551
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Fleetwood-Walker S, Proudfoot C, Garry E, Allchorne A, Vinuela-Fernandez I, Mitchell R. Cold comfort pharm. Trends Pharmacol Sci 2007; 28:621-8. [DOI: 10.1016/j.tips.2007.10.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 09/06/2007] [Accepted: 10/29/2007] [Indexed: 01/09/2023]
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552
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Bang S, Kim KY, Yoo S, Kim YG, Hwang SW. Transient receptor potential A1 mediates acetaldehyde-evoked pain sensation. Eur J Neurosci 2007; 26:2516-23. [PMID: 17970723 DOI: 10.1111/j.1460-9568.2007.05882.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Six transient receptor potential (TRP) ion channels expressed in the sensory afferents play an important role as body thermosensors and also as peripheral pain detectors. It is known that a number of natural compounds specifically activate those sensory neuronal TRP channels, and a well-known example is cinnamaldehyde for TRPA1. Here we show that human and mouse TRPA1 are activated by acetaldehyde, an intermediate substance of ethanol metabolism, in the HEK293T cell heterologous expression system and in cultured mouse trigeminal neurons. Acetaldehyde failed to activate other temperature-sensitive TRP channels expressed in sensory neurons. TRPA1 antagonists camphor and gadolinium, and a general TRP blocker ruthenium red inhibited TRPA1 activation by acetaldehyde. Camphor, gadolinium and ruthenium red also suppressed the acute nociceptive behaviors induced by the intradermal administration of acetaldehyde into the mouse footpads. Intradermal co-application of prostaglandin E2 and acetaldehyde greatly potentiated the acetaldehyde-induced nociceptive responses, and this effect was reversed by treatment with the TRPA1 antagonist camphor. These results suggest that acetaldehyde causes nociception via TRPA1 activation. Our data may also help elucidate the mechanisms underlying acetaldehyde-related pathological symptoms such as hangover pain.
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Affiliation(s)
- Sangsu Bang
- Korea University Graduate School of Medicine, Seoul 136-705, Korea
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553
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Zanotto KL, Iodi Carstens M, Carstens E. Cross-desensitization of responses of rat trigeminal subnucleus caudalis neurons to cinnamaldehyde and menthol. Neurosci Lett 2007; 430:29-33. [PMID: 18060696 DOI: 10.1016/j.neulet.2007.10.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 09/28/2007] [Accepted: 10/13/2007] [Indexed: 11/29/2022]
Abstract
Most cold-sensitive subnucleus caudalis (Vc) neurons are also excited by the TRPM8 agonist menthol and the TRPA1 agonist cinnamaldehyde (CA). We investigated how interactions among menthol, CA and noxious cooling and heating of the tongue affected responses of superficial Vc units recorded in thiopental-anesthetized rats. Units responded to 1% CA which enhanced cold- and heat-evoked responses 5 min later. They responded more strongly to 10% CA which initially depressed cold responses, followed by enhancement at 5 min without affecting responses to heat. Following 10% CA, the mean response to 1% menthol was significantly lower than when menthol was tested first. After menthol, the subsequent response to CA was significantly weaker compared to the mean CA-evoked response when it was tested first. These results demonstrate mutual cross-desensitization between CA and menthol. The response to CA was enhanced following prior application of 10% ethanol (menthol vehicle). Prior application of menthol did not prevent the biphasic effect of 10% CA on cold-evoked responses, nor did prior application of CA prevent menthol enhancement of cold-evoked responses. Responses to noxious heat were unaffected by 10% CA and menthol regardless of the order of chemical presentation. These data indicate that superficial Vc neurons receive convergent input from primary afferents expressing TRPM8 and TRPA1. The mutual cross-desensitization between CA and menthol, and differential modulation of cold- vs. heat-evoked responses, suggests a direct inhibition of TRPM8 and TRPA1 expressed in peripheral nerve endings by CA and menthol, respectively, rather than a central site of interaction.
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Affiliation(s)
- Karen L Zanotto
- Section of Neurobiology, Physiology and Behavior University of California, Davis, CA 95616, USA
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554
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Merrill AW, Cuellar JM, Judd JH, Carstens MI, Carstens E. Effects of TRPA1 agonists mustard oil and cinnamaldehyde on lumbar spinal wide-dynamic range neuronal responses to innocuous and noxious cutaneous stimuli in rats. J Neurophysiol 2007; 99:415-25. [PMID: 17942619 DOI: 10.1152/jn.00883.2007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mustard oil [allyl isothiocyanate (AITC)] and cinnamaldehyde (CA), agonists of the ion channel TRPA1 expressed in sensory neurons, elicit a burning sensation and heat hyperalgesia. We tested whether these phenomena are reflected in the responses of lumbar spinal wide-dynamic range (WDR) neurons recorded in pentobarbital-anesthetized rats. Responses to electrical and graded mechanical and noxious thermal stimulation were tested before and after cutaneous application of AITC or CA. Repetitive application of AITC initially increased the firing rate of 52% of units followed by rapid desensitization that persisted when AITC was reapplied 30 min later. Responses to noxious thermal, but not mechanical, stimuli were significantly enhanced irrespective of whether the neuron was directly activated by AITC. Windup elicited by percutaneous or sciatic nerve electrical stimulation was significantly reduced post-AITC. These results indicate that AITC produced central inhibition and peripheral sensitization of heat nociceptors. CA did not directly excite WDR neurons, and significantly enhanced responses to noxious heat while not affecting windup or responses to skin cooling or mechanical stimulation, indicating a peripheral sensitization of heat nociceptors.
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Affiliation(s)
- Austin W Merrill
- Section of Neurobiology, Physiology and Behavior, University of California, Davis, 1 Shields Ave., Davis, CA 95616, USA
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555
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Leith JL, Wilson AW, Donaldson LF, Lumb BM. Cyclooxygenase-1-derived prostaglandins in the periaqueductal gray differentially control C- versus A-fiber-evoked spinal nociception. J Neurosci 2007; 27:11296-305. [PMID: 17942724 PMCID: PMC6673041 DOI: 10.1523/jneurosci.2586-07.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 08/23/2007] [Accepted: 08/28/2007] [Indexed: 11/21/2022] Open
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) exert analgesic effects by inhibiting peripheral cyclooxygenases (COXs). It is now clear that these drugs also have central actions that include the modulation of descending control of spinal nociception from the midbrain periaqueductal gray (PAG). Descending control is a powerful determinant of the pain experience and is thus a potential target for analgesic drugs, including COX inhibitors. Noxious information from the periphery is conveyed to the spinal cord in A- and C-fiber nociceptors, which convey different qualities of the pain signal and have different roles in chronic pain. This in vivo study used different rates of skin heating to preferentially activate A- or C-heat nociceptors to further investigate the actions of COX inhibitors and prostaglandins in the PAG on spinal nociceptive processing. The results significantly advance our understanding of the central mechanisms underlying the actions of NSAIDs and prostaglandins by demonstrating that (1) in the PAG, it is COX-1 and not COX-2 that is responsible for acute antinociceptive effects of NSAIDs in vivo; (2) these effects are only evoked from the opioid-sensitive ventrolateral PAG; and (3) prostaglandins in the PAG exert tonic facilitatory control that targets C- rather than A-fiber-mediated spinal nociception. This selectivity of control is of particular significance given the distinct roles of A- and C-nociceptors in acute and chronic pain. Thus, effects of centrally acting prostaglandins are pivotal, we suggest, to both the understanding of nociceptive processing and the development of new analgesic drugs.
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Affiliation(s)
- J. Lianne Leith
- Department of Physiology, University of Bristol, Bristol BS8 1TD, United Kingdom, and
| | - Alex W. Wilson
- Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline, Harlow, Essex CM19 5AW, United Kingdom
| | - Lucy F. Donaldson
- Department of Physiology, University of Bristol, Bristol BS8 1TD, United Kingdom, and
| | - Bridget M. Lumb
- Department of Physiology, University of Bristol, Bristol BS8 1TD, United Kingdom, and
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556
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Karashima Y, Damann N, Prenen J, Talavera K, Segal A, Voets T, Nilius B. Bimodal action of menthol on the transient receptor potential channel TRPA1. J Neurosci 2007; 27:9874-84. [PMID: 17855602 PMCID: PMC6672629 DOI: 10.1523/jneurosci.2221-07.2007] [Citation(s) in RCA: 386] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
TRPA1 is a calcium-permeable nonselective cation transient receptor potential (TRP) channel that functions as an excitatory ionotropic receptor in nociceptive neurons. TRPA1 is robustly activated by pungent substances in mustard oil, cinnamon, and garlic and mediates the inflammatory actions of environmental irritants and proalgesic agents. Here, we demonstrate a bimodal sensitivity of TRPA1 to menthol, a widely used cooling agent and known activator of the related cold receptor TRPM8. In whole-cell and single-channel recordings of heterologously expressed TRPA1, submicromolar to low-micromolar concentrations of menthol cause channel activation, whereas higher concentrations lead to a reversible channel block. In addition, we provide evidence for TRPA1-mediated menthol responses in mustard oil-sensitive trigeminal ganglion neurons. Our data indicate that TRPA1 is a highly sensitive menthol receptor that very likely contributes to the diverse psychophysical sensations after topical application of menthol to the skin or mucous membranes of the oral and nasal cavities.
