Luis André L Barbas
- Laboratório de Aquacultura de Espécies Tropicais (LAET), Instituto Federal de Educação Ciência e Tecnologia do Pará (IFPA), Castanhal, PA, Brazil.
| | - Marcelo Ferreira Torres
- Laboratório de Aquacultura de Espécies Tropicais (LAET), Instituto Federal de Educação Ciência e Tecnologia do Pará (IFPA), Castanhal, PA, Brazil
| | - Brenda Maria P A da Costa
- Laboratório de Aquacultura de Espécies Tropicais (LAET), Instituto Federal de Educação Ciência e Tecnologia do Pará (IFPA), Castanhal, PA, Brazil
| | - Maria Jhenneff Máximo Feitosa
- Laboratório de Aquacultura de Espécies Tropicais (LAET), Instituto Federal de Educação Ciência e Tecnologia do Pará (IFPA), Castanhal, PA, Brazil
| | - Lucas Campos Maltez
- Laboratório de Piscicultura Estuarina e Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brazil
| | - Lílian Lund Amado
- Laboratório de Ecotoxicologia (ICB) e Laboratório de Pesquisas em Monitoramento Ambiental Marinho (LAPMAR), Universidade Federal do Pará (UFPA), Belém, PA, Brazil
| | - Ywa Perpetuo Socorro Toda
- Laboratório de Farmacologia e Toxicologia de Produtos Naturais, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Belém, PA, Brazil
| | - Paula Dos Santos Batista
- Laboratório de Farmacologia e Toxicologia de Produtos Naturais, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Belém, PA, Brazil
| | - Diego Arthur Castro Cabral
- Laboratório de Farmacologia e Toxicologia de Produtos Naturais, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Belém, PA, Brazil
| | - Moisés Hamoy
- Laboratório de Farmacologia e Toxicologia de Produtos Naturais, Instituto de Ciências Biológicas, Universidade Federal do Pará (UFPA), Belém, PA, Brazil.
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Barot J, Saxena B. Therapeutic effects of eugenol in a rat model of traumatic brain injury: A behavioral, biochemical, and histological study. J Tradit Complement Med 2021; 11:318-327. [PMID: 34195026 PMCID: PMC8240337 DOI: 10.1016/j.jtcme.2021.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 01/05/2021] [Accepted: 01/05/2021] [Indexed: 12/02/2022] Open
Abstract
Background and aim Traumatic brain injury (TBI) results in death or long term functional disabilities. Eugenol is demonstrated to be beneficial in a range of experimental models of neurological disorders via its anti-inflammatory and antioxidant properties. Thus, the present study was designed to investigate the neuroprotective effects of eugenol in a weight-drop induced rat model of TBI. Experimental procedure Rats were assigned into five groups; control and TBI groups pretreated with vehicle, and three TBI groups pretreated with different doses of eugenol (25, 50, and 100 mg/kg/day, p.o., seven consecutive days). Except for the control, all other groups were subjected to TBI using Marmarou’s weight-drop method. 24 h after TBI, locomotor functions and short term memory were evaluated. Lastly animals were scarified and the estimation of lipid peroxidation in brain tissue, blood-brain barrier (BBB) integrity, brain water content (brain edema) and histopathology of the brain tissue were performed. Results Weight-drop induced TBI caused functional disabilities in the rats as indicated by impairment in locomotor activities and short term memory. The TBI also resulted in augmented neuronal cell death designated by chromatolysis. The results also showed disruption in the BBB integrity, increased edema, and lipid peroxidation in the brain of the rats exposed to trauma. Pretreatment with eugenol (100 mg/kg) ameliorated histopathological, neurochemical, and behavioral consequences of trauma. Conclusion For the first time this study revealed that eugenol can be considered as a potential candidate for managing the functional disabilities associated with TBI because of its antioxidant activities. Eugenol pretreatment ameliorated the TBI induced disruption in the BBB integrity and increased brain edema in the rats. Eugenol pretreatment in rats mitigated the TBI induced increase in lipid peroxidation and chromatolysis. Eugenol pretreatment in rats reduced the TBI induced impairment in memory, locomotor activity, and motor coordination.
