101
|
Abstract
In psychophysical experiments, humans use different verbal responses to pruritic and algesic chemical stimuli to indicate the different qualities of sensation they feel. A major challenge for behavioural models in the mouse of chemical itch and pain in humans is to devise experimental protocols that provide the opportunity for the animal to exhibit a multiplicity of responses as well. One basic criterion is that chemicals that evoke primarily itch or pain in humans should elicit different types of responses when applied in the same way to the mouse. Meeting this criterion is complicated by the fact that the type of behavioural responses exhibited by the mouse depends in part on the site of chemical application such as the nape of the neck that evokes only scratching with the hind paw versus the hind limb that elicits licking and biting. Here, we review to what extent mice behaviourally differentiate chemicals that elicit itch versus pain in humans.
Collapse
Affiliation(s)
- Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.
| | | | | |
Collapse
|
102
|
Abstract
Itch is a major somatic sensation, along with pain, temperature, and touch, detected and relayed by the somatosensory system. Itch can be an acute sensation, associated with mosquito bite, or a chronic condition, like atopic dermatitis (29, 59). The origins of the stimulus can be localized in the periphery or systemic, and associated with organ failure or cancer. Itch is also a perception originating in the brain. Itch is broadly characterized as either histamine-dependent (histaminergic) or histamine-independent (nonhistaminergic), both of which are relayed by subsets of C fibers and by the second-order neurons expressing gastrin-releasing peptide receptor (GRPR) and spinothalamic track (STT) neurons in the spinal cord of rodents. Historically, itch research has been primarily limited to clinical and psychophysical studies and to histamine-mediated mechanisms. In contrast, little is known about the signaling mechanisms underlying nonhistaminergic itch, despite the fact that the majority of chronic itch are mediated by nonhistaminergic mechanisms. During the past few years, important progress has been made in understanding the molecular signaling of itch, largely due to the introduction of mouse genetics. In this review, we examine some of the molecular mechanisms underlying itch sensation with an emphasis on recent studies in rodents.
Collapse
Affiliation(s)
- Joseph Jeffry
- Center for the Study of Itch, Department of Anesthesiology, Washington University School of Medicine Pain Center, St. Louis, Missouri, USA
| | | | | |
Collapse
|
103
|
|
104
|
Abstract
The physiological effects of many extracellular neurotransmitters, hormones, growth factors, and other stimuli are mediated by receptor-promoted activation of phospholipase C (PLC) and consequential activation of inositol lipid signaling pathways. These signaling responses include the classically described conversion of phosphatidylinositol(4,5)P(2) to the Ca(2+)-mobilizing second messenger inositol(1,4,5)P(3) and the protein kinase C-activating second messenger diacylglycerol as well as alterations in membrane association or activity of many proteins that harbor phosphoinositide binding domains. The 13 mammalian PLCs elaborate a minimal catalytic core typified by PLC-d to confer multiple modes of regulation of lipase activity. PLC-b isozymes are activated by Gaq- and Gbg-subunits of heterotrimeric G proteins, and activation of PLC-g isozymes occurs through phosphorylation promoted by receptor and non-receptor tyrosine kinases. PLC-e and certain members of the PLC-b and PLC-g subclasses of isozymes are activated by direct binding of small G proteins of the Ras, Rho, and Rac subfamilies of GTPases. Recent high resolution three dimensional structures together with biochemical studies have illustrated that the X/Y linker region of the catalytic core mediates autoinhibition of most if not all PLC isozymes. Activation occurs as a consequence of removal of this autoinhibition.
Collapse
|
105
|
Tappe-Theodor A, Constantin CE, Tegeder I, Lechner SG, Langeslag M, Lepcynzsky P, Wirotanseng RI, Kurejova M, Agarwal N, Nagy G, Todd A, Wettschureck N, Offermanns S, Kress M, Lewin GR, Kuner R. Gαq/11 signaling tonically modulates nociceptor function and contributes to activity-dependent sensitization. Pain 2012; 153:184-196. [DOI: 10.1016/j.pain.2011.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 10/07/2011] [Accepted: 10/07/2011] [Indexed: 12/15/2022]
|
106
|
Unidirectional cross-activation of GRPR by MOR1D uncouples itch and analgesia induced by opioids. Cell 2011; 147:447-58. [PMID: 22000021 DOI: 10.1016/j.cell.2011.08.043] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 07/20/2011] [Accepted: 08/08/2011] [Indexed: 12/21/2022]
Abstract
Spinal opioid-induced itch, a prevalent side effect of pain management, has been proposed to result from pain inhibition. We now report that the μ-opioid receptor (MOR) isoform MOR1D is essential for morphine-induced scratching (MIS), whereas the isoform MOR1 is required only for morphine-induced analgesia (MIA). MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, relaying itch information. We show that morphine triggers internalization of both GRPR and MOR1D, whereas GRP specifically triggers GRPR internalization and morphine-independent scratching. Providing potential insight into opioid-induced itch prevention, we demonstrate that molecular and pharmacologic inhibition of PLCβ3 and IP3R3, downstream effectors of GRPR, specifically block MIS but not MIA. In addition, blocking MOR1D-GRPR association attenuates MIS but not MIA. Together, these data suggest that opioid-induced itch is an active process concomitant with but independent of opioid analgesia, occurring via the unidirectional cross-activation of GRPR signaling by MOR1D heterodimerization.