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Affiliation(s)
- Yuji Karashima
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Nils Damann
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Jean Prenen
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Karel Talavera
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Andrei Segal
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Thomas Voets
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Bernd Nilius
- Laboratorium voor Fysiologie, Campus Gasthuisberg, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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557
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Ji G, Zhou S, Kochukov MY, Westlund KN, Carlton SM. Plasticity in intact A delta- and C-fibers contributes to cold hypersensitivity in neuropathic rats. Neuroscience 2007; 150:182-93. [PMID: 17945425 DOI: 10.1016/j.neuroscience.2007.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 09/10/2007] [Accepted: 09/12/2007] [Indexed: 10/22/2022]
Abstract
Cold hypersensitivity is a common sensory abnormality accompanying peripheral neuropathies and is difficult to treat. Progress has been made in understanding peripheral mechanisms underlying neuropathic pain but little is known concerning peripheral mechanisms of cold hypersensitivity. The aim of this study was to analyze the contribution of uninjured primary afferents to the cold hypersensitivity that develops in neuropathic rats. Rats with a lumbar 5 (L5) and L6 spinal nerve ligation (SNL, Chung model) but not sham, developed mechanical allodynia, evidenced by decreased paw withdrawal thresholds and increased magnitude of response to von Frey stimulation. Cold hypersensitivity also developed in SNL but not sham rats, evidenced by enhanced nociceptive behaviors induced by placement on a cold plate (6 degrees C) or application of icilin (a transient receptor potential M8 (TRPM8)/transient receptor potential A1 (TRPA1) receptor agonist) to nerve-injured hind paws. Single fiber recordings demonstrated that the mean conduction velocities of intact L4 cutaneous A delta- and C-fibers were not different between naive and SNL rats; however, mechanical thresholds of the A delta- but not the C-fibers were significantly decreased in SNL compared with naive. There was a higher prevalence of C-mechanoheat-cold (CMHC) fibers in SNL compared with naive, but the overall percentage of cold-sensitive C-fibers was not significantly increased compared with naive. This was in contrast to the numerous changes in A delta-fibers: the percentage of L4 cold sensitive A delta-, but not C-fibers, was significantly increased, the percentage of L4 icilin-sensitive A delta-, but not C-fibers, was significantly increased, the icilin-induced activity of L4 A delta-, but not C-fibers, was significantly increased. Icilin-induced activity was blocked by the TRPA1 antagonist Ruthenium Red. The results indicate plasticity in both A delta- and C-uninjured fibers, but A delta fibers appear to provide a major contribution to cold hypersensitivity in neuropathic rats.
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Affiliation(s)
- G Ji
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Marine Biomedical Institute, 301 University Boulevard, Galveston, TX 77555-1069, USA
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558
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Dai Y, Wang S, Tominaga M, Yamamoto S, Fukuoka T, Higashi T, Kobayashi K, Obata K, Yamanaka H, Noguchi K. Sensitization of TRPA1 by PAR2 contributes to the sensation of inflammatory pain. J Clin Invest 2007; 117:1979-87. [PMID: 17571167 PMCID: PMC1888570 DOI: 10.1172/jci30951] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Accepted: 04/10/2007] [Indexed: 12/17/2022] Open
Abstract
Proinflammatory agents trypsin and mast cell tryptase cleave and activate PAR2, which is expressed on sensory nerves to cause neurogenic inflammation. Transient receptor potential A1 (TRPA1) is an excitatory ion channel on primary sensory nerves of pain pathway. Here, we show that a functional interaction of PAR2 and TRPA1 in dorsal root ganglion (DRG) neurons could contribute to the sensation of inflammatory pain. Frequent colocalization of TRPA1 with PAR2 was found in rat DRG neurons. PAR2 activation increased the TRPA1 currents evoked by its agonists in HEK293 cells transfected with TRPA1, as well as DRG neurons. Application of phospholipase C (PLC) inhibitors or phosphatidylinositol-4,5-bisphosphate (PIP(2)) suppressed this potentiation. Decrease of plasma membrane PIP(2) levels through antibody sequestration or PLC-mediated hydrolysis mimicked the potentiating effects of PAR2 activation at the cellular level. Thus, the increased TRPA1 sensitivity may have been due to activation of PLC, which releases the inhibition of TRPA1 from plasma membrane PIP(2). These results identify for the first time to our knowledge a sensitization mechanism of TRPA1 and a novel mechanism through which trypsin or tryptase released in response to tissue inflammation might trigger the sensation of pain by TRPA1 activation.
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Affiliation(s)
- Yi Dai
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Shenglan Wang
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Makoto Tominaga
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Satoshi Yamamoto
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Tetsuo Fukuoka
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Tomohiro Higashi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Kimiko Kobayashi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Koichi Obata
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Hiroki Yamanaka
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo, Japan.
Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo, Japan.
Department of Physiological Sciences, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan.
Department of Physiology, Hyogo College of Medicine, Hyogo, Japan
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559
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Hazari MS, Rowan WH, Winsett DW, Ledbetter AD, Haykal-Coates N, Watkinson WP, Costa DL. Potentiation of pulmonary reflex response to capsaicin 24h following whole-body acrolein exposure is mediated by TRPV1. Respir Physiol Neurobiol 2007; 160:160-71. [PMID: 17950047 DOI: 10.1016/j.resp.2007.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 09/06/2007] [Accepted: 09/11/2007] [Indexed: 11/26/2022]
Abstract
Pulmonary C-fibers are stimulated by irritant air pollutants producing apnea, bronchospasm, and decrease in HR. Chemoreflex responses resulting from C-fiber activation are sometimes mediated by TRPV1 and release of substance P. While acrolein has been shown to stimulate C-fibers, the persistence of acrolein effects and the role of C-fibers in these responses are unknown. These experiments were designed to determine the effects of whole-body acrolein exposure and pulmonary chemoreflex response post-acrolein. Rats were exposed to either air or 3 ppm acrolein for 3 h while ventilatory function and HR were measured; 1-day later response to capsaicin challenge was measured in anesthetized rats. Rats experienced apnea and decrease in HR upon exposure to acrolein, which was not affected by either TRPV1 antagonist or NK(1)R antagonist pretreatment. Twenty-four hours later, capsaicin caused apnea and bronchoconstriction in control rats, which was potentiated in rats exposed to acrolein. Pretreatment with TRPV1 antagonist or NK(1)R antagonist prevented potentiation of apneic response and bronchoconstriction 24h post-exposure. These data suggest that although potentiation of pulmonary chemoreflex response 24h post-acrolein is mediated by TRPV1 and release of substance P, cardiopulmonary inhibition during whole-body acrolein exposure is mediated through other mechanisms.
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Affiliation(s)
- Mehdi S Hazari
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC 27599-7270, United States.
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560
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Albin KC, Carstens MI, Carstens E. Modulation of oral heat and cold pain by irritant chemicals. Chem Senses 2007; 33:3-15. [PMID: 17728277 DOI: 10.1093/chemse/bjm056] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Common food irritants elicit oral heat or cool sensations via actions at thermosensitive transient receptor potential (TRP) channels. We used a half-tongue, 2-alternative forced-choice procedure coupled with bilateral pain intensity ratings to investigate irritant effects on heat and cold pain. The method was validated in a bilateral thermal difference detection task. Capsaicin, mustard oil, and cinnamaldehyde enhanced lingual heat pain elicited by a 49 degrees C stimulus. Mustard oil and cinnamaldehyde weakly enhanced lingual cold pain (9.5 degrees C), whereas capsaicin had no effect. Menthol significantly enhanced cold pain and weakly reduced heat pain. To address if capsaicin's effect was due to summation of perceptually similar thermal and chemical sensations, one-half of the tongue was desensitized by application of capsaicin. Upon reapplication, capsaicin elicited little or no irritant sensation yet still significantly enhanced heat pain on the capsaicin-treated side, ruling out summation. In a third experiment, capsaicin significantly enhanced pain ratings to graded heat stimuli (47 degrees C to 50 degrees C) resulting in an upward shift of the stimulus-response function. Menthol may induce cold hyperalgesia via enhanced thermal gating of TRPM8 in peripheral fibers. Capsaicin, mustard oil, and cinnamaldehyde may induce heat hyperalgesia via enhanced thermal gating of TRPV1 that is coexpressed with TRPA1 in peripheral nociceptors.