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Affiliation(s)
- Jeetprakash Barot
- Department of Pharmacology, Institute of Pharmacy, Nirma University, S.G. Highway, Ahmedabad, 382481, India
| | - Bhagawati Saxena
- Department of Pharmacology, Institute of Pharmacy, Nirma University, S.G. Highway, Ahmedabad, 382481, India
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Pasierski M, Szulczyk B. Capsaicin inhibits sodium currents and epileptiform activity in prefrontal cortex pyramidal neurons. Neurochem Int 2020; 135:104709. [PMID: 32105721 DOI: 10.1016/j.neuint.2020.104709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/31/2020] [Accepted: 02/20/2020] [Indexed: 11/19/2022]
Abstract
Capsaicin, a compound found in chili peppers, causes burning sensations by acting on the peripheral sensory system. However, it has also been reported to exert substantial effects on central neurons. The aim of this patch-clamp study was to test the antiepileptic potential of capsaicin in prefrontal cortical pyramidal neurons. Capsaicin at a concentration of 60 μM inhibited neuronal excitability. Moreover, later spikes in response to 50-s-long current steps were much smaller in amplitude in the presence of 60 μM capsaicin than in control solution. The tested compound did not influence the membrane potential. Voltage-clamp recordings showed that capsaicin markedly enhanced the use-dependent block of sodium channels (sodium currents were evoked at frequencies of 0,5 Hz and 10 Hz). The presence of the compound shifted the steady-state inactivation curve of sodium channels towards hyperpolarization, which suggests greater inactivation of sodium channels at rest in the presence of capsaicin. Moreover, capsaicin inhibited epileptiform events evoked in three different proepileptic solutions. Capsaicin abolished interictal-like events lasting less than 1 s recorded in zero magnesium solution with an increased potassium ion concentration. The drug also abolished long ictal events evoked in zero magnesium solution containing 4-AP. Moreover, ictal events recorded in zero magnesium solution containing picrotoxin were substantially shortened in the presence of capsaicin. We suggest that capsaicin exerts an antiepileptic effect. The important mechanism behind this phenomenon seems to be the inhibition of sodium channels, which is an effect of many antiepileptic drugs.
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Affiliation(s)
- Michał Pasierski
- Department of Pharmacodynamics, The Medical University of Warsaw, Warsaw, Banacha 1B, 02-097, Poland
| | - Bartłomiej Szulczyk
- Department of Pharmacodynamics, The Medical University of Warsaw, Warsaw, Banacha 1B, 02-097, Poland.
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18
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Capsaicin Exerts Anti-convulsant and Neuroprotective Effects in Pentylenetetrazole-Induced Seizures. Neurochem Res 2020; 45:1045-1061. [PMID: 32036609 DOI: 10.1007/s11064-020-02979-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/07/2020] [Accepted: 01/31/2020] [Indexed: 02/06/2023]
Abstract
The transient receptor potential vanilloid-1 (TRPV1) receptor has been implicated in the development of epileptic seizures. We examined the effect of the TRPV1 agonist capsaicin on epileptic seizures, neuronal injury and oxidative stress in a model of status epilepticus induced in the rat by intraperitoneal (i.p.) injections of pentylenetetrazole (PTZ). Capsaicin was i.p. given at 1 or 2 mg/kg, 30 min before the first PTZ injection. Other groups were i.p. treated with the vehicle or the anti-epileptic drug phenytoin (30 mg/kg) alone or co-administered with capsaicin at 2 mg/kg. Brain levels of malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide, and paraoxonase-1 (PON-1) activity, seizure scores, latency time and PTZ dose required to reach status epilepticus were determined. Histopathological assessment of neuronal damage was done. Results showed that brain MDA decreased by treatment with capsaicin, phenytoin or capsaicin/phenytoin. Nitric oxide decreased by capsaicin or capsaicin/phenytoin. GSH and PON-1 activity increased after capsaicin, phenytoin or capsaicin/phenytoin. Mean total seizure score decreased by 48.8% and 66.3% by capsaicin compared with 78.7% for phenytoin and 69.8% for capsaicin/phenytoin treatment. Only phenytoin increased the latency (115.7%) and threshold dose of PTZ (78.3%). Capsaicin did not decrease the anti-convulsive effect of phenytoin but prevented the phenytoin-induced increase in latency time and threshold dose. Neuronal damage decreased by phenytoin or capsaicin at 2 mg/kg but almost completely prevented by capsaicin/phenytoin. Thus in this model of status epilepticus, capsaicin decreased brain oxidative stress, the severity of seizures and neuronal injury and its co-administration with phenytoin afforded neuronal protection.