Collapse
|
107
|
Han SK, Simon MI. Intracellular Signaling and the Origins of the Sensations of Itch and Pain. Sci Signal 2011; 4:pe38. [DOI: 10.1126/scisignal.2002353] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
108
|
Oude Elferink RPJ, Kremer AE, Martens JJWW, Beuers UH. The molecular mechanism of cholestatic pruritus. Dig Dis 2011; 29:66-71. [PMID: 21691108 DOI: 10.1159/000324131] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pruritus is a frequent symptom in patients with cholestatic liver diseases. Pruritus can be excruciating and, in rare cases, become a primary indication for liver transplantation. The molecular mechanism of itch signal transduction is largely unclear. It was our hypothesis that compounds which accumulate in the circulation during cholestasis act as direct or indirect pruritogens by affecting signaling in itch fibers. To test this, we screened plasma samples of a large group of patients with various cholestatic conditions for their capacity to activate neuroblastoma cells. Quite strikingly, we found that samples from itchy cholestatic patients caused a significantly higher activation than samples from non-itchy cholestatic patients and healthy controls. Purification revealed lysophosphatidic acid (LPA) as the active compound. LPA is a very potent signaling lipid that can activate cells through various LPA receptors. Subsequently, we could demonstrate that cholestatic patients with pruritus have highly elevated levels of serum autotaxin (ATX), the enzyme that converts lysophosphatidylcholine into LPA. This is a striking finding as ATX has never been connected to itch perception thus far. We have also shown that LPA, when injected intradermally, causes itching in mice. On the basis of our results, we hypothesize that during cholestasis, expression of ATX is induced and gives rise to increased local formation of LPA near unmyelinated nerve endings of itch fibers. LPA then activates these neurons through one of the LPA receptors, which in turn potentiates action potentials along itch fibers.
Collapse
Affiliation(s)
- Ronald P J Oude Elferink
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
109
|
Rossbach K, Nassenstein C, Gschwandtner M, Schnell D, Sander K, Seifert R, Stark H, Kietzmann M, Bäumer W. Histamine H1, H3 and H4 receptors are involved in pruritus. Neuroscience 2011; 190:89-102. [PMID: 21689731 DOI: 10.1016/j.neuroscience.2011.06.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 05/27/2011] [Accepted: 06/01/2011] [Indexed: 12/12/2022]
Abstract
Histamine has long been recognised as a classical inducer of pruritus. However, the specific mechanism of histamine-induced itch has still not been fully understood. The H1 and H4 receptor appear to be key components in the induction of itch. The specific role of the H3 receptor in histamine-induced itch remains unclear. The aim of our study was to investigate the role of the four known histamine receptors (H1-4) in acute itch in mice. Intradermal injection of the selective H3R inverse agonist pitolisant induced strong itch in mice. Pitolisant (50 nmol/injection)-induced pruritus could be completely blocked by a combined treatment with the H1R antagonist cetirizine (15 mg/kg) and the H4R antagonist JNJ 7777120 (15 mg/kg), whereas the H2R antagonist ranitidine (15 mg/kg) failed to inhibit the scratch response. Next, expression and function of histamine receptors on sensory neurons isolated from dorsal root ganglia of mice were investigated. As the itch sensation results from the excitation of sensory nerves in the skin, we further focused on skin specific sensory neurons. Therefore, neurons were retrograde labelled from the skin by means of a fluorescent tracer. Expression of H1R, H3R and H4R on skin innervating sensory neurons was detected. By single-cell calcium imaging, it was demonstrated that histamine induces a calcium increase in a subset of (skin-specific) sensory neurons via activation of the H1R and H4R as well as inhibition of the H3R. It is assumed that the decreased threshold in response to H3R antagonism activates H1R and H4R on sensory neurons, which in turn results in the excitation of histamine-sensitive afferents and therefore elicits the sensation of itch.
Collapse
Affiliation(s)
- K Rossbach
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559 Hannover, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
110
|
Abstract
Chronic itch represents a burdensome clinical problem that can originate from a variety of aetiologies. Pruriceptive itch originates following the activation of peripheral sensory nerve endings following damage or exposure to inflammatory mediators and ascends to the brain through the spinal thalamic tract. Much insight has been gained into the understanding of the mechanisms underlying pruriceptive itch through studies using humans and experimental animals. More than one sensory nerve subtype is thought to subserve pruriceptive itch which includes both unmyelinated C-fibres and thinly myelinated Aδ nerve fibres. There are a myriad of mediators capable of stimulating these afferent nerves leading to itch, including biogenic amines, proteases, cytokines, and peptides. Some of these mediators can also evoke sensations of pain and the sensory processing underlying both sensations overlaps in complex ways. Studies have demonstrated that both peripheral and central sensitization to pruritogenic stimuli occur during chronic itch.
Collapse
Affiliation(s)
- C Potenzieri
- Division of Allergy and Clinical Immunology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | |
Collapse
|
111
|
Patel KN, Liu Q, Meeker S, Undem BJ, Dong X. Pirt, a TRPV1 modulator, is required for histamine-dependent and -independent itch. PLoS One 2011; 6:e20559. [PMID: 21655234 PMCID: PMC3105090 DOI: 10.1371/journal.pone.0020559] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 05/03/2011] [Indexed: 12/14/2022] Open
Abstract
Itch, or pruritus, is an important clinical problem whose molecular basis has yet to be understood. Recent work has begun to identify genes that contribute to detecting itch at the molecular level. Here we show that Pirt, known to play a vital part in sensing pain through modulation of the transient receptor potential vanilloid 1 (TRPV1) channel, is also necessary for proper itch sensation. Pirt−/− mice exhibit deficits in cellular and behavioral responses to various itch-inducing compounds, or pruritogens. Pirt contributes to both histaminergic and nonhistaminergic itch and, crucially, is involved in forms of itch that are both TRPV1-dependent and -independent. Our findings demonstrate that the function of Pirt extends beyond nociception via TRPV1 regulation to its role as a critical component in several itch signaling pathways.
