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Tey HL, Yosipovitch G. Targeted treatment of pruritus: a look into the future. THE BRITISH JOURNAL OF DERMATOLOGY 2011. [PMID: 21219293 DOI: 10.1111/j.1365-2133.2011.10217.x.] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in pruritus research have elucidated mediators and neuronal pathways involved in itch transmission, and this fast emerging knowledge may possibly be translated into new therapies in the near future. In the skin and peripheral nerves, potential mediator and receptor therapeutic targets include the H4 histamine receptor, protease-activated receptor 2, serine proteases, cathepsin S, peripheral mu- and kappa-opioid receptors, interleukin-31, transient receptor potential vanilloid 1 and 3, fatty acid amide hydrolase, nerve growth factor and its receptor, acetylcholine, and the Mas-related G protein-coupled receptors. In the spinal cord, gastrin-related peptide and its receptor, as well as substance P and its receptor neurokinin receptor-1 serve as potential therapeutic targets. In the brain, reduction of itch perception and modulation of emotions may possibly be achieved through drugs acting on the anterior cingulate cortex. Clinically, management of pruritus should be instituted early and should address the skin pathology, peripheral neuropathy, central sensitization, and the cognito-affective aspects of the disease.
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Affiliation(s)
- H L Tey
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1071, USA
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403
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Abstract
Recent advances in pruritus research have elucidated mediators and neuronal pathways involved in itch transmission, and this fast emerging knowledge may possibly be translated into new therapies in the near future. In the skin and peripheral nerves, potential mediator and receptor therapeutic targets include the H4 histamine receptor, protease-activated receptor 2, serine proteases, cathepsin S, peripheral mu- and kappa-opioid receptors, interleukin-31, transient receptor potential vanilloid 1 and 3, fatty acid amide hydrolase, nerve growth factor and its receptor, acetylcholine, and the Mas-related G protein-coupled receptors. In the spinal cord, gastrin-related peptide and its receptor, as well as substance P and its receptor neurokinin receptor-1 serve as potential therapeutic targets. In the brain, reduction of itch perception and modulation of emotions may possibly be achieved through drugs acting on the anterior cingulate cortex. Clinically, management of pruritus should be instituted early and should address the skin pathology, peripheral neuropathy, central sensitization, and the cognito-affective aspects of the disease.
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Affiliation(s)
- H L Tey
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1071, USA
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404
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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.
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405
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Akiyama T, Carstens MI, Carstens E. Enhanced responses of lumbar superficial dorsal horn neurons to intradermal PAR-2 agonist but not histamine in a mouse hindpaw dry skin itch model. J Neurophysiol 2011; 105:2811-7. [PMID: 21430273 DOI: 10.1152/jn.01124.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic itch is symptomatic of many skin conditions and systemic diseases. Little is known about pathophysiological alterations in itch-signaling neural pathways associated with chronic itch. We used a mouse model of hindpaw chronic dry skin itch to investigate properties of presumptive itch-signaling neurons. Neurons in the lumbar superficial dorsal horn ipsilateral to hindpaw dry skin treatment exhibited a high level of spontaneous activity that was inhibited by scratching the plantar surface. Most spontaneously active units exhibited further increases in firing rate following intradermal injection of an agonist of the protease-activated receptor PAR-2, or histamine. The large majority of pruritogen-responsive units also responded to capsaicin and allyl isothiocyanate. For neurons ipsilateral to dry skin treatment, responses elicited by the PAR-2 agonist, but not histamine or mechanical stimuli, were significantly larger compared with neurons ipsilateral to vehicle (water) treatment or neurons recorded in naïve (untreated) mice. The spontaneous activity may signal ongoing itch, while enhanced PAR-2 agonist-evoked responses may underlie hyperknesis (enhanced itch), both of which are symptomatic of many chronic itch conditions. The enhancement of neuronal responses evoked by the PAR-2 agonist, but not by histamine or mechanical stimuli, implies that the dry skin condition selectively sensitized PAR-2 agonist-sensitive primary afferent pruriceptors.