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19
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Moriyama H, Nomura S, Kida H, Inoue T, Imoto H, Maruta Y, Fujiyama Y, Mitsushima D, Suzuki M. Suppressive Effects of Cooling Compounds Icilin on Penicillin G-Induced Epileptiform Discharges in Anesthetized Rats. Front Pharmacol 2019; 10:652. [PMID: 31263415 PMCID: PMC6585232 DOI: 10.3389/fphar.2019.00652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 05/20/2019] [Indexed: 11/13/2022] Open
Abstract
More than 30% of patients with epilepsy are refractory and have inadequate seizure control. Focal cortical cooling (FCC) suppresses epileptiform discharges (EDs) in patients with refractory focal cortical epilepsy. However, little is known about the mechanism by which FCC inhibits seizures at 15°C, and FCC treatment is highly invasive. Therefore, new antiepileptic drugs are needed that produce the same effects as FCC but with different mechanisms of action. To address this need, we focused on transient receptor potential melastatin 8 (TRPM8), an ion channel that detects cold, which is activated at 15°C. We examined whether TRPM8 activation suppresses penicillin G (PG)-induced EDs in anesthetized rats. Icilin, a TRPM8 and TRP Ankyrin 1 agonist, was administered after PG injection, and a focal electrocorticogram (ECoG) and cortical temperature were recorded for 4 h. We measured spike amplitude, duration, firing rate, and power density in each band to evaluate the effects of icilin. PG-induced EDs and increased delta, theta, alpha, and beta power spectra were observed in the ECoG. Icilin suppressed EDs while maintaining cortical temperature. In particular, 3.0-mM icilin significantly suppressed PG-induced spike amplitude, duration, and firing rate and improved the increased power density of each band in the EDs to the level of basal activity in the ECoG. These suppressive effects of 3.0-mM icilin on EDs were antagonized by administering N-(3-aminopropyl)-2-[(3-methylphenyl) methoxy]-N-(2-thienylmethyl)-benzamide hydrochloride (AMTB), a selective TRPM8 inhibitor. Our results suggest that TRPM8 activation in epileptic brain regions may be a new therapeutic approach for patients with epilepsy.
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Affiliation(s)
- Hiroshi Moriyama
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Sadahiro Nomura
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.,Epilepsy Center, Yamaguchi University Hospital, Yamaguchi, Japan
| | - Hiroyuki Kida
- Department of Physiology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Takao Inoue
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Hirochika Imoto
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.,Epilepsy Center, Yamaguchi University Hospital, Yamaguchi, Japan
| | - Yuichi Maruta
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Yuichi Fujiyama
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Dai Mitsushima
- Department of Physiology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Michiyasu Suzuki
- Department of Neurosurgery, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
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Ragavendran V, Muthunatesan S, Santhanam V, Arsic B. Synthesis and characterization of cinnamylidene acetone – A study on tuning of band gap by vibrational spectroscopic tools. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.02.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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21
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Leijon SCM, Neves AF, Breza JM, Simon SA, Chaudhari N, Roper SD. Oral thermosensing by murine trigeminal neurons: modulation by capsaicin, menthol and mustard oil. J Physiol 2019; 597:2045-2061. [PMID: 30656684 DOI: 10.1113/jp277385] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/14/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Orosensory thermal trigeminal afferent neurons respond to cool, warm, and nociceptive hot temperatures with the majority activated in the cool range. Many of these thermosensitive trigeminal orosensory afferent neurons also respond to capsaicin, menthol, and/or mustard oil (allyl isothiocyanate) at concentrations found in foods and spices. There is significant but incomplete overlap between afferent trigeminal neurons that respond to oral thermal stimulation and to the above chemesthetic compounds. Capsaicin sensitizes warm trigeminal thermoreceptors and orosensory nociceptors; menthol attenuates cool thermoresponses. ABSTRACT When consumed with foods, mint, mustard, and chili peppers generate pronounced oral thermosensations. Here we recorded responses in mouse trigeminal ganglion neurons to investigate interactions between thermal sensing and the active ingredients of these plants - menthol, allyl isothiocyanate (AITC), and capsaicin, respectively - at concentrations found in foods and commercial hygiene products. We carried out in vivo confocal calcium imaging of trigeminal ganglia in which neurons express GCaMP3 or GCAMP6s and recorded their responses to oral stimulation with thermal and the above chemesthetic stimuli. In the V3 (oral sensory) region of the ganglion, thermoreceptive neurons accounted for ∼10% of imaged neurons. We categorized them into three distinct classes: cool-responsive and warm-responsive thermosensors, and nociceptors (responsive only to temperatures ≥43-45 °C). Menthol, AITC, and capsaicin also elicited robust calcium responses that differed markedly in their latencies and durations. Most of the neurons that responded to these chemesthetic stimuli were also thermosensitive. Capsaicin and AITC increased the numbers of warm-responding neurons and shifted the nociceptor threshold to lower temperatures. Menthol attenuated the responses in all classes of thermoreceptors. Our data show that while individual neurons may respond to a narrow temperature range (or even bimodally), taken collectively, the population is able to report on graded changes of temperature. Our findings also substantiate an explanation for the thermal sensations experienced when one consumes pungent spices or mint.