Collapse
Affiliation(s)
- Kush N. Patel
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Qin Liu
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Sonya Meeker
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Bradley J. Undem
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail:
| |
Collapse
|
112
|
Abstract
PURPOSE OF REVIEW Pruritus is a frequent symptom in patients with cholestatic liver diseases. Itching may be excruciating, may seriously impair quality of life and even induce suicidal ideation in the most severe cases. RECENT FINDINGS The molecular mechanism of itch signal transduction in cholestasis is largely unclear. It may be caused or potentiated by compounds that accumulate in the circulation during cholestasis, which either directly or indirectly affect signalling in itch fibres. In the past, bile salts and endogenous opioids have been proposed but never been proven to be key factors in itch perception during cholestasis. We have performed a screen for compounds in plasma from patients with various cholestatic conditions for their capacity to activate neuronal cell lines. In these sera, we could identify a potent neuronal activator as lysophosphatidic acid (LPA). LPA is a very potent signalling phospholipid that can activate cells through various LPA receptors. Quite strikingly, samples from itchy cholestatic patients contained higher amounts of LPA. These increased levels of LPA turned out to be caused by elevated levels of serum autotaxin, the enzyme that converts lysophosphatidylcholine into LPA. This is a striking finding, as autotaxin has never been connected to itch perception thus far. We have also shown that LPA, when injected intradermally, caused scratching behaviour in mice. SUMMARY On the basis of our results, we hypothesize that during cholestasis expression of autotaxin is induced, which gives rise to increased local formation of LPA near unmyelinated nerve endings of itch fibres. LPA activates these neurons through one of the LPA receptors, which in turn potentiates action potentials along itch fibres leading to the perception of pruritus.
Collapse
|
113
|
TRPA1 is required for histamine-independent, Mas-related G protein-coupled receptor-mediated itch. Nat Neurosci 2011; 14:595-602. [PMID: 21460831 PMCID: PMC3181150 DOI: 10.1038/nn.2789] [Citation(s) in RCA: 447] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 02/28/2011] [Indexed: 12/28/2022]
Abstract
Itch, the unpleasant sensation that evokes a desire to scratch, accompanies numerous skin and nervous system disorders. In many cases, pathological itch is insensitive to antihistamine treatment. Recent studies have identified members of the Mas-related G protein-coupled receptor (Mrgpr) family that are activated by mast cell mediators and promote histamine-independent itch. MrgprA3 and MrgprC11 act as receptors for the pruritogens chloroquine and BAM8-22, respectively. However, the signaling pathways and transduction channels activated downstream of these pruritogens are largely unknown. We found that TRPA1 is the downstream target of both MrgprA3 and MrgprC11 in cultured sensory neurons and heterologous cells. TRPA1 is required for Mrgpr-mediated signaling, as sensory neurons from TRPA1-deficient mice exhibited markedly diminished responses to chloroquine and BAM8-22. Similarly, TRPA1-deficient mice displayed little to no scratching in response to these pruritogens. Our findings indicate that TRPA1 is an essential component of the signaling pathways that promote histamine-independent itch.
Collapse
|
114
|
Analysis of cellular and behavioral responses to imiquimod reveals a unique itch pathway in transient receptor potential vanilloid 1 (TRPV1)-expressing neurons. Proc Natl Acad Sci U S A 2011; 108:3371-6. [PMID: 21300878 DOI: 10.1073/pnas.1019755108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Despite its clinical importance, the mechanisms that mediate or generate itch are poorly defined. The identification of pruritic compounds offers insight into understanding the molecular and cellular basis of itch. Imiquimod (IQ) is an agonist of Toll-like receptor 7 (TLR7) used to treat various infectious skin diseases such as genital warts, keratosis, and basal cell carcinoma. Itch is reportedly one of the major side effects developed during IQ treatments. We found that IQ acts as a potent itch-evoking compound (pruritogen) in mice via direct excitation of sensory neurons. Combined studies of scratching behavior, patch-clamp recording, and Ca(2+) response revealed the existence of a unique intracellular mechanism, which is independent of TLR7 as well as different from the mechanisms exploited by other well-characterized pruritogens. Nevertheless, as for other pruritogens, IQ requires the presence of transient receptor potential vanilloid 1 (TRPV1)-expressing neurons for itch-associated responses. Our data provide evidence supporting the hypothesis that there is a specific subset of TRPV1-expressing neurons that is equipped with diverse intracellular mechanisms that respond to histamine, chloroquine, and IQ.
Collapse
|
115
|
Abstract
The itch field has made great advances in recent years, building upon earlier work to form a clearer picture of the biology behind this important sensory modality. Models for how itch is encoded have emerged that fit with physiological, molecular, and behavioral data. The molecular mechanisms of itch, both peripherally and centrally, are being revealed with the aid of newer animal models. Future work must address shortcomings in our current understanding of itch including limitations of current experimental methods. Here we review what is known about the cells, molecules, and circuits involved in itch and highlight key questions that remain to be answered.
Collapse
Affiliation(s)
- Kush N. Patel
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, United States
| |
Collapse
|
116
|
Abstract
The description of itch (formally known as pruritus) as an "unpleasant sensation that elicits the desire or reflex to scratch" (Ikoma et al., 2006) is immediately familiar. Research in the field of pruritoception has added to our understanding of this area of sensory neurobiology as it pertains to both normal and pathological conditions. In particular, much progress has been made on the mechanisms and circuits of itch, which we review here.
Collapse
Affiliation(s)
- Kush N Patel
- The Solomon H Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | |
Collapse
|
117
|
VGLUT2-dependent sensory neurons in the TRPV1 population regulate pain and itch. Neuron 2010; 68:529-42. [PMID: 21040852 DOI: 10.1016/j.neuron.2010.09.016] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2010] [Indexed: 12/19/2022]
Abstract
The natural response to itch sensation is to scratch, which relieves the itch through an unknown mechanism. Interaction between pain and itch has been frequently demonstrated, and the selectivity hypothesis of itch, based on data from electrophysiological and behavioral experiments, postulates the existence of primary pain afferents capable of repressing itch. Here, we demonstrate that deletion of vesicular glutamate transporter (VGLUT) 2 in a subpopulation of neurons partly overlapping with the vanilloid receptor (TRPV1) primary afferents resulted in a dramatic increase in itch behavior accompanied by a reduced responsiveness to thermal pain. The increased itch behavior was reduced by administration of antihistaminergic drugs and by genetic deletion of the gastrin-releasing peptide receptor, demonstrating a dependence on VGLUT2 to maintain normal levels of both histaminergic and nonhistaminergic itch. This study establishes that VGLUT2 is a major player in TRPV1 thermal nociception and also serves to regulate a normal itch response.