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Affiliation(s)
- Kelly C Albin
- Section of Neurobiology, Physiology and Behavior, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA
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561
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Penuelas A, Tashima K, Tsuchiya S, Matsumoto K, Nakamura T, Horie S, Yano S. Contractile effect of TRPA1 receptor agonists in the isolated mouse intestine. Eur J Pharmacol 2007; 576:143-50. [PMID: 17825279 DOI: 10.1016/j.ejphar.2007.08.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 08/04/2007] [Accepted: 08/13/2007] [Indexed: 12/26/2022]
Abstract
TRPA1 is a member of the transient receptor potential (TRP) channel family expressed in sensory neurons. The present study focused on the effects of TRPA1 activation on contractile responses in isolated mouse intestine preparations. The jejunum, ileum, and proximal and distal colon were surgically isolated from male ddY mice. Intestinal motility was recorded as changes in isotonic tension. TRPA1, TRPM8, and TRPV1 expressions were examined by reverse transcription-polymerase chain reaction (RT-PCR). A TRPA1 agonist allyl isothiocyanate (AITC) dose-dependently induced contractions in the proximal and distal colon, whereas in the jejunum and ileum, even 100 muM AITC caused very little contraction. Likewise, a TRPA1 and TRPM8 agonist icilin, a TRPA1 agonist allicin, and a TRPV1 agonist capsaicin induced contractions in the colon. However, a TRPM8 agonist menthol induced long-lasting relaxation in the colon. Repeated exposure to AITC produced desensitization of its own contraction in the colon. Moreover, contractions induced by AITC generate cross-desensitization with icilin and capsaicin. Tetrodotoxin completely abolished AITC-induced contractions in the colon, whereas atropine significantly attenuated AITC-induced contractions in the distal colon, but not in the proximal colon. Menthol-induced relaxation in the colon was not inhibited by tetrodotoxin and atropine. RT-PCR analysis revealed the expression of TRPA1 and TRPV1, but not TRPM8, throughout the mouse intestine. These results suggest that TRPA1, but not TRPM8, are functionally expressed in the enteric nervous system throughout the mouse intestine on neurons that may also co-express TRPV1, yet the contractile responses to TRPA1 activation differ depending on their location along the intestine.
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Affiliation(s)
- Angelica Penuelas
- Department of Molecular Pharmacology and Pharmacotherapeutics, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8675, Japan
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562
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Alvarado LT, Perry GM, Hargreaves KM, Henry MA. TRPM8 Axonal expression is decreased in painful human teeth with irreversible pulpitis and cold hyperalgesia. J Endod 2007; 33:1167-71. [PMID: 17889683 PMCID: PMC2727874 DOI: 10.1016/j.joen.2007.06.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 06/22/2007] [Accepted: 06/22/2007] [Indexed: 01/20/2023]
Abstract
Pulpitis pain might be triggered by a cold stimulus, yet the cellular mechanisms responsible for this phenomenon are largely unknown. One possible mechanism involves the direct activation of cold-responsive thermoreceptors. The purpose of this study was to evaluate the possible role of the TRPM8 thermoreceptor in cold-mediated noxious pulpal pain mechanisms by comparing expression patterns in pulpal nerves from healthy control molars to cold-sensitive painful molars with irreversible pulpitis. Samples were identically processed with the indirect immunofluorescence method, and images were obtained with confocal microscopy. The immunofluorescence intensity and area occupied by TRPM8 within N52/PGP9.5-identified nerve fibers were quantified. Results showed that relative to normal samples, TRPM8 nerve area expression was significantly less in the cold-sensitive painful samples (34.9% vs 8%, P <0.03), but with no significant difference in immunofluorescence intensity between the 2 groups. These results suggest that TRPM8 is most likely not involved in cold-mediated noxious pulpal pain mechanisms.
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Affiliation(s)
- Lisa T Alvarado
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
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563
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McNamara CR, Mandel-Brehm J, Bautista DM, Siemens J, Deranian KL, Zhao M, Hayward NJ, Chong JA, Julius D, Moran MM, Fanger CM. TRPA1 mediates formalin-induced pain. Proc Natl Acad Sci U S A 2007; 104:13525-30. [PMID: 17686976 PMCID: PMC1941642 DOI: 10.1073/pnas.0705924104] [Citation(s) in RCA: 940] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The formalin model is widely used for evaluating the effects of analgesic compounds in laboratory animals. Injection of formalin into the hind paw induces a biphasic pain response; the first phase is thought to result from direct activation of primary afferent sensory neurons, whereas the second phase has been proposed to reflect the combined effects of afferent input and central sensitization in the dorsal horn. Here we show that formalin excites sensory neurons by directly activating TRPA1, a cation channel that plays an important role in inflammatory pain. Formalin induced robust calcium influx in cells expressing cloned or native TRPA1 channels, and these responses were attenuated by a previously undescribed TRPA1-selective antagonist. Moreover, sensory neurons from TRPA1-deficient mice lacked formalin sensitivity. At the behavioral level, pharmacologic blockade or genetic ablation of TRPA1 produced marked attenuation of the characteristic flinching, licking, and lifting responses resulting from intraplantar injection of formalin. Our results show that TRPA1 is the principal site of formalin's pain-producing action in vivo, and that activation of this excitatory channel underlies the physiological and behavioral responses associated with this model of pain hypersensitivity.
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Affiliation(s)
| | - Josh Mandel-Brehm
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
| | - Diana M. Bautista
- Departments of Physiology and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143
| | - Jan Siemens
- Departments of Physiology and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143
| | - Kari L. Deranian
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
| | - Michael Zhao
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
| | - Neil J. Hayward
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
| | - Jayhong A. Chong
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
| | - David Julius
- Departments of Physiology and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143
- To whom correspondence may be addressed. E-mail: or
| | - Magdalene M. Moran
- *Hydra Biosciences, Inc., 790 Memorial Drive, Cambridge, MA 02139; and
- To whom correspondence may be addressed. E-mail: or
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564
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Bíró T, Tóth BI, Marincsák R, Dobrosi N, Géczy T, Paus R. TRP channels as novel players in the pathogenesis and therapy of itch. Biochim Biophys Acta Mol Basis Dis 2007; 1772:1004-21. [PMID: 17462867 DOI: 10.1016/j.bbadis.2007.03.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 03/08/2007] [Accepted: 03/08/2007] [Indexed: 11/23/2022]
Abstract
Itch (pruritus) is a sensory phenomenon characterized by a (usually) negative affective component and the initiation of a special behavioral act, i.e. scratching. Older studies predominantly have interpreted itch as a type of pain. Recent neurophysiological findings, however, have provided compelling evidence that itch (although it indeed has intimate connections to pain) rather needs to be understood as a separate sensory modality. Therefore, a novel pruriceptive system has been proposed, within which itch-inducing peripheral mediators (pruritogens), itch-selective receptors (pruriceptors), sensory afferents and spinal cord neurons, and defined, itch-processing central nervous system regions display complex, layered responses to itch. In this review, we begin with a current overview on the neurophysiology of pruritus, and distinguish it from that of pain. We then focus on the functional characteristics of the large family of transient receptor potential (TRP) channels in skin-coupled sensory mechanisms, including itch and pain. In particular, we argue that - due to their expression patterns, activation mechanisms, regulatory roles, and pharmacological sensitivities - certain thermosensitive TRP channels are key players in pruritus pathogenesis. We close by proposing a novel, TRP-centered concept of pruritus pathogenesis and sketch important future experimental directions towards the therapeutic targeting of TRP channels in the clinical management of itch.
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Affiliation(s)
- Tamás Bíró
- Department of Physiology, University of Debrecen, Medical and Health Science Center, Research Center for Molecular Medicine, 4032 Debrecen, Hungary.
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565
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Levine JD, Alessandri-Haber N. TRP channels: Targets for the relief of pain. Biochim Biophys Acta Mol Basis Dis 2007; 1772:989-1003. [PMID: 17321113 DOI: 10.1016/j.bbadis.2007.01.008] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 01/12/2007] [Accepted: 01/16/2007] [Indexed: 02/01/2023]
Abstract
Patients with inflammatory or neuropathic pain experience hypersensitivity to mechanical, thermal and/or chemical stimuli. Given the diverse etiologies and molecular mechanisms of these pain syndromes, an approach to developing successful therapies may be to target ion channels that contribute to the detection of thermal, mechanical and chemical stimuli and promote the sensitization and activation of nociceptors. Transient Receptor Potential (TRP) channels have emerged as a family of evolutionarily conserved ligand-gated ion channels that contribute to the detection of physical stimuli. Six TRPs (TRPV1, TRPV2, TRPV3, TRPV4, TRPM8 and TRPA1) have been shown to be expressed in primary afferent nociceptors, pain sensing neurons, where they act as transducers for thermal, chemical and mechanical stimuli. This short review focuses on their contribution to pain hypersensitivity associated with peripheral inflammatory and neuropathic pain states.