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Affiliation(s)
- Sara C M Leijon
- Department of Physiology & Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Amanda F Neves
- Department of Physiology & Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Joseph M Breza
- Department of Psychology, Program in Neuroscience, 341J Science Complex, Eastern Michigan University, Ypsilanti, MI, 48197, USA
| | - Sidney A Simon
- Department of Neurobiology, Duke University, Durham, NC, USA
| | - Nirupa Chaudhari
- Department of Physiology & Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA.,Department of Otolaryngology, Miller School of Medicine, University of Miami, and Program in Neuroscience, University of Miami, Miami, FL, USA
| | - Stephen D Roper
- Department of Physiology & Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA.,Department of Otolaryngology, Miller School of Medicine, University of Miami, and Program in Neuroscience, University of Miami, Miami, FL, USA
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22
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Effects of menthol-flavored substances at the cellular level on oral mucosal sites. Dent Res J (Isfahan) 2019; 16:7-11. [PMID: 30745912 PMCID: PMC6340220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND The purpose of this study was to determine the effects of menthol-flavored substances at the cellular level in different mucosal sites of the oral cavity and to compare the cellular changes between individuals without the habit of chewing menthol-flavored substances and individuals with the habit. MATERIALS AND METHODS This was an experimental cytology study including a total of 500 individuals belonging to the age group of 18-45 years based on the inclusion or exclusion criteria. The selected participants were divided into two groups of 250 participants each, based on participants not having the habit of chewing menthol-flavored substances (Group I) and participants having the habit of chewing menthol-flavored substances (Group II). Cytological smears were taken by gently scraping the mucosal surfaces in different sites of the oral mucosa using a wooden spatula and stained with Papanicolaou, analyzed under microscope for any cellular changes. The results were tabulated and statistically analyzed using Chi-square test and Fisher's exact test. P < 0.05 was considered statistically significant. RESULTS Micronuclei seen in all the participants belonging to group with the habit of chewing menthol-flavored substances with a P < 0.001 which was considered highly significant. Alteration in the nuclear-cytoplasmic ratio was also seen P = 0.001, which showed significant at 1% significance level. CONCLUSION Participants with habit of chewing menthol-flavored substances showed the presence of micronuclei and slight alteration in the nuclear-cytoplasmic ratio, which could be directly related to genotoxicity and cell damage.