Collapse
|
118
|
Davidson S, Giesler GJ. The multiple pathways for itch and their interactions with pain. Trends Neurosci 2010; 33:550-8. [PMID: 21056479 DOI: 10.1016/j.tins.2010.09.002] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 09/03/2010] [Accepted: 09/10/2010] [Indexed: 12/12/2022]
Abstract
Multiple neural pathways and molecular mechanisms responsible for producing the sensation of itch have recently been identified, including histamine-independent pathways. Physiological, molecular, behavioral and brain imaging studies are converging on a description of these pathways and their close association with pain processing. Some conflicting results have arisen and the precise relationship between itch and pain remains controversial. A better understanding of the generation of itch and of the intrinsic mechanisms that inhibit itch after scratching should facilitate the search for new methods to alleviate clinical pruritus (itch). In this review we describe the current understanding of the production and inhibition of itch. A model of itch processing within the CNS is proposed.
Collapse
Affiliation(s)
- Steve Davidson
- Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | | |
Collapse
|
119
|
Akiyama T, Carstens MI, Carstens E. Facial injections of pruritogens and algogens excite partly overlapping populations of primary and second-order trigeminal neurons in mice. J Neurophysiol 2010; 104:2442-50. [PMID: 20739601 DOI: 10.1152/jn.00563.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intradermal cheek injection of pruitogens or algogens differentially elicits hindlimb scratching or forelimb wiping, suggesting that these behaviors distinguish between itch and pain. We studied whether pruritogens and algogens excite separate or overlapping populations of primary afferent and second-order trigeminal neurons in mice. Calcium imaging of primary sensory trigeminal ganglion (TG) cells showed that 15.4% responded to histamine, 5.8% to the protease-activated receptor (PAR)-2 agonist, 13.4% to allyl isothiocyanate (AITC), and 36.7% to capsaicin. AITC and/or capsaicin activated the vast majority of histamine- and PAR-2 agonist-sensitive TG cells. A chemical search strategy identified second-order neurons in trigeminal subnucleus caudalis (Vc) responsive to histamine, the PAR-2 agonist, or AITC. A minority of histamine or PAR-2 agonist-responsive Vc neurons responded to the other pruritogen, whereas a large majority of puritogen-responsive Vc neurons responded to capsaicin and/or AITC. A minority of AITC-responsive Vc neurons responded to pruritogens, whereas most responded to capsaicin. These data indicate that most primary and higher-order trigeminal sensory neurons are activated by both pruritic and algesic stimuli, although a minority exhibit selectivity. The results are discussed in terms of population codes for itch and pain that result in distinct behavioral responses of hindlimb scratching and forelimb wiping that are mediated at lumbar and cervical segmental levels, respectively.
Collapse
Affiliation(s)
- T Akiyama
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, USA
| | | | | |
Collapse
|
120
|
Akiyama T, Carstens IM, Carstens E. Enhanced scratching evoked by PAR-2 agonist and 5-HT but not histamine in a mouse model of chronic dry skin itch. Pain 2010; 151:378-383. [PMID: 20709455 DOI: 10.1016/j.pain.2010.07.024] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 06/17/2010] [Accepted: 07/20/2010] [Indexed: 12/26/2022]
Abstract
Chronic itch is a symptom of many skin conditions and systemic disease, and it has been hypothesized that the chronic itch may result from sensitization of itch-signaling pathways. We induced experimental chronic dry skin on the rostral back of mice, and observed a significant increase in spontaneous hindlimb scratches directed to the dry skin. Spontaneous scratching was significantly attenuated by a PAR-2 antibody and 5-HT2A receptor antagonist, indicating activation of these receptors by endogenous mediators released under dry skin conditions. We also observed a significant increase in the number of scratch bouts evoked by acute intradermal injections of a protease-activated receptor (PAR)-2 agonist and serotonin (5-HT), but not histamine. We additionally investigated if pruritogen-evoked activity of dorsal root ganglion (DRG) neurons is enhanced in this model. DRG cells from dry skin mice exhibited significantly larger responses to the PAR-2 agonist and 5-HT, but not histamine. Spontaneous scratching may reflect ongoing itch, and enhanced pruritogen-evoked scratching may represent hyperknesis (enhanced itch), both potentially due to sensitization of itch-signaling neurons. The correspondence between enhanced behavioral scratching and DRG cell responses suggest that peripheral pruriceptors that respond to proteases and 5-HT, but not histamine, may be sensitized in dry skin itch.
Collapse
Affiliation(s)
- T Akiyama
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA
| | | | | |
Collapse
|
121
|
Kim HJ, Kim KM, Noh MS, Yoo HJ, Lee CH. Glucosylsphingosine Induces Itch-Scratch Responses in Mice. Biomol Ther (Seoul) 2010. [DOI: 10.4062/biomolther.2010.18.3.316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
122
|
Abstract
Clinical pain conditions may remain responsive to opiate analgesics for extended periods, but such persistent acute pain can undergo a transition to an opiate-resistant chronic pain state that becomes a much more serious clinical problem. To test the hypothesis that cellular mechanisms of chronic pain in the primary afferent also contribute to the development of opiate resistance, we used a recently developed model of the transition of from acute to chronic pain, hyperalgesic priming. Repeated intradermal administration of the potent and highly selective mu-opioid agonist, [d-Ala(2),N-MePhe(4),gly-ol]-enkephalin (DAMGO), to produce tolerance for its inhibition of prostaglandin E(2) hyperalgesia, simultaneously produced hyperalgesic priming. Conversely, injection of an inflammogen, carrageenan, used to produce priming produced DAMGO tolerance. Both effects were prevented by inhibition of protein kinase Cepsilon (PKCepsilon). Carrageenan also induced opioid dependence, manifest as mu-opioid receptor antagonist (d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH(2))-induced hyperalgesia that, like priming, was PKCepsilon and G(i) dependent. These findings suggest that the transition from acute to chronic pain, and development of mu-opioid receptor tolerance and dependence may be linked by common cellular mechanisms in the primary afferent.