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Affiliation(s)
- Jon D Levine
- Department of Oral and Maxillofacial Surgery, Box 0440, University of California, San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0440, USA
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566
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Akopian AN, Ruparel NB, Jeske NA, Hargreaves KM. Transient receptor potential TRPA1 channel desensitization in sensory neurons is agonist dependent and regulated by TRPV1-directed internalization. J Physiol 2007; 583:175-93. [PMID: 17584831 PMCID: PMC2277224 DOI: 10.1113/jphysiol.2007.133231] [Citation(s) in RCA: 215] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The pharmacological desensitization of receptors is a fundamental mechanism for regulating the activity of neuronal systems. The TRPA1 channel plays a key role in the processing of noxious information and can undergo functional desensitization by unknown mechanisms. Here we show that TRPA1 is desensitized by homologous (mustard oil; a TRPA1 agonist) and heterologous (capsaicin; a TRPV1 agonist) agonists via Ca2+-independent and Ca2+-dependent pathways, respectively, in sensory neurons. The pharmacological desensitization of TRPA1 by capsaicin and mustard oil is not influenced by activation of protein phosphatase 2B. However, it is regulated by phosphatidylinositol-4,5-bisphosphate depletion after capsaicin, but not mustard oil, application. Using a biosensor, we establish that capsaicin, unlike mustard oil, consistently activates phospholipase C in sensory neurons. We next demonstrate that TRPA1 desensitization is regulated by TRPV1, and it appears that mustard oil-induced TRPA1 internalization is prevented by coexpression with TRPV1 in a heterologous expression system and in sensory neurons. In conclusion, we propose novel mechanisms whereby TRPA1 activity undergoes pharmacological desensitization through multiple cellular pathways that are agonist dependent and modulated by TRPV1.
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Affiliation(s)
- Armen N Akopian
- Department of Endodontics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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567
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Sawada Y, Hosokawa H, Hori A, Matsumura K, Kobayashi S. Cold sensitivity of recombinant TRPA1 channels. Brain Res 2007; 1160:39-46. [PMID: 17588549 DOI: 10.1016/j.brainres.2007.05.047] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 05/11/2007] [Accepted: 05/13/2007] [Indexed: 10/23/2022]
Abstract
TRPM8 and TRPA1, members of the transient receptor potential (TRP) channel family, are candidates for cooling-activated receptors. It is accepted that TRPM8 responds to moderate cooling, although it is controversial whether TRPA1 responds to deep cooling. Here, using Ca(2+) imaging and/or patch-clamp recordings, we examined the thermal sensitivity of primary cultured dorsal root ganglion (DRG) neurons and mouse TRPA1-expressing human embryonic kidney (HEK) 293 cells. In a subset of cultured mouse DRG neurons, deep cooling (5-18 degrees C) and allyl isothiocyanate (AITC, agonist of TRPA1) induced increases in intracellular Ca(2+) level. Most AITC-sensitive (TRPA1-expressing) neurons responded to deep cooling. In TRPA1-expressing HEK293 cells, deep cooling and AITC-induced Ca(2+) responses and whole-cell currents. In inside-out patches excised from TRPA1-expressing HEK293 cells, deep cooling, and AITC activated the same channels, which were inhibited by camphor (antagonist for TRPA1). When temperature was decreased below 18 degrees C, unit conductance of the channel decreased but open probability of it increased. Deep cooling-induced increase of the open probability of TRPA1 may underlie the increase in whole-cell currents induced by deep cooling. It is concluded that TRPA1 is a deep cooling-activated channel, which supports the previous findings that TRPA1 responds to deep cooling.
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Affiliation(s)
- Yosuke Sawada
- Division of Biological Information, Department of Intelligence Science and Technology, Graduate School of Informatics, Kyoto University, Kyoto, Japan
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568
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Differential expression of the capsaicin receptor TRPV1 and related novel receptors TRPV3, TRPV4 and TRPM8 in normal human tissues and changes in traumatic and diabetic neuropathy. BMC Neurol 2007; 7:11. [PMID: 17521436 PMCID: PMC1892784 DOI: 10.1186/1471-2377-7-11] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Accepted: 05/23/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Transient receptor potential (TRP) receptors expressed by primary sensory neurons mediate thermosensitivity, and may play a role in sensory pathophysiology. We previously reported that human dorsal root ganglion (DRG) sensory neurons co-expressed TRPV1 and TRPV3, and that these were increased in injured human DRG. Related receptors TRPV4, activated by warmth and eicosanoids, and TRPM8, activated by cool and menthol, have been characterised in pre-clinical models. However, the role of TRPs in common clinical sensory neuropathies needs to be established. METHODS We have studied TRPV1, TRPV3, TRPV4, and TRPM8 in nerves (n = 14) and skin from patients with nerve injury, avulsed dorsal root ganglia (DRG) (n = 11), injured spinal nerve roots (n = 9), diabetic neuropathy skin (n = 8), non-diabetic neuropathic nerve biopsies (n = 6), their respective control tissues, and human post mortem spinal cord, using immunohistological methods. RESULTS TRPV1 and TRPV3 were significantly increased in injured brachial plexus nerves, and TRPV1 in hypersensitive skin after nerve repair, whilst TRPV4 was unchanged. TRPM8 was detected in a few medium diameter DRG neurons, and was unchanged in DRG after avulsion injury, but was reduced in axons and myelin in injured nerves. In diabetic neuropathy skin, TRPV1 expressing sub- and intra-epidermal fibres were decreased, as was expression in surviving fibres. TRPV1 was also decreased in non-diabetic neuropathic nerves. Immunoreactivity for TRPV3 was detected in basal keratinocytes, with a significant decrease of TRPV3 in diabetic skin. TRPV1-immunoreactive nerves were present in injured dorsal spinal roots and dorsal horn of control spinal cord, but not in ventral roots, while TRPV3 and TRPV4 were detected in spinal cord motor neurons. CONCLUSION The accumulation of TRPV1 and TRPV3 in peripheral nerves after injury, in spared axons, matches our previously reported changes in avulsed DRG. Reduction of TRPV1 levels in nerve fibres in diabetic neuropathy skin may result from the known decrease of nerve growth factor (NGF) levels. The role of TRPs in keratinocytes is unknown, but a relationship to changes in NGF levels, which is produced by keratinocytes, deserves investigation. TRPV1 represents a more selective therapeutic target than other TRPs for pain and hypersensitivity, particularly in post-traumatic neuropathy.
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569
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Frederick J, Buck ME, Matson DJ, Cortright DN. Increased TRPA1, TRPM8, and TRPV2 expression in dorsal root ganglia by nerve injury. Biochem Biophys Res Commun 2007; 358:1058-64. [PMID: 17517374 DOI: 10.1016/j.bbrc.2007.05.029] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 05/05/2007] [Indexed: 01/06/2023]
Abstract
Thermosensitive TRP channels display unique thermal responses, suggesting distinct roles mediating sensory transmission of temperature. However, whether relative expression of these channels in dorsal root ganglia (DRG) is altered in nerve injury is unknown. We developed a multiplex ribonuclease protection assay (RPA) to quantify rat TRPV1, TRPV2, TRPV3, TRPV4, TRPA1, and TRPM8 RNA levels in DRG. We used the multiplex RPA to measure thermosensitive TRP channel RNA levels in DRG from RTX-treated rats (300 microg/kg) or rats with unilateral sciatic nerve chronic constriction injury (CCI). TRPV1 and TRPA1 RNA were significantly decreased in DRG from RTX-treated rats, indicating functional colocalization of TRPA1 and TRPV1 in sensory nociceptors. In DRG from CCI rats, TRPA1, TRPV2, and TRPM8 RNA showed slight but significant increases ipsilateral to peripheral nerve injury. Our findings support the hypothesis that increased TRP channel expression in sensory neurons may contribute to mechanical and cold hypersensitivity.
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Affiliation(s)
- J Frederick
- Western Connecticut State University, 181 White Street, Danbury, CT 06810, USA.
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570
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Kosugi M, Nakatsuka T, Fujita T, Kuroda Y, Kumamoto E. Activation of TRPA1 channel facilitates excitatory synaptic transmission in substantia gelatinosa neurons of the adult rat spinal cord. J Neurosci 2007; 27:4443-51. [PMID: 17442829 PMCID: PMC6672326 DOI: 10.1523/jneurosci.0557-07.2007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
TRPA1 is expressed in primary sensory neurons and hair cells, and it is proposed to be activated by cold stimuli, mechanical stimuli, or pungent ingredients. However, its role in regulating synaptic transmission has never been documented yet. In the present study, we examined whether activation of the TRPA1 channels affects synaptic transmission in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. A chief ingredient of mustard oil, allyl isothiocyanate (AITC), superfused for 2 min markedly increased the frequency and amplitude of spontaneous EPSCs (sEPSCs), which was accompanied by an inward current. Similar actions were produced by cinnamaldehyde and allicin. The AITC-induced increases in sEPSC frequency and amplitude were resistant to tetrodotoxin (TTX) and La3+, whereas being significantly reduced in extent in a Ca2+-free bath solution. In the presence of glutamate receptor antagonists CNQX and AP5, AITC did not generate any synaptic activities. The AITC-induced increases in sEPSC frequency and amplitude were reduced by ruthenium red, whereas being unaffected by capsazepine. AITC also increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents; this AITC action was abolished in the presence of TTX or glutamate receptor antagonists. These results indicate that TRPA1 appears to be localized not only at presynaptic terminals on SG neurons to enhance glutamate release, but also in terminals of primary afferents innervating onto spinal inhibitory interneurons, which make synapses with SG neurons. This central modulation of sensory signals may be associated with physiological and pathological pain sensations.