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23
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Cui Y, Perez S, Venance L. Endocannabinoid-LTP Mediated by CB1 and TRPV1 Receptors Encodes for Limited Occurrences of Coincident Activity in Neocortex. Front Cell Neurosci 2018; 12:182. [PMID: 30026689 PMCID: PMC6041431 DOI: 10.3389/fncel.2018.00182] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/11/2018] [Indexed: 11/25/2022] Open
Abstract
Synaptic efficacy changes, long-term potentiation (LTP) and depression (LTD), underlie various forms of learning and memory. Synaptic plasticity is generally assessed under prolonged activation, whereas learning can emerge from few or even a single trial. Here, we investigated the existence of rapid responsiveness of synaptic plasticity in response to a few number of spikes, in neocortex in a synaptic Hebbian learning rule, the spike-timing-dependent plasticity (STDP). We investigated the effect of lowering the number of pairings from 100 to 50, and 10 on STDP expression, using whole-cell recordings from pyramidal cells in rodent somatosensory cortical brain slices. We found that a low number of paired stimulations induces LTP at neocortical layer 4–2/3 synapses. Besides the asymmetric Hebbian STDP reported in the neocortex induced by 100 pairings, we observed a symmetric anti-Hebbian LTD for 50 pairings and unveiled a unidirectional Hebbian spike-timing-dependent LTP (tLTP) induced by 10–15 pairings. This tLTP was not mediated by NMDA receptor activation but requires CB1 receptors and transient receptor potential vanilloid type-1 (TRPV1) activated by endocannabinoids (eCBs). eCBs have been widely described as mediating short- and long-term synaptic depression. Here, the eCB-tLTP reported at neocortical synapses could constitute a substrate operating in the online learning of new associative memories or during the initial stages of learning. In addition, these findings should provide useful insight into the mechanisms underlying eCB-plasticity occurring during marijuana intoxication.
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Affiliation(s)
- Yihui Cui
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
| | - Sylvie Perez
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology (CIRB), College de France, INSERM U1050, CNRS UMR7241, Paris Sciences et Lettres Research University, Paris, France
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Thompson MF, Poirier GL, Dávila-García MI, Huang W, Tam K, Robidoux M, Dubuke ML, Shaffer SA, Colon-Perez L, Febo M, DiFranza JR, King JA. Menthol enhances nicotine-induced locomotor sensitization and in vivo functional connectivity in adolescence. J Psychopharmacol 2018; 32:332-343. [PMID: 28747086 DOI: 10.1177/0269881117719265] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mentholated cigarettes capture a quarter of the US market, and are disproportionately smoked by adolescents. Menthol allosterically modulates nicotinic acetylcholine receptor function, but its effects on the brain and nicotine addiction are unclear. To determine if menthol is psychoactive, we assessed locomotor sensitization and brain functional connectivity. Adolescent male Sprague Dawley rats were administered nicotine (0.4 mg/kg) daily with or without menthol (0.05 mg/kg or 5.38 mg/kg) for nine days. Following each injection, distance traveled in an open field was recorded. One day after the sensitization experiment, functional connectivity was assessed in awake animals before and after drug administration using magnetic resonance imaging. Menthol (5.38 mg/kg) augmented nicotine-induced locomotor sensitization. Functional connectivity was compared in animals that had received nicotine with or without the 5.38 mg/kg dosage of menthol. Twenty-four hours into withdrawal after the last drug administration, increased functional connectivity was observed for ventral tegmental area and retrosplenial cortex with nicotine+menthol compared to nicotine-only exposure. Upon drug re-administration, the nicotine-only, but not the menthol groups, exhibited altered functional connectivity of the dorsal striatum with the amygdala. Menthol, when administered with nicotine, showed evidence of psychoactive properties by affecting brain activity and behavior compared to nicotine administration alone.
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Affiliation(s)
- Matthew F Thompson
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,2 Department of Biology, Clark University, Worcester, MA, USA
| | - Guillaume L Poirier
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Martha I Dávila-García
- 3 Department of Pharmacology, Howard University College of Medicine, Washington, DC, USA
| | - Wei Huang
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Kelly Tam
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Maxwell Robidoux
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Michelle L Dubuke
- 4 Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,5 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, MA, USA
| | - Scott A Shaffer
- 4 Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,5 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, MA, USA
| | - Luis Colon-Perez
- 6 Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA
| | - Marcelo Febo
- 6 Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA
| | - Joseph R DiFranza
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,7 Department of Family Medicine and Community Health, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jean A King
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,8 Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA.,9 Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
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25
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Oz M, El Nebrisi EG, Yang KHS, Howarth FC, Al Kury LT. Cellular and Molecular Targets of Menthol Actions. Front Pharmacol 2017; 8:472. [PMID: 28769802 PMCID: PMC5513973 DOI: 10.3389/fphar.2017.00472] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/03/2017] [Indexed: 02/04/2023] Open
Abstract
Menthol belongs to monoterpene class of a structurally diverse group of phytochemicals found in plant-derived essential oils. Menthol is widely used in pharmaceuticals, confectionary, oral hygiene products, pesticides, cosmetics, and as a flavoring agent. In addition, menthol is known to have antioxidant, anti-inflammatory, and analgesic effects. Recently, there has been renewed awareness in comprehending the biological and pharmacological effects of menthol. TRP channels have been demonstrated to mediate the cooling actions of menthol. There has been new evidence demonstrating that menthol can significantly influence the functional characteristics of a number of different kinds of ligand and voltage-gated ion channels, indicating that at least some of the biological and pharmacological effects of menthol can be mediated by alterations in cellular excitability. In this article, we examine the results of earlier studies on the actions of menthol with voltage and ligand-gated ion channels.