Collapse
|
123
|
Liu Q, Tang Z, Surdenikova L, Kim S, Patel KN, Kim A, Ru F, Guan Y, Weng HJ, Geng Y, Undem BJ, Kollarik M, Chen ZF, Anderson DJ, Dong X. Sensory neuron-specific GPCR Mrgprs are itch receptors mediating chloroquine-induced pruritus. Cell 2009; 139:1353-65. [PMID: 20004959 PMCID: PMC2989405 DOI: 10.1016/j.cell.2009.11.034] [Citation(s) in RCA: 590] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 09/14/2009] [Accepted: 11/04/2009] [Indexed: 12/13/2022]
Abstract
The cellular and molecular mechanisms mediating histamine-independent itch in primary sensory neurons are largely unknown. Itch induced by chloroquine (CQ) is a common side effect of this widely used antimalarial drug. Here, we show that Mrgprs, a family of G protein-coupled receptors expressed exclusively in peripheral sensory neurons, function as itch receptors. Mice lacking a cluster of Mrgpr genes display significant deficits in itch induced by CQ but not histamine. CQ directly excites sensory neurons in an Mrgpr-dependent manner. CQ specifically activates mouse MrgprA3 and human MrgprX1. Loss- and gain-of-function studies demonstrate that MrgprA3 is required for CQ responsiveness in mice. Furthermore, MrgprA3-expressing neurons respond to histamine and coexpress gastrin-releasing peptide, a peptide involved in itch sensation, and MrgprC11. Activation of these neurons with the MrgprC11-specific agonist BAM8-22 induces itch in wild-type but not mutant mice. Therefore, Mrgprs may provide molecular access to itch-selective neurons and constitute novel targets for itch therapeutics.
Collapse
Affiliation(s)
- Qin Liu
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Zongxiang Tang
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Lenka Surdenikova
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
- Department of Pathophysiology, Jessenius Medical School, Martin, Slovakia
| | - Seungil Kim
- Departments of Anesthesiology, Psychiatry, and Developmental Biology, Washington University School of Medicine Pain Center, St. Louis, MO 63110
| | - Kush N. Patel
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Andrew Kim
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Fei Ru
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Yun Guan
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Hao-Jui Weng
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Yixun Geng
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Bradley J. Undem
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Marian Kollarik
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Zhou-Feng Chen
- Departments of Anesthesiology, Psychiatry, and Developmental Biology, Washington University School of Medicine Pain Center, St. Louis, MO 63110
| | - David J. Anderson
- Division of Biology, California Institute of Technology, Pasadena, CA 91125
- Howard Hughes Medical Institute
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
- Howard Hughes Medical Institute
| |
Collapse
|
124
|
Histamine potentiates acid-induced responses mediating transient receptor potential V1 in mouse primary sensory neurons. Neuroscience 2009; 166:292-304. [PMID: 20006972 DOI: 10.1016/j.neuroscience.2009.12.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 11/27/2009] [Accepted: 12/01/2009] [Indexed: 01/06/2023]
Abstract
In inflamed tissues, extracellular pH decreases and acidosis is an important source of pain. Histamine is released from mast cells under inflammatory conditions and evokes the pain sensation in vivo, but the cellular mechanism of histamine-induced pain has not been well understood. In the present study, we examined the effects of histamine on [Ca(2+)](i) and membrane potential responses to acid in isolated mouse dorsal root ganglion (DRG) neurons. In capsaicin-sensitive DRG neurons from wild-type mice, acid (>pH 5.0) evoked [Ca(2+)](i) increases, but not in DRG neurons from transient receptor potential V1 (TRPV1) (-/-) mice. Regardless of isolectin GS-IB4 (IB4)-staining, histamine potentiated [Ca(2+)](i) responses to acid (>or=pH 6.0) that were mediated by TRPV1 activation. Histamine increased membrane depolarization induced by acid and evoked spike discharges. RT-PCR indicated the expression of all four histamine receptors (H1R, H2R, H3R, H4R) in mouse DRG. The potentiating effect of histamine was mimicked by an H1R agonist, but not H2R-H4R agonists and was inhibited only by an H1R antagonist. Histamine failed to potentiate the [Ca(2+)](i) response to acid in the presence of inhibitors for phospholipase C (PLC) and protein kinase C (PKC). A lipoxygenase inhibitor and protein kinase A inhibitor did not affect the potentiating effects of histamine. Carrageenan and complete Freund's adjuvant produced inflammatory hyperalgesia, but these inflammatory conditions did not change the potentiating effects of histamine in DRG neurons. The present results suggest that histamine sensitizes acid-induced responses through TRPV1 activation via H1R coupled with PLC/PKC pathways, the action of which may be involved in the generation of inflammatory pain.
Collapse
|
125
|
Mishra SK, Hoon MA. Ablation of TrpV1 neurons reveals their selective role in thermal pain sensation. Mol Cell Neurosci 2009; 43:157-63. [PMID: 19853036 DOI: 10.1016/j.mcn.2009.10.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 10/12/2009] [Indexed: 11/28/2022] Open
Abstract
Here we make use of neural ablation to investigate the properties of the TrpV1-expressing neurons in the trigeminal and dorsal root ganglia of mice. Resiniferotoxin (RTX), a potent TrpV1 agonist, administered either by direct injection in the ganglion or intrathecally killed approximately 70% of TrpV1 cells and resulted in modest thermal analgesia. Interestingly, after carageenan injection in the hind paw, the analgesic effects of RTX were dramatically increased with mice now paradoxically showing far less response to heat applied at sites of inflammation. This additional carageenan and RTX-induced analgesia was transient, lasting less than 2 days, and likely resulted from deafferentation of remaining TrpV1 neurons. Remarkably, although RTX affected sensitivity to heat, mechanical sensitivity (both of normal and inflamed tissue) was completely unaltered by toxin-mediated silencing of the TrpV1 sensory input. Thus, our data demonstrate that TrpV1 neurons are selectively tuned nociceptors that mediate responses to thermal but not mechanical pain and insinuate a labeled line model for somatosensory coding.