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Affiliation(s)
- Masafumi Kosugi
- Departments of Physiology and
- Neurology, Faculty of Medicine, Saga University, Saga 849-8501, Japan
| | | | | | - Yasuo Kuroda
- Neurology, Faculty of Medicine, Saga University, Saga 849-8501, Japan
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571
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Paré M, Albrecht PJ, Noto CJ, Bodkin NL, Pittenger GL, Schreyer DJ, Tigno XT, Hansen BC, Rice FL. Differential hypertrophy and atrophy among all types of cutaneous innervation in the glabrous skin of the monkey hand during aging and naturally occurring type 2 diabetes. J Comp Neurol 2007; 501:543-67. [PMID: 17278131 DOI: 10.1002/cne.21262] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diabetic neuropathy (DN) is a common severe complication of type 2 diabetes. The symptoms of chronic pain, tingling, and numbness are generally attributed to small fiber dysfunction. However, little is known about the pathology among innervation to distal extremities, where symptoms start earliest and are most severe, and where the innervation density is the highest and includes a wide variety of large fiber sensory endings. Our study assessed the immunochemistry, morphology, and density of the nonvascular innervation in glabrous skin from the hands of aged nondiabetic rhesus monkeys and from age-matched monkeys that had different durations of spontaneously occurring type 2 diabetes. Age-related reductions occurred among all types of innervation, with epidermal C-fiber endings preferentially diminishing earlier than presumptive Adelta-fiber endings. In diabetic monkeys epidermal innervation density diminished faster, became more unevenly distributed, and lost immunodetectable expression of calcitonin gene-related peptide and capsaicin receptors, TrpV1. Pacinian corpuscles also deteriorated. However, during the first few years of hyperglycemia, a surprising hypertrophy occurred among terminal arbors of remaining epidermal endings. Hypertrophy also occurred among Meissner corpuscles and Merkel endings supplied by Abeta fibers. After longer-term hyperglycemia, Meissner corpuscle hypertrophy declined but the number of corpuscles remained higher than in age-matched nondiabetics. However, the diabetic Meissner corpuscles had an abnormal structure and immunochemistry. In contrast, the expanded Merkel innervation was reduced to age-matched nondiabetic levels. These results indicate that transient phases of substantial innervation remodeling occur during the progression of diabetes, with differential increases and decreases occurring among the varieties of innervation.
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Affiliation(s)
- Michel Paré
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York 12208, USA
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572
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Szallasi A, Cortright DN, Blum CA, Eid SR. The vanilloid receptor TRPV1: 10 years from channel cloning to antagonist proof-of-concept. Nat Rev Drug Discov 2007; 6:357-72. [PMID: 17464295 DOI: 10.1038/nrd2280] [Citation(s) in RCA: 627] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The clinical use of TRPV1 (transient receptor potential vanilloid subfamily, member 1; also known as VR1) antagonists is based on the concept that endogenous agonists acting on TRPV1 might provide a major contribution to certain pain conditions. Indeed, a number of small-molecule TRPV1 antagonists are already undergoing Phase I/II clinical trials for the indications of chronic inflammatory pain and migraine. Moreover, animal models suggest a therapeutic value for TRPV1 antagonists in the treatment of other types of pain, including pain from cancer. We argue that TRPV1 antagonists alone or in conjunction with other analgesics will improve the quality of life of people with migraine, chronic intractable pain secondary to cancer, AIDS or diabetes. Moreover, emerging data indicate that TRPV1 antagonists could also be useful in treating disorders other than pain, such as urinary urge incontinence, chronic cough and irritable bowel syndrome. The lack of effective drugs for treating many of these conditions highlights the need for further investigation into the therapeutic potential of TRPV1 antagonists.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology, Monmouth Medical Center, Long Branch, New Jersey 07740, USA.
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573
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Li BY, Schild JH. Electrophysiological and pharmacological validation of vagal afferent fiber type of neurons enzymatically isolated from rat nodose ganglia. J Neurosci Methods 2007; 164:75-85. [PMID: 17512602 PMCID: PMC2003207 DOI: 10.1016/j.jneumeth.2007.04.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 03/26/2007] [Accepted: 04/02/2007] [Indexed: 11/26/2022]
Abstract
An unavoidable consequence of enzymatic dispersion of sensory neurons from intact ganglia is loss of the axon and thus the ability to classify afferent fiber type based upon conduction velocity (CV). An intact rat nodose ganglion preparation was used to randomly sample neurons (n=76) using the patch clamp technique. Reliable electrophysiological and chemophysiological correlates of afferent fiber type were established for use with isolated neuron preparations. Myelinated afferents (approximately 25%) formed two groups exhibiting strikingly different functional profiles. One group (n=10) exhibited CVs in excess of 10 m/s and narrow (<1 ms) action potentials (APs) while the other (n=9) had CVs as low as 4m/s and broad (>2 ms) APs that closely approximated those identified as unmyelinated afferents (n=57) with CVs less than 1m/s. A cluster analysis of select measures from the AP waveforms strongly correlated with CV, producing three statistically unique populations (p<0.05). These groupings aligned with our earlier hypothesis (Jin et al., 2004) that a differential sensitivity to the selective purinergic and vanilloid receptor agonists can be used as reliable pharmacological indicators of vagal afferent fiber type. These metrics were further validated using an even larger population of isolated (n=240) nodose neurons. Collectively, these indicators of afferent fiber type can be used to provide valuable insight concerning the relavence of isolated cellular observations to integrated afferent function of visceral organ systems.
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Affiliation(s)
- Bai-Yan Li
- Dept. of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202
- Dept. of Pharmacology, Harbin Medical University, Harbin, 150081, CHINA
| | - John H Schild
- Dept. of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202
- *Corresponding author Address: 723 W. Michigan St., Suite SL174, Indianapolis, IN 46202, E-mail: (J.H. Schild). Phone: 317-274-9747
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574
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Hjerling-Leffler J, AlQatari M, Ernfors P, Koltzenburg M. Emergence of functional sensory subtypes as defined by transient receptor potential channel expression. J Neurosci 2007; 27:2435-43. [PMID: 17344381 PMCID: PMC6672507 DOI: 10.1523/jneurosci.5614-06.2007] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2006] [Revised: 01/16/2007] [Accepted: 01/17/2007] [Indexed: 01/01/2023] Open
Abstract
The existence of heterogeneous populations of dorsal root ganglion (DRG) neurons conveying different somatosensory information is the basis for the perception of touch, temperature, and pain. A differential expression of transient receptor potential (TRP) cation channels contributes to this functional heterogeneity. However, little is known about the development of functionally diverse neuronal subpopulations. Here, we use calcium imaging of acutely dissociated mouse sensory neurons and quantitative reverse transcription PCR to show that TRP cation channels emerge in waves, with the diversification of functional groups starting at embryonic day 12.5 (E12.5) and extending well into the postnatal life. Functional responses of voltage-gated calcium channels were present in DRG neurons at E11.5 and reached adult levels by E14.5. Responses to capsaicin, menthol, and cinnamaldehyde were first seen at E12.5, E16.5, and postnatal day 0 (P0), when the mRNA for TRP cation channel, subfamily V, member 1 (TRPV1), TRP cation channel, subfamily M, member 8 (TRPM8), and TRP cation channel, subfamily A, member 1 (TRPA1), respectively, was first detected. Cold-sensitive neurons were present before the expression or functional responses of TRPM8 or TRPA1. Our data support a lineage relationship in which TRPM8- and TRPA1-expressing sensory neurons derive from the population of TRPV1-expressing neurons. The TRPA1 subpopulation of neurons emerges independently in two distinct classes of nociceptors: around birth in the peptidergic population and after P14 in the nonpeptidergic class. This indicates that neurons with similar receptive properties can be generated in different sublineages at different developmental stages. This study describes for the first time the emergence of functional subtypes of sensory neurons, providing new insight into the development of nociception and thermoreception.
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MESH Headings
- Acrolein/analogs & derivatives
- Acrolein/pharmacology
- Aging/metabolism
- Animals
- Animals, Newborn
- Calcium Channels/metabolism
- Capsaicin/pharmacology
- Cell Differentiation
- Cell Lineage
- Cells, Cultured
- Cold Temperature
- Embryo, Mammalian
- Embryonic Development
- Ganglia, Spinal/cytology
- Ganglia, Spinal/embryology
- Ganglia, Spinal/metabolism
- Menthol/pharmacology
- Mice
- Mice, Inbred C57BL
- Neurons, Afferent/classification
- Neurons, Afferent/cytology
- Neurons, Afferent/metabolism
- Neurons, Afferent/physiology
- Nociceptors/physiology
- Plant Lectins/pharmacokinetics
- RNA, Messenger/metabolism
- TRPA1 Cation Channel
- TRPM Cation Channels/genetics
- TRPV Cation Channels/genetics
- Thermoreceptors/physiology
- Transient Receptor Potential Channels/agonists
- Transient Receptor Potential Channels/genetics
- Transient Receptor Potential Channels/metabolism
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Affiliation(s)
- Jens Hjerling-Leffler
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden, and
- University College London Institute of Child Health, University College London, London WC1N 1EH, United Kingdom
| | - Mona AlQatari
- University College London Institute of Child Health, University College London, London WC1N 1EH, United Kingdom
| | - Patrik Ernfors
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden, and
| | - Martin Koltzenburg
- University College London Institute of Child Health, University College London, London WC1N 1EH, United Kingdom
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575
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Abstract
In this article, we review the key basic mechanisms associated with this phenomena and more recently identified mechanisms that are current areas of interest. Although many of these pain mechanisms apply throughout the body, we attempt to describe these mechanisms in the context of trigeminal pain.