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Affiliation(s)
- Tasuku Akiyama
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616, USA
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406
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Su PY, Ko MC. The role of central gastrin-releasing peptide and neuromedin B receptors in the modulation of scratching behavior in rats. J Pharmacol Exp Ther 2011; 337:822-9. [PMID: 21421741 DOI: 10.1124/jpet.111.178970] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bombesin is a pruritogenic agent that causes intense itch-scratching activity in rodents. Bombesin has high affinity for the gastrin-releasing peptide (GRP) receptor (GRPr) and the neuromedin B (NMB) receptor (NMBr). The aim of this study was to investigate pharmacologically the ability of GRPr and NMBr to elicit scratching behavior in rats. The intracerebroventricular route was selected for drug delivery because the study focused on supraspinal sites of action. The magnitude and duration of scratching produced by the naturally occurring peptides GRP and NMB were characterized. Antagonists selective for GRPr [(d-Tpi6, Leu13Ψ(CH2-NH)-Leu14)Bombesin(6-14) (RC-3095)] and NMBr [(S)-α-methyl-α-[[[(4-nitrophenyl)amino]carbonyl]amino]-N-[[1-(2-pyridinyl)cyclohexyl]methyl]-1H-indole-3-propanamide (PD168368)] were used to define the role of GRPr and NMBr in the scratching response. After intracerebroventricular administration, GRP (0.03-0.3 nmol) and NMB (0.1-1 nmol) dose-dependently elicited marked scratching. There was a tolerance to scratching elicited by daily repeated administration of bombesin, GRP, or NMB. Presession administration of RC-3095 (0.1-1 nmol) and PD168368 (0.3-3 nmol) dose-dependently antagonized scratching elicited by GRP and NMB, respectively. More importantly, 1 nmol of RC-3095 failed to block NMB-elicited scratching, and 3 nmol of PD168368 failed to block GRP-elicited scratching. In addition, pretreatment with effective doses of RC-3095 or PD168368 alone or in combination did not block bombesin-elicited scratching. Through the use of the selective antagonists RC-3095 and PD168368, this study demonstrates that central GRPr and NMBr act independently to elicit scratching behavior and there is an additional, unidentified receptor mechanism underlying bombesin-elicited scratching.
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Affiliation(s)
- Pin-Yen Su
- Institute of Neuroscience, College of Science, National Cheng Chi University, Wenshan District, Taipei 11605, Taiwan
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407
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Gotoh Y, Omori Y, Andoh T, Kuraishi Y. Tonic inhibition of allergic itch signaling by the descending noradrenergic system in mice. J Pharmacol Sci 2011; 115:417-20. [PMID: 21372505 DOI: 10.1254/jphs.10305sc] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
We investigated whether the descending noradrenergic system regulates allergic itch. Mosquito allergy of the hind paw elicited biting, an itch-related response, in sensitized mice. The biting was inhibited by intrathecal clonidine and reversed by yohimbine, an α(2)-adrenoceptor antagonist. The biting was increased by intrathecal pretreatment with the catecholaminergic neurotoxin 6-hydroxydopamine and the α-adrenoceptor antagonist phentolamine but not the serotonergic neurotoxin 5,7-dihydroxytryptamine. We propose that α(2)-adrenoceptors are involved in the inhibition of allergic itch in the spinal cord and that the descending noradrenergic system exerts a tonic inhibition on the itch signaling. The serotonergic system may not be involved.
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Affiliation(s)
- Yoshikazu Gotoh
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan
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408
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Abstract
Chronic itch could be a presenting sign of malignancy. Pruritus of lymphoma is the common prototype of paraneoplastic itch and can precede other clinical signs by weeks and months. Paraneoplastic pruritus has also been associated with solid tumors and is an important clinical symptom in paraneoplastic skin diseases such as erythroderma, Grovers disease, malignant acanthosis nigricans, generalized granuloma annulare, Bazex syndrome, and dermatomyositis. In any case with high index of suspicion a thorough work-up is required. This review highlights the association between itch and malignancy and presents new findings related to pathophysiological mechanisms and the treatment of itch associated with malignancy. Combinative therapies reducing itch sensitization and transmission using selective serotonin and neuroepinephrine reuptake inhibitors, Kappa opioids, and neuroleptics are of prime importance in reducing this bothersome symptom.
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Affiliation(s)
- Gil Yosipovitch
- Department of Dermatology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA.
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409
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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.
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410
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411
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412
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Kremer AE, Oude Elferink RPJ, Beuers U. Pathophysiology and current management of pruritus in liver disease. Clin Res Hepatol Gastroenterol 2011; 35:89-97. [PMID: 21809485 DOI: 10.1016/j.clinre.2010.10.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pruritus is frequently reported by patients with cholestatic hepatobiliary diseases such as primary biliary cirrhosis, primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy and hereditary cholestatic syndromes, but may accompany almost any other liver disease. Increased concentrations of bile salts, histamine, progesterone metabolites or endogenous opioids have been controversially discussed as potential pruritogens in cholestasis in the past. Most recently, novel insights unravelled lysophosphatidic acid (LPA), a potent neuronal activator, as a potential pruritogen in pruritus of cholestasis. Nevertheless, the pathogenesis of pruritus in cholestasis is still not clearly defined and current antipruritic treatment strategies provide relief only in a part of the affected patients. Based on recent experimental and clinical findings, this review outlines the actual insight in pathogenesis of pruritus in cholestasis and summarizes evidence-based and experimental therapeutic interventions for cholestatic patients suffering from itch.