Collapse
Affiliation(s)
- Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, NIDCR, NIH Building 49, Room 1A16, 49 Convent Drive, Bethesda, MD 20892, USA
| | | |
Collapse
|
126
|
Litosch I, Pujari R, Lee SJ. Phosphatidic acid regulates signal output by G protein coupled receptors through direct interaction with phospholipase C-β1. Cell Signal 2009; 21:1379-84. [DOI: 10.1016/j.cellsig.2009.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 04/27/2009] [Indexed: 12/25/2022]
|
127
|
TRPV1-expressing primary afferents generate behavioral responses to pruritogens via multiple mechanisms. Proc Natl Acad Sci U S A 2009; 106:11330-5. [PMID: 19564617 DOI: 10.1073/pnas.0905605106] [Citation(s) in RCA: 323] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The mechanisms that generate itch are poorly understood at both the molecular and cellular levels despite its clinical importance. To explore the peripheral neuronal mechanisms underlying itch, we assessed the behavioral responses (scratching) produced by s.c. injection of various pruritogens in PLCbeta3- or TRPV1-deficient mice. We provide evidence that at least 3 different molecular pathways contribute to the transduction of itch responses to different pruritogens: 1) histamine requires the function of both PLCbeta3 and the TRPV1 channel; 2) serotonin, or a selective agonist, alpha-methyl-serotonin (alpha-Me-5-HT), requires the presence of PLCbeta3 but not TRPV1, and 3) endothelin-1 (ET-1) does not require either PLCbeta3 or TRPV1. To determine whether the activity of these molecules is represented in a particular subpopulation of sensory neurons, we examined the behavioral consequences of selectively eliminating 2 nonoverlapping subsets of nociceptors. The genetic ablation of MrgprD(+) neurons that represent approximately 90% of cutaneous nonpeptidergic neurons did not affect the scratching responses to a number of pruritogens. In contrast, chemical ablation of the central branch of TRPV1(+) nociceptors led to a significant behavioral deficit for pruritogens, including alpha-Me-5-HT and ET-1, that is, the TRPV1-expressing nociceptor was required, whether or not TRPV1 itself was essential. Thus, TRPV1 neurons are equipped with multiple signaling mechanisms that respond to different pruritogens. Some of these require TRPV1 function; others use alternate signal transduction pathways.
Collapse
|
128
|
Novel functional aspect of antihistamines: the impact of bepotastine besilate on substance p-induced events. J Allergy (Cairo) 2009; 2009:853687. [PMID: 20975801 PMCID: PMC2958303 DOI: 10.1155/2009/853687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Revised: 03/18/2009] [Accepted: 04/11/2009] [Indexed: 11/17/2022] Open
Abstract
Besides histamine, substance P (SP) has been demonstrated to play a crucial role in pruritic skin diseases. Although antihistamines are frequently used for pruritic skin diseases, little is known concerning the effect on an SP-induced event such as mast cell degranulation and the upregulation of adhesion molecules or the nitric oxide (NO) synthesis in endothelial cells. Our aim was to study the effect of bepotastine besilate on SP-induced degranulation of rat basophillic leukemia (RBL-2H3) cells and expression of adhesion molecules and NO synthesis in human dermal microvascular endothelial cells (HMVECs). Bepotastine besilate significantly inhibited SP-induced degranulation of RBL-2H3 cells and NO synthesis in HMVECs. Bepotastine besilate significantly inhibited expression of adhesion molecules in HMVESs, while it failed to suppress SP-induced upregulation of the adhesion molecules in HMVECs. Therefore, bepotastine besilate is assumed to act favorably on SP-induced basophil degranulation and NO synthesis in HMVECs.
Collapse
|
129
|
Gazerani P, Pedersen NS, Drewes AM, Arendt-Nielsen L. Botulinum toxin type A reduces histamine-induced itch and vasomotor responses in human skin. Br J Dermatol 2009; 161:737-45. [PMID: 19624547 DOI: 10.1111/j.1365-2133.2009.09305.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Clinical evidence has revealed the antipruritic effect of botulinum toxin type A (BoNT/A). BoNT/A is believed to be effective against itch as it inhibits the release of acetylcholine as well as some other substances that may be involved in itch. OBJECTIVES To investigate the effect of subcutaneous administration of BoNT/A on experimentally histamine-induced itch in human skin. METHODS In this double-blind, placebo-controlled study, 14 healthy men (mean +/- SD age 26.3 +/- 2.6 years) received BoNT/A (Botox; Allergan, Irvine, CA, U.S.A.; 5 U) and isotonic saline on the volar surface of either forearm. Histamine prick tests were performed four times at the treatment sites (before treatment, and days 1, 3 and 7 after treatment). The itch intensity (as rated on a 0-10 visual analogue scale), itch area, neurogenic inflammation (visible flare area), blood flow (laser Doppler) and cutaneous temperature (thermographic images) were measured over the course of the trials. RESULTS BoNT/A reduced the histamine-induced itch intensity (F(1,39) = 30.2, P < 0.001) and itch area (F(1,39) = 8.8, P = 0.011) compared with saline at all time points after treatment. The duration of itch was also shorter for BoNT/A-treated areas (F(1,39) = 19.4, P < 0.001), with a peak effect at day 7. The flare area was smaller in the BoNT/A-treated arm compared with the saline-treated arm at all time points after treatment (F(1,39) = 15.4, P = 0.002). Findings from blood flow (F(1,26) = 177.3, P < 0.001) and temperature measurements (F(1,26) = 27.6, P < 0.001) clearly showed the suppressive effect of BoNT/A on vasomotor reactions, with the maximal effect on days 3 and 7. CONCLUSIONS BoNT/A reduced the itch intensity, blood flow and neurogenic inflammation in response to the histamine prick test in human skin. The findings could be applicable in the treatment of some pruritic conditions that can be difficult to treat with conventional treatments.