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Affiliation(s)
- Michael A Henry
- Department of Endodontics, University of Texas Health Science Center at San Antonio School of Dentistry, Mail Code 7892, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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576
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Mazarío J, Basbaum AI. Contribution of substance P and neurokinin A to the differential injury-induced thermal and mechanical responsiveness of lamina I and V neurons. J Neurosci 2007; 27:762-70. [PMID: 17251415 PMCID: PMC6672913 DOI: 10.1523/jneurosci.2992-06.2007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In a previous report, we compared the properties of lamina V neurons of the spinal cord dorsal horn in wild-type mice and in mice with a deletion of the preprotachykinin-A (PPT-A) gene, which encodes substance P (SP) and neurokinin A (NKA). The mutant mice had pronounced deficits in the response to thermal stimulation, both before and after mustard oil induced sensitization. Here, we extended our analysis to the properties of lamina I neurons and also examined responsiveness to mechanical stimulation. Consistent with the properties of lamina V neurons, in the PPT-A mutant mice we found significantly reduced responses of lamina I neurons to noxious thermal stimulation, and mustard oil sensitization of these neurons to heat was lost. In contrast, not only were the responses of lamina I neurons to noxious mechanical stimulation unchanged in the mutant mice, but in neither the wild-type nor the mutant mice could sensitization be induced. However, mustard oil profoundly sensitized lamina V neurons to mechanical stimulation in both wild-type and mutant mice. We conclude that SP and/or NKA are required for the transmission of noxious thermal stimulation by lamina I and V neurons, both before and after tissue injury. The persistence of mechanical sensitization of lamina V neurons in the mutant mice further shows that mustard oil induces mechanical and thermal sensitization through different mechanisms. Finally, we conclude that lamina I sensitization to mechanical stimulation is not required for this form of injury-increased responsiveness of lamina V neurons.
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Affiliation(s)
- Javier Mazarío
- Laboratorio de Función Sensitivomotora, Hospital Nacional de Parapléjicos, 45071 Toledo, Spain.
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577
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Zanotto KL, Merrill AW, Carstens MI, Carstens E. Neurons in Superficial Trigeminal Subnucleus Caudalis Responsive to Oral Cooling, Menthol, and Other Irritant Stimuli. J Neurophysiol 2007; 97:966-78. [PMID: 17151223 DOI: 10.1152/jn.00996.2006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The recent discoveries of cold-sensitive transient receptor potential (TRP) channels prompted us to investigate the responses of neurons in trigeminal subnucleus caudalis (Vc) to intraoral cooling and agonists of TRPM8 and TRPA1. Single units responsive to lingual cooling were recorded in superficial laminae of Vc in thiopental-anesthetized rats. All units responded to noxious heat and 88% responded to menthol. Responses increased with menthol concentration from 0.1 to 1% (6.4–64 mM) and plateaued at 10% (640 mM). Noxious cold-evoked responses were significantly enhanced after menthol in a concentration-dependent manner. Constant-flow application of 1% menthol elicited a phasic discharge that adapted over 2–8 min and significantly enhanced subsequent cold-evoked but not heat-evoked responses; vehicle (10% ethanol) was ineffective. Reapplication of menthol 15 min later elicited a significantly reduced response (self-desensitization). Vc units were similarly excited phasically by 1% menthol dissolved in 40% ethanol. The 40% ethanol briefly excited Vc units during the first minute and reduced subsequent responses to noxious heat and cold while exhibiting neither self-desensitization nor cross-desensitization to menthol. Menthol cross-desensitized Vc responses to 40% ethanol. Most menthol-responsive units also responded to the TRPA1 agonists cinnamaldehyde and mustard oil, and the TRPV1 agonist capsaicin. Units in superficial Vc receive convergent input from primary afferents that express TRPM8, TRPA1, and/or TRPV1 channels, either directly or indirectly via intersubnuclear pathways. The convergent nature of these units suggests a general role in signaling noxious stimuli.
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Affiliation(s)
- Karen L Zanotto
- Section of Neurobiology, Physiology and Behavior, University of California-Davis, 1 Shields Ave., Davis, CA 95616, USA
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578
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Coste B, Crest M, Delmas P. Pharmacological dissection and distribution of NaN/Nav1.9, T-type Ca2+ currents, and mechanically activated cation currents in different populations of DRG neurons. J Gen Physiol 2007; 129:57-77. [PMID: 17190903 PMCID: PMC2151607 DOI: 10.1085/jgp.200609665] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Accepted: 12/04/2006] [Indexed: 02/04/2023] Open
Abstract
Low voltage-activated (LVA) T-type Ca(2+) (I(Ca)T) and NaN/Nav1.9 currents regulate DRG neurons by setting the threshold for the action potential. Although alterations in these channels have been implicated in a variety of pathological pain states, their roles in processing sensory information remain poorly understood. Here, we carried out a detailed characterization of LVA currents in DRG neurons by using a method for better separation of NaN/Nav1.9 and I(Ca)T currents. NaN/Nav1.9 was inhibited by inorganic I(Ca) blockers as follows (IC(50), microM): La(3+) (46) > Cd(2+) (233) > Ni(2+) (892) and by mibefradil, a non-dihydropyridine I(Ca)T antagonist. Amiloride, however, a preferential Cav3.2 channel blocker, had no effects on NaN/Nav1.9 current. Using these discriminative tools, we showed that NaN/Nav1.9, Cav3.2, and amiloride- and Ni(2+)-resistant I(Ca)T (AR-I(Ca)T) contribute differentially to LVA currents in distinct sensory cell populations. NaN/Nav1.9 carried LVA currents into type-I (CI) and type-II (CII) small nociceptors and medium-Adelta-like nociceptive cells but not in low-threshold mechanoreceptors, including putative Down-hair (D-hair) and Aalpha/beta cells. Cav3.2 predominated in CII-nociceptors and in putative D-hair cells. AR-I(Ca)T was restricted to CII-nociceptors, putative D-hair cells, and Aalpha/beta-like cells. These cell types distinguished by their current-signature displayed different types of mechanosensitive channels. CI- and CII-nociceptors displayed amiloride-sensitive high-threshold mechanical currents with slow or no adaptation, respectively. Putative D-hair and Aalpha/beta-like cells had low-threshold mechanical currents, which were distinguished by their adapting kinetics and sensitivity to amiloride. Thus, subspecialized DRG cells express specific combinations of LVA and mechanosensitive channels, which are likely to play a key role in shaping responses of DRG neurons transmitting different sensory modalities.
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Affiliation(s)
- Bertrand Coste
- Laboratoire de Neurophysiologie Cellulaire, Centre National de la Recherche Scientifique, UMR 6150, Faculté de Médecine, IFR Jean Roche, 13916 Marseille Cedex 20, France
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579
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Abstract
The TRPA1 protein has up to 18 N-terminal and presumed cytoplasmic ankyrin repeats followed by the six membrane spanning and single pore-loop domains characteristic of all TRPs. In mice, TRPA1 is almost exclusively expressed in nociceptive neurons of peripheral ganglia and in all the mechanosensory epithelia of inner ear. In nociceptive neurons, TRPA1 mediates the response to the proalgesic bradykinin as well as the response to pungent irritants found in mustards and garlic, and probably also to those found in cinnamon and tear gas. The channel properties of TRPA1 are discussed and compared to those of sensory transducers. TRPA1 is well conserved across the animal kingdom, with likely orthologs from human to nematode, which suggest an ancestral role for this channel, probably in sensation.
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Affiliation(s)
- J García-Añoveros
- Department of Anesthesiology, Northwestern University Institute for Neuroscience, Feinberg School of Medicine, Ward 10-070, 303 E Chicago Ave., Chicago, IL 60611, USA.
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580
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MechanoTRPs and TRPA1. CURRENT TOPICS IN MEMBRANES 2007. [PMID: 25168138 DOI: 10.1016/s1063-5823(06)59008-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Genetic and molecular searches in animals identify two families of ion channels used by specialized mechanosensory cells. These are the degenerin/epithelial Na+ channels (Deg/ENaCs) and transient receptor potential (TRP) channels. Some of these channels open in response to mechanical forces and/or mediate cellular responses to mechanical stimulation. TRPA1 is expressed in nociceptive neurons of peripheral ganglia and in the sensory epithelia of the inner ear. In nociceptors, TRPA1 forms chemosensitive channels that mediate the response to exogenous pain-producing chemicals as well as to the endogenous proalgesic bradykinin (BK). More indirect evidence suggests that TRPA1 might also form mechanosensory channels. Some of the TRP channels that mediate mechanical responses are not necessarily mechanically gated. For example, TRPV4 mutant mice have reduced sensitivity to noxious tactile stimulation, and heterologously expressed TRPV4 opens in response to hypotonic solution (which induces cell swelling and thus stretches membranes). TRPA1 genes in mammals are large, occupy around 50kb of chromosomal DNA and are encoded by at least 27 exons. In humans, the TRPA1 gene is located on chromosome 8q13.