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Affiliation(s)
- Andreas E Kremer
- Tytgat Institute for liver and intestinal research, Department of gastroenterology and hepatology, Academic Medical Center, S1-164, University of Amsterdam, Meibergdreef 69-71, NL-1105 BK Amsterdam, The Netherlands.
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413
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Inan S, Dun NJ, Cowan A. Investigation of gastrin-releasing peptide as a mediator for 5'-guanidinonaltrindole-induced compulsive scratching in mice. Peptides 2011; 32:286-92. [PMID: 21126550 PMCID: PMC3995915 DOI: 10.1016/j.peptides.2010.11.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 11/11/2010] [Accepted: 11/12/2010] [Indexed: 11/16/2022]
Abstract
Gastrin-releasing peptide (GRP) has been implicated in the itch-scratch cycle. We investigated if this gut-brain-skin peptide plays a role in the compulsive, hindleg scratching of the neck of mice by 5'-guanidinonaltrindole (GNTI), the kappa opioid receptor antagonist, and in the antipruritic activity of nalfurafine, the kappa opioid agonist. Previously, we showed that GNTI (0.03-1mg/kg, s.c.) elicits dose-related scratching and that nalfurafine (0.001-0.02mg/kg, s.c.) inhibits this behavior in mice. Utilizing immunohistochemistry, GRP positive nerve fibers were detected in mouse skin and superficial layer of the dorsal horn of the spinal cord as well as GRP positive cells in the dorsal root ganglion. Pretreating mice with either a pseudopeptide GRP receptor antagonist, RC-3095 (10-30mg/kg, s.c. at -15min), or a peptide GRP receptor antagonist, [d-Phe(6)]bombesin(6-13) methyl ester (2-100nmol, i.t. at -10min), did not suppress GNTI-induced scratching. However, pretreating mice with either antagonist inhibited scratching precipitated by the GRP receptor agonist, GRP(18-27) (2nmol, i.t.). Pretreating mice with a muscarinic M(1) receptor agonist, McN-A-343 (1.5-15μg/5μl, i.t. at -10min) antagonized GNTI-induced scratching. Norbinaltorphimine (20mg/kg, i.p. at -18 to -20h), a kappa opioid antagonist, countered the antiscratch activity of nalfurafine. We conclude that (a) the GRP receptor system does not mediate GNTI-induced scratching and (b) the kappa opioid system is involved, at least in part, in the scratch suppressing activity of nalfurafine.
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Affiliation(s)
- Saadet Inan
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Nae J Dun
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Alan Cowan
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA 19140, USA
- Corresponding author: Alan Cowan, PhD, Department of Pharmacology, Temple University School of Medicine, 3420 N Broad Street, Philadelphia, PA 19140, Telephone: (215)-707-4110, Fax: (215)-707-7068,
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414
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Abstract
PURPOSE OF REVIEW This review will highlight recent advances in the understanding of mammalian bombesin receptor-related pathophysiological roles in disease states and new insights into bombesin receptor pharmacology. RECENT FINDINGS Studies regarding bombesin-like peptides and mammalian bombesin receptor functions have demonstrated significant biological impact on a broad array of physiological and pathophysiological conditions. Pharmacological experiments in vitro and in vivo as well as utilization of genetic rodent models of the gastrin-releasing peptide receptor (GRP-R/BB2) and neuromedin B receptor (NMB-R/BB1) further delineated roles in memory and fear behavior, inhibition of tumor cell growth, mediating signals for pruritus and male reproductive behavior. All three mammalian bombesin receptors were shown to possess some role in the regulation of energy balance. Novel synthesis of selective high affinity agonists and antagonists of the orphan bombesin receptor subtype-3 (BRS-3/BB3) has been accomplished and will facilitate further studies using animal model systems. SUMMARY Mammalian bombesin receptors participate in the regulation of energy homeostasis and may represent an attractive target for pharmacological treatment of obesity and certain eating disorders. Novel pharmacological insights of bombesin-like peptides and the interaction with their respective receptors have been elucidated to aid future treatment and imaging of epithelial cell-derived tumors.