Collapse
Affiliation(s)
- P Gazerani
- Center for Sensory-Motor Interaction, Department of Health Sciences and Technology, Aalborg University, DK-9220 Aalborg, Denmark
| | | | | | | |
Collapse
|
130
|
Phospholipase C{beta}3 in mouse and human dorsal root ganglia and spinal cord is a possible target for treatment of neuropathic pain. Proc Natl Acad Sci U S A 2008; 105:20004-8. [PMID: 19066214 DOI: 10.1073/pnas.0810899105] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Treatment of neuropathic pain is a major clinical problem. This study shows expression of phospholipase ss3 (PLCss3) in mouse and human DRG neurons, mainly in small ones and mostly with a nonpeptidergic phenotype. After spared nerve injury, the pain threshold was strongly reduced, and systemic treatment of such animals with the unselective PLC inhibitor U73122 caused a rapid and long-lasting (48-h) increase in pain threshold. Thus, inhibition of PLC may provide a way to treat neuropathic pain.
Collapse
|
131
|
Shim WS, Oh U. Histamine-induced itch and its relationship with pain. Mol Pain 2008; 4:29. [PMID: 18667087 PMCID: PMC2519061 DOI: 10.1186/1744-8069-4-29] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 07/31/2008] [Indexed: 05/25/2023] Open
Abstract
Itch is one of the major complications of skin diseases. Although there are various substances that induce itch or pruritus, it is evident that histamine is the best known endogenous agent that evokes itch. Even though histamine-induced itch has been studied for some time, the underlying mechanism of itch is just beginning to emerge. Although various downstream signaling pathways of histamine receptors have been revealed, more studies are required to determine the cause of histamine-induced itch. It appears that itch and pain involve different neuronal pathways. Pain generally inhibits itch, which indicates an inter-communication between the two. Complex interactions between itch and pain may be expected based on reports on disease states and opioids. In this review, we discuss the molecular mechanism and the pharmacological aspects of histamine-induced itch. Especially, the underlying mechanism of TRPV1 (an anti-pruritus target) has been determined to some extent.
Collapse
Affiliation(s)
- Won-Sik Shim
- National Research Laboratory of Transporters Targeted Drug Design, Research Institute of Pharmaceutical Sciences, College of Pharmacy,Seoul National University, Seoul, 151-742, Korea.
| | | |
Collapse
|
132
|
Abstract
We examined whether different itch signals converge on the same dorsal horn neurons in mice. Intradermal injections of histamine and SLIGRL-NH2 (protease-activated receptor-2 agonist) induced scratching in naive mice and so did mosquito allergen in sensitized mice. These stimuli induced Fos expression in cells in the superficial dorsal horn. Fos-positive cells were mainly distributed within the isolectin B4-labeled region (inner aspect of lamina II) after histamine injection. In contrast, they were in the region dorsal to the isolectin B4-labeled region after injections of SLIGRL-NH2 and mosquito allergen. These results suggest that allergic itch signal is mediated by primary afferents expressing protease-activated receptor-2 and the neurons receiving signals of protease-associated itch and allergy-associated itch are different from those of histamine-induced itch.
Collapse
|
133
|
Thurmond RL, Gelfand EW, Dunford PJ. The role of histamine H1 and H4 receptors in allergic inflammation: the search for new antihistamines. Nat Rev Drug Discov 2008; 7:41-53. [PMID: 18172439 DOI: 10.1038/nrd2465] [Citation(s) in RCA: 385] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Histamine has a key role in allergic inflammatory conditions. The inflammatory responses resulting from the liberation of histamine have long been thought to be mediated by the histamine H1 receptor, and H1-receptor antagonists--commonly known as antihistamines--have been used to treat allergies for many years. However, the importance of histamine in the pathology of conditions such as asthma and chronic pruritus may have been underestimated. Here, we review accumulating evidence suggesting that histamine indeed has roles in inflammation and immune function modulation in such diseases. In particular, the discovery of a fourth histamine receptor (H4) and its expression on numerous immune and inflammatory cells has prompted a re-evaluation of the actions of histamine, suggesting a new potential for H4-receptor antagonists and a possible synergy between H1 and H4-receptor antagonists in targeting various inflammatory conditions.
Collapse
Affiliation(s)
- Robin L Thurmond
- Johnson & Johnson Pharmaceutical Research & Development, L.L.C. San Diego, California 92121, USA.
| | | | | |
Collapse
|
134
|
Yu S, Kollarik M, Ouyang A, Myers AC, Undem BJ. Mast cell-mediated long-lasting increases in excitability of vagal C fibers in guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 2007; 293:G850-6. [PMID: 17702952 DOI: 10.1152/ajpgi.00277.2007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Several esophageal pathologies are associated with an increased number of mast cells in the esophageal wall. We addressed the hypothesis that activation of esophageal mast cells leads to an increase in the excitability of local sensory C fibers. Guinea pigs were actively sensitized to ovalbumin. The mast cells in the esophagus were selectively activated ex vivo by superfusion with ovalbumin. Action potential discharge in guinea pig vagal nodose esophageal C-fiber nerve endings was monitored in the isolated (ex vivo) vagally innervated esophagus by extracellular recordings. Ovalbumin activated esophageal mast cells, leading to the rapid release of approximately 20% of the tissue histamine stores. This was associated with a consistent and significant increase in excitability of the nodose C fibers as reflected in a two- to threefold increase in action potential discharge frequency evoked by mechanical (increases in intraluminal pressure) stimulation. The increase in excitability persisted unchanged for at least 90 min (longest time period tested) after ovalbumin was washed from the tissue. This effect could be prevented by the histamine H1 receptor antagonist pyrilamine, but once the increase in excitability occurred, it persisted in the nominal absence of histamine and could not be reversed even with large concentrations of the histamine receptor antagonist. In conclusion, activation of esophageal mast cells leads to a pronounced and long-lived increase in nociceptive C-fiber excitability such that any sensation or reflex evoked via the vagal nociceptors will likely be enhanced. The effect is initiated by histamine acting via H1 receptor activation and maintained in the absence of the initiating stimulus.