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581
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Rossi HL, Vierck CJ, Caudle RM, Neubert JK. Characterization of cold sensitivity and thermal preference using an operant orofacial assay. Mol Pain 2006; 2:37. [PMID: 17166284 PMCID: PMC1764875 DOI: 10.1186/1744-8069-2-37] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 12/13/2006] [Indexed: 11/29/2022] Open
Abstract
Background A hallmark of many orofacial pain disorders is cold sensitivity, but relative to heat-related pain, mechanisms of cold perception and the development of cold allodynia are not clearly understood. Molecular mediators of cold sensation such as TRPM8 have been recently identified and characterized using in vitro studies. In this study we characterized operant behavior with respect to individually presented cold stimuli (24, 10, 2, and -4°C) and in a thermal preference task where rats chose between -4 and 48°C stimulation. We also evaluated the effects of menthol, a TRPM8 agonist, on operant responses to cold stimulation (24, 10, and -4°C). Male and female rats were trained to drink sweetened milk while pressing their shaved faces against a thermode. This presents a conflict paradigm between milk reward and thermal stimulation. Results We demonstrated that the cold stimulus response function was modest compared to heat. There was a significant effect of temperature on facial (stimulus) contacts, the ratio of licking contacts to stimulus contacts, and the stimulus duration/contact ratio. Males and females differed only in their facial contacts at 10°C. In the preference task, males preferred 48°C to -4°C, despite the fact that 48°C and -4°C were equally painful as based on their reward/stimulus and duration/contact ratios. We were able to induce hypersensitivity to cold using menthol at 10°C, but not at 24 or -4°C. Conclusion Our results indicate a strong role for an affective component in processing of cold stimuli, more so than for heat, which is in concordance with human psychophysical findings. The induction of allodynia with menthol provides a model for cold allodynia. This study provides the basis for future studies involving orofacial pain and analgesics, and is translatable to the human experience.
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Affiliation(s)
- Heather L Rossi
- College of Dentistry Department of Orthodontics, University of Florida, 1600 S.W. Archer Road, P.O. Box 100444, Gainesville, FL 32610-0444, USA
| | - Charles J Vierck
- College of Medicine Department of Neuroscience, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
- Evelyn F. and William L. McKnight Brain Institute, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
| | - Robert M Caudle
- College of Dentistry Department of Oral Surgery, University of Florida, 1600 S.W. Archer Road, P.O. Box 100416, Gainesville, FL 32610-0444, USA
- College of Medicine Department of Neuroscience, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
- Evelyn F. and William L. McKnight Brain Institute, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
| | - John K Neubert
- College of Dentistry Department of Orthodontics, University of Florida, 1600 S.W. Archer Road, P.O. Box 100444, Gainesville, FL 32610-0444, USA
- College of Medicine Department of Neuroscience, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
- Evelyn F. and William L. McKnight Brain Institute, University of Florida, 100 Newell DR., P.O. Box 100015, Gainesville, FL 32610-0444, USA
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582
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Proudfoot CJ, Garry EM, Cottrell DF, Rosie R, Anderson H, Robertson DC, Fleetwood-Walker SM, Mitchell R. Analgesia mediated by the TRPM8 cold receptor in chronic neuropathic pain. Curr Biol 2006; 16:1591-605. [PMID: 16920620 DOI: 10.1016/j.cub.2006.07.061] [Citation(s) in RCA: 300] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 07/11/2006] [Accepted: 07/21/2006] [Indexed: 01/27/2023]
Abstract
BACKGROUND Chronic established pain, especially that following nerve injury, is difficult to treat and represents a largely unmet therapeutic need. New insights are urgently required, and we reasoned that endogenous processes such as cooling-induced analgesia may point the way to novel strategies for intervention. Molecular receptors for cooling have been identified in sensory nerves, and we demonstrate here how activation of one of these, TRPM8, produces profound, mechanistically novel analgesia in chronic pain states. RESULTS We show that activation of TRPM8 in a subpopulation of sensory afferents (by either cutaneous or intrathecal application of specific pharmacological agents or by modest cooling) elicits analgesia in neuropathic and other chronic pain models in rats, thereby inhibiting the characteristic sensitization of dorsal-horn neurons and behavioral-reflex facilitation. TRPM8 expression was increased in a subset of sensory neurons after nerve injury. The essential role of TRPM8 in suppression of sensitized pain responses was corroborated by specific knockdown of its expression after intrathecal application of an antisense oligonucleotide. We further show that the analgesic effect of TRPM8 activation is centrally mediated and relies on Group II/III metabotropic glutamate receptors (mGluRs), but not opioid receptors. We propose a scheme in which Group II/III mGluRs would respond to glutamate released from TRPM8-containing afferents to exert an inhibitory gate control over nociceptive inputs. CONCLUSIONS TRPM8 and its central downstream mediators, as elements of endogenous-cooling-induced analgesia, represent a novel analgesic axis that can be exploited in chronic sensitized pain states.
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Affiliation(s)
- Clare J Proudfoot
- Centre for Neuroscience Research, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, United Kingdom
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583
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Green BG, Schoen KL. Thermal and nociceptive sensations from menthol and their suppression by dynamic contact. Behav Brain Res 2006; 176:284-91. [PMID: 17092576 PMCID: PMC1861819 DOI: 10.1016/j.bbr.2006.10.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 07/07/2006] [Accepted: 10/11/2006] [Indexed: 01/25/2023]
Abstract
It was recently found that cooling the skin to temperatures as mild as 25-30 degrees C can induce nociceptive sensations (burning, stinging or pricking) that are strongly suppressed by dynamic contact between the thermode and skin (contact suppression). Here we investigated whether nociceptive sensations produced by menthol can be similarly suppressed. In the first experiment subjects rated the intensity of cold and burning/stinging/pricking sensations before and after application of 10% l-menthol to the forearm. Ratings were compared at resting skin temperature ( approximately 33 degrees C) and at 28, 24, or 20 degrees C during static or dynamic contact cooling via a Peltier thermode. At resting skin temperature, menthol produced cold and nociceptive sensations, both of which were suppressed by dynamic contact. When the skin was cooled during static contact, menthol increased nociceptive sensations but not cold sensations; when the skin was cooled during dynamic contact, cold sensations were again unchanged while nociceptive sensations were suppressed. A second experiment tested whether contact suppression of menthol's cold and nociceptive sensations at resting skin temperature was caused by slight deviations of thermode temperature above skin temperature. The results showed that suppression occurred even when the thermode was slightly cooler (-0.5 degrees C) than the skin. These findings support other evidence that the menthol-sensitive channel, TRPM8, plays a role in cold nociception, and raise new questions about how dynamic tactile stimulation may modify perception of nonpainful cold stimulation.
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Affiliation(s)
- Barry G Green
- The John B. Pierce Laboratory, United States; Department of Surgery (Otolaryngology), Yale University School of Medicine, United States.
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584
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Abstract
The neurobiology of itch, which is formally known as pruritus, and its interaction with pain have been illustrated by the complexity of specific mediators, itch-related neuronal pathways and the central processing of itch. Scratch-induced pain can abolish itch, and analgesic opioids can generate itch, which indicates an antagonistic interaction. However, recent data suggest that there is a broad overlap between pain- and itch-related peripheral mediators and/or receptors, and there are astonishingly similar mechanisms of neuronal sensitization in the PNS and the CNS. The antagonistic interaction between pain and itch is already exploited in pruritus therapy, and current research concentrates on the identification of common targets for future analgesic and antipruritic therapy.
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Affiliation(s)
- Akihiko Ikoma
- Department of Dermatology, Kyoto University, Shogin-Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan
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585
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Bautista DM, Jordt SE, Nikai T, Tsuruda PR, Read AJ, Poblete J, Yamoah EN, Basbaum AI, Julius D. TRPA1 mediates the inflammatory actions of environmental irritants and proalgesic agents. Cell 2006; 124:1269-82. [PMID: 16564016 DOI: 10.1016/j.cell.2006.02.023] [Citation(s) in RCA: 1425] [Impact Index Per Article: 79.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 01/06/2006] [Accepted: 02/08/2006] [Indexed: 12/20/2022]
Abstract
TRPA1 is an excitatory ion channel targeted by pungent irritants from mustard and garlic. TRPA1 has been proposed to function in diverse sensory processes, including thermal (cold) nociception, hearing, and inflammatory pain. Using TRPA1-deficient mice, we now show that this channel is the sole target through which mustard oil and garlic activate primary afferent nociceptors to produce inflammatory pain. TRPA1 is also targeted by environmental irritants, such as acrolein, that account for toxic and inflammatory actions of tear gas, vehicle exhaust, and metabolic byproducts of chemotherapeutic agents. TRPA1-deficient mice display normal cold sensitivity and unimpaired auditory function, suggesting that this channel is not required for the initial detection of noxious cold or sound. However, TRPA1-deficient mice exhibit pronounced deficits in bradykinin-evoked nociceptor excitation and pain hypersensitivity. Thus, TRPA1 is an important component of the transduction machinery through which environmental irritants and endogenous proalgesic agents depolarize nociceptors to elicit inflammatory pain.