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Affiliation(s)
- Murat Oz
- Department of Pharmacology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates.,Department of Basic Medical Sciences, College of Medicine, Qatar UniversityDoha, Qatar
| | - Eslam G El Nebrisi
- Department of Pharmacology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Keun-Hang S Yang
- Department of Biological Sciences, Schmid College of Science and Technology, Chapman UniversityOrange, CA, United States
| | - Frank C Howarth
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Lina T Al Kury
- Department of Health Sciences, College of Natural and Health Sciences, Zayed UniversityAbu Dhabi, United Arab Emirates
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26
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V-Ghaffari B, Kouhnavard M, Elbasiouny SM. Mixed-mode oscillations in pyramidal neurons under antiepileptic drug conditions. PLoS One 2017; 12:e0178244. [PMID: 28591171 PMCID: PMC5462370 DOI: 10.1371/journal.pone.0178244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 05/10/2017] [Indexed: 11/19/2022] Open
Abstract
Subthreshold oscillations in combination with large-amplitude oscillations generate mixed-mode oscillations (MMOs), which mediate various spatial and temporal cognition and memory processes and behavioral motor tasks. Although many studies have shown that canard theory is a reliable method to investigate the properties underlying the MMOs phenomena, the relationship between the results obtained by applying canard theory and conductance-based models of neurons and their electrophysiological mechanisms are still not well understood. The goal of this study was to apply canard theory to the conductance-based model of pyramidal neurons in layer V of the Entorhinal Cortex to investigate the properties of MMOs under antiepileptic drug conditions (i.e., when persistent sodium current is inhibited). We investigated not only the mathematical properties of MMOs in these neurons, but also the electrophysiological mechanisms that shape spike clustering. Our results show that pyramidal neurons can display two types of MMOs and the magnitude of the slow potassium current determines whether MMOs of type I or type II would emerge. Our results also indicate that slow potassium currents with large time constant have significant impact on generating the MMOs, as opposed to fast inward currents. Our results provide complete characterization of the subthreshold activities in MMOs in pyramidal neurons and provide explanation to experimental studies that showed MMOs of type I or type II in pyramidal neurons under antiepileptic drug conditions.
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Affiliation(s)
- Babak V-Ghaffari
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science & Mathematics, Wright State University, Dayton, Ohio, United States of America
- * E-mail: (SME); (BV)
| | - M. Kouhnavard
- Malaysia-Japan Int. Inst. of Tech, University Technology Malaysia, Kuala Lumpur, Malaysia
| | - Sherif M. Elbasiouny
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science & Mathematics, Wright State University, Dayton, Ohio, United States of America
- Department of Biomedical, Industrial and Human Factors Engineering, College of Engineering & Computer Science, Wright State University, Dayton, Ohio, United States of America
- * E-mail: (SME); (BV)
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27
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Huang M, Cheng G, Tan H, Qin R, Zou Y, Wang Y, Zhang Y. Capsaicin protects cortical neurons against ischemia/reperfusion injury via down-regulating NMDA receptors. Exp Neurol 2017; 295:66-76. [PMID: 28479337 DOI: 10.1016/j.expneurol.2017.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/13/2017] [Accepted: 05/03/2017] [Indexed: 12/20/2022]
Abstract
Capsaicin, the ingredient responsible for the pungent taste of hot chili peppers, is widely used in the study and management of pain. Recently, its neuroprotective effect has been described in multiple studies. Herein, we investigated the underlying mechanisms for the neuroprotective effect of capsaicin. Direct injection of capsaicin (1 or 3nmol) into the peri-infarct area reduced the infarct volume and improved neurological behavioral scoring and motor coordination function in the middle cerebral artery occlusion (MCAO)/reperfusion model in rats. The time window of the protective effect of capsaicin was within 1h after reperfusion, when excitotoxicity is the main reason of cell death. In cultured cortical neurons, administration of capsaicin attenuated glutamate-induced excitotoxic injury. With respect to the mechanisms of the neuroprotective effect of capsaicin, reduced calcium influx after glutamate stimulation was observed following capsaicin pretreatment in cortical neurons. Trpv1 knock-out abolished the inhibitory effect of capsaicin on glutamate-induced calcium influx and subsequent neuronal death. Reduced expression of GluN1 and GluN2B, subunits of NMDA receptor, was examined after capsaicin treatment in cortical neurons. In summary, our studies reveal that the neuroprotective effect of capsaicin in cortical neurons is TRPV1-dependent and down-regulation of the expression and function of NMDA receptors contributes to the protection afforded by capsaicin.