Collapse
Affiliation(s)
- Shaoyong Yu
- Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, USA
| | | | | | | | | |
Collapse
|
135
|
Nicolson TA, Foster AF, Bevan S, Richards CD. Prostaglandin E2 sensitizes primary sensory neurons to histamine. Neuroscience 2007; 150:22-30. [PMID: 17945428 DOI: 10.1016/j.neuroscience.2007.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 09/07/2007] [Accepted: 09/11/2007] [Indexed: 11/17/2022]
Abstract
1. Histamine is able to elicit a dose-dependent rise in intracellular Ca2+ in a proportion of rat dorsal root ganglion (DRG) neurons. Pre-treatment with prostaglandin (PGE2) prior to a histamine challenge increases the proportion of neurons responding to low concentrations of histamine (10-100 microM). 2. The dose-response curve for histamine is shifted to the left by approximately two orders of magnitude following 45 s pre-treatment with 1 microM PGE2. 3. The phospholipase C (PLC) inhibitor 1-[6-[[17-beta-3-methoxyestra-1,3,5(10)-trien-17-yl-]amino]hexyl]-1H-pyrrole-2,5-dione (U73122) completely blocked the response to histamine (100 microM) in non-sensitized cells but, after PGE2 pre-treatment, this inhibitor reduced the proportion of cells responding to histamine by approximately a half. Removal of extracellular Ca2+ blocked the response in the remaining cells so that, in this subgroup of histamine sensitive neurons, the PGE2 sensitization is the result of activation of a Ca influx pathway. 4. The sensitization is dependent on an increase in cAMP as it is mimicked by pre-treatment with 8-bromo cyclic AMP (8-Br-cAMP) and by forskolin stimulation of adenylyl cyclase activity. It is inhibited by THFA (tetrahydrofuryl adenine) an inhibitor of adenylyl cyclase. The sensitization is also blocked by pre-treatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), an inhibitor of protein kinase A. We conclude that the PGE2 sensitization of DRG neurons to histamine is dependent on activation of the cAMP-protein kinase A cascade.
Collapse
Affiliation(s)
- T A Nicolson
- Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK
| | | | | | | |
Collapse
|
136
|
Abstract
Although the role of prostanoids in itch was actively studied a decade ago, interest in this area has waned in recent years. Andoh et al. (2007, this issue) demonstrate that the prostanoid thromboxane A2 elicits scratching through its TP receptor. Identification of new itch mediators and their respective receptors within the skin will undoubtedly be the focus of future drug development for this distressing symptom.
Collapse
Affiliation(s)
- Gil Yosipovitch
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
| |
Collapse
|
137
|
Nomura S, Fukaya M, Tsujioka T, Wu D, Watanabe M. Phospholipase Cβ3 is distributed in both somatodendritic and axonal compartments and localized around perisynapse and smooth endoplasmic reticulum in mouse Purkinje cell subsets. Eur J Neurosci 2007; 25:659-72. [PMID: 17298601 DOI: 10.1111/j.1460-9568.2007.05334.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Phospholipase Cbeta3 (PLCbeta3) and PLCbeta4 are the two major isoforms in cerebellar Purkinje cells (PCs), displaying reciprocal expression across the cerebellum. Here, we examined subcellular distribution of PLCbeta3 in the mouse cerebellum by producing specific antibody. PLCbeta3 was detected as a particulate pattern of immunostaining in various PC elements. Like PLCbeta4, PLCbeta3 was richly distributed in somatodendritic compartments, where it was colocalized with molecules constituting the metabotropic glutamate receptor (mGluR1) signalling pathway, i.e. mGluR1alpha, G alpha q/G alpha 11 subunits of G q protein, inositol 1,4,5-trisphosphate receptor IP3R1, Homer1, protein kinase C PKCgamma, and diacylglycerol lipase DAGLalpha. Unlike PLCbeta4, PLCbeta3 was also distributed at low to moderate levels in PC axons, which were intense for IP3R1 and PKCgamma, low for G alpha q/G alpha 11, and negative for mGluR1alpha, Homer1, and DAGLalpha. By immunoelectron microscopy, PLCbeta3 was preferentially localized around the smooth endoplasmic reticulum in spines, dendrites, and axons of PCs, and also accumulated at the perisynapse of parallel fibre-PC synapses. Consistent with the ultrastructural localization, PLCbeta3 was biochemically enriched in the microsomal and postsynaptic density fractions. These results suggest that PLCbeta3 plays a major role in mediating mGluR1-dependent synaptic transmission, plasticity, and integration in PLCbeta3-dominant PCs, through eliciting Ca2+ release, protein phosphorylation, and endocannabinoid production at local somatodendritic compartments. Because PLCbeta3 can be activated by G betagamma subunits liberated from Gi/o and Gs proteins as well, axonal PLCbeta3 seems to modulate the conduction of action potentials through mediating local Ca2+ release and protein phosphorylation upon activation of a variety of G protein-coupled receptors other than mGluR1.
Collapse
Affiliation(s)
- Sachi Nomura
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | | | | | | | | |
Collapse
|
138
|
In Brief. Nat Rev Neurosci 2007. [DOI: 10.1038/nrn2071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|