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Affiliation(s)
- Diana M Bautista
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
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586
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Tominaga M. [TRP channels and nociception]. Nihon Yakurigaku Zasshi 2006; 127:128-32. [PMID: 16651789 DOI: 10.1254/fpj.127.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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587
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Kwan KY, Allchorne AJ, Vollrath MA, Christensen AP, Zhang DS, Woolf CJ, Corey DP. TRPA1 Contributes to Cold, Mechanical, and Chemical Nociception but Is Not Essential for Hair-Cell Transduction. Neuron 2006; 50:277-89. [PMID: 16630838 DOI: 10.1016/j.neuron.2006.03.042] [Citation(s) in RCA: 971] [Impact Index Per Article: 53.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 02/23/2006] [Accepted: 03/31/2006] [Indexed: 10/24/2022]
Abstract
TRPA1, a member of the transient receptor potential (TRP) family of ion channels, is expressed by dorsal root ganglion neurons and by cells of the inner ear, where it has proposed roles in sensing sound, painful cold, and irritating chemicals. To test the in vivo roles of TRPA1, we generated a mouse in which the essential exons required for proper function of the Trpa1 gene were deleted. Knockout mice display behavioral deficits in response to mustard oil, to cold ( approximately 0 degrees C), and to punctate mechanical stimuli. These mice have a normal startle reflex to loud noise, a normal sense of balance, a normal auditory brainstem response, and normal transduction currents in vestibular hair cells. TRPA1 is apparently not essential for hair-cell transduction but contributes to the transduction of mechanical, cold, and chemical stimuli in nociceptor sensory neurons.
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Affiliation(s)
- Kelvin Y Kwan
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
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588
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Katsura H, Obata K, Mizushima T, Yamanaka H, Kobayashi K, Dai Y, Fukuoka T, Tokunaga A, Sakagami M, Noguchi K. Antisense knock down of TRPA1, but not TRPM8, alleviates cold hyperalgesia after spinal nerve ligation in rats. Exp Neurol 2006; 200:112-23. [PMID: 16546170 DOI: 10.1016/j.expneurol.2006.01.031] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 01/18/2006] [Accepted: 01/20/2006] [Indexed: 02/02/2023]
Abstract
Patients with neuropathic pain frequently experience hypersensitivity to cold stimulation. However, the underlying mechanisms of this enhanced sensitivity to cold are not well understood. After partial nerve injury, the transient receptor potential ion channel TRPV1 increases in the intact small dorsal root ganglion (DRG) neurons in several neuropathic pain models. In the present study, we precisely examined the incidence of cold hyperalgesia and the changes of TRPA1 and TRPM8 expression in the L4 and L5 DRG following L5 spinal nerve ligation (SNL), because it is likely that the activation of two distinct populations of TRPA1- and TRPM8-expressing small neurons underlie the sensation of cold. We first confirmed that L5 SNL rats developed cold hyperalgesia for more than 14 days after surgery. In the nearby uninjured L4 DRG, TRPA1 mRNA expression increased in trkA-expressing small-to-medium diameter neurons from the 1st to 14th day after the L5 SNL. This upregulation corresponded well with the development and maintenance of nerve injury-induced cold hyperalgesia of the hind paw. In contrast, there was no change in the expression of the TRPM8 mRNA/protein in the L4 DRG throughout the 2-week time course of the experiment. In the injured L5 DRG, on the other hand, both TRPA1 and TRPM8 expression decreased over 2 weeks after ligation. Furthermore, intrathecal administration of TRPA1, but not TRPM8, antisense oligodeoxynucleotide suppressed the L5 SNL-induced cold hyperalgesia. Our data suggest that increased TRPA1 in uninjured primary afferent neurons may contribute to the exaggerated response to cold observed in the neuropathic pain model.
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Affiliation(s)
- Hirokazu Katsura
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
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589
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Mizushima T, Obata K, Katsura H, Yamanaka H, Kobayashi K, Dai Y, Fukuoka T, Tokunaga A, Mashimo T, Noguchi K. Noxious cold stimulation induces mitogen-activated protein kinase activation in transient receptor potential (TRP) channels TRPA1- and TRPM8-containing small sensory neurons. Neuroscience 2006; 140:1337-48. [PMID: 16675144 DOI: 10.1016/j.neuroscience.2006.03.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 03/10/2006] [Accepted: 03/14/2006] [Indexed: 01/09/2023]
Abstract
Two cold-sensitive transient receptor potential (TRP) channels, TRPA1 and TRPM8, have been identified and considered interesting because of their possible roles in thermosensation, nociception and other functions. Recently, we have reported that the phosphorylation of extracellular signal-regulated protein kinase and p38 mitogen-activated protein kinase occurred in primary afferent neurons in response to noxious heat stimulation of the peripheral tissue, i.e. activity-dependent activation of extracellular signal-regulated protein kinase and p38 in dorsal root ganglion neurons. In the present study, we investigated the phosphorylation of extracellular signal-regulated protein kinase, p38, and c-Jun N-terminal kinase in the rat dorsal root ganglion by cold stimulation using immunohistochemistry. Cold stimuli (28-4 degrees C) were applied by immersion of the hind paw into a water bath (six times of 10 s stimulation and 10 s interval, total 2 min). Noxious cold stimulation induced phosphorylated-extracellular signal-regulated protein kinase and phosphorylated-p38, but not phosphorylated-c-Jun N-terminal kinase, in small to medium diameter sensory neurons with a peak at 2 min after stimulation. We found that a cold stimulation at 4 degrees C showed a marked increase in the number of activated neurons. Furthermore, double staining for phosphorylated-extracellular signal-regulated protein kinase and phosphorylated-p38 showed no colocalization in the dorsal root ganglion neurons. We then performed double-labeling experiments for TRPA1 and TRPM8 mRNA and phosphorylation of mitogen-activated protein kinase. The majority of phosphorylated-extracellular signal-regulated protein kinase-positive neurons also expressed TRPM8 mRNA, whereas phosphorylated-p38 heavily colocalized with TRPA1 mRNA after noxious cold stimulation. Our data suggest that the noxious, but not innocuous, cold stimulation in vivo induced differential activation of extracellular signal-regulated protein kinase and p38 pathways in each subpopulation containing TRPA1 or TRPM8 in dorsal root ganglion.
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Affiliation(s)
- T Mizushima
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
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590
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Fukuoka T, Noguchi K. Chapter 15 Expression Patterns and Histological Aspects of TRP Channels in Sensory Neurons. CURRENT TOPICS IN MEMBRANES 2006. [DOI: 10.1016/s1063-5823(06)57014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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591
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Bécouarn Y, Ychou M, Ducreux M, Borel C, Bertheault-Cvitkovic F, Seitz JF, Nasca S, Nguyen TD, Paillot B, Raoul JL, Duffour J, Fandi A, Dupont-André G, Rougier P. Phase II trial of oxaliplatin as first-line chemotherapy in metastatic colorectal cancer patients. Digestive Group of French Federation of Cancer Centers. J Clin Oncol 1998; 7:29. [PMID: 21521528 PMCID: PMC3105941 DOI: 10.1186/1744-8069-7-29] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 04/26/2011] [Indexed: 01/23/2023] Open
Abstract
PURPOSE To evaluate the objective tumor response rate and safety profile of oxaliplatin when administered to patients with previously untreated metastatic colorectal adenocarcinoma. PATIENTS AND METHODS A total of 39 patients were entered onto this phase II trial. One patient was excluded for having had a second cancer, so the study was based on 38 patients. Patients were treated with oxaliplatin 130 mg/m2 as a 2-hour infusion on day 1, every 21 days. Patients were assessed for response every three courses. All clinical and radiologic data were reviewed by an external panel of experts, with their assessment being considered definitive. RESULTS Nine partial responses (PRs) were observed (response rate, 24.3%; 95% confidence interval, 11.8% to 41.2%). The median duration of response was 216+ days. Fifteen patients (40.5%) had stable disease and 13 (35.2%) had progressive disease. The median progression-free survival time for all patients was 126+ days (range, 21 to 447+). The main toxicity was peripheral sensory neuropathy. Grade 3 neurotoxicity (National Cancer Institute common toxicity criteria [NCI-CTC]) was reported in 13%. Hematologic and gastrointestinal toxicities were mild. The incidence of grade 3 neutropenia was 5.2%, while that of grade 3 or 4 thrombopenia was 7.9%. Vomiting (grade 3 or 4) occurred in 7.9% of patients and grade 3 diarrhea in 2.6%. CONCLUSION This phase II study provides clear evidence of the safety and efficacy of oxaliplatin monotherapy at this dose and schedule in patients with previously untreated metastatic colorectal carcinoma.
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