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Affiliation(s)
- Ming Huang
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China
| | - Gen Cheng
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China
| | - Han Tan
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China
| | - Rui Qin
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China
| | - Yimin Zou
- Neurobiology Section, Biological Sciences Division, University of California, La Jolla, San Diego, CA 92093, USA
| | - Yun Wang
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China; PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Ying Zhang
- Neuroscience Research Institute, Department of Neurobiology, School of Basic Medical Sciences, Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University Health Science Center, Beijing 100191, China.
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28
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Dual effects of eugenol on the neuronal excitability: An in vitro study. Neurotoxicology 2016; 58:84-91. [PMID: 27894698 DOI: 10.1016/j.neuro.2016.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/10/2016] [Accepted: 11/24/2016] [Indexed: 11/23/2022]
Abstract
Besides its well-known actions on sensory afferents, eugenol also affects general excitability of the nervous system, but the mechanisms involved in the recent effect, especially through modulation of ion channels, have received much less attention. In this study, we studied the effects of eugenol on the excitability of central neurons of land snail Caucasotachea atrolabiata and tried to elucidate the underlying ionic mechanisms. The lower concentration of eugenol (0.5mM) reversibly reduced the frequency of spontaneous action potentials that was associated with elevation of threshold, reduction of maximum slope of rising phase and prolongation of actin potentials. These effects were mimicked by riluzole, suggesting that they might be mediated by inhibition of Na+ channels. Eugenol also prolonged the single-spike afterhyperpolarization and post stimulus inhibitory period, but these effects seemed to be consequent to action potential prolongation that indirectly augment Ca2+ inward currents and Ca2+-activated K+ currents. This concentration of eugenol was also able to prevent or abolish pentylenetetrazole-induced epileptiform activity. On the other hand, a higher concentration of eugenol (2mM) reversibly increased the frequency of action potentials and then induced epileptiform activity in majority of treated neurons. Several criteria suggest that the inhibition of K+ channels by higher concentration of eugenol and indirect augmentation of Ca2+ currents are central to the hyperexcitability and epileptiform activity induced by eugenol. Our findings indicate that while low concentration of eugenol could have antiepileptic properties, at higher concentration it induces epileptiform activity. It seems that does dependent inhibition of the ionic currents underlying rising and falling phases of action potential is relevant to the eugenol suppressant and excitatory actions, respectively.
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29
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Effects of monoterpenes on ion channels of excitable cells. Pharmacol Ther 2015; 152:83-97. [PMID: 25956464 DOI: 10.1016/j.pharmthera.2015.05.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 04/23/2015] [Indexed: 11/20/2022]
Abstract
Monoterpenes are a structurally diverse group of phytochemicals and a major constituent of plant-derived 'essential oils'. Monoterpenes such as menthol, carvacrol, and eugenol have been utilized for therapeutical purposes and food additives for centuries and have been reported to have anti-inflammatory, antioxidant and analgesic actions. In recent years there has been increasing interest in understanding the pharmacological actions of these molecules. There is evidence indicating that monoterpenes can modulate the functional properties of several types of voltage and ligand-gated ion channels, suggesting that some of their pharmacological actions may be mediated by modulations of ion channel function. In this report, we review the literature concerning the interaction of monoterpenes with various ion channels.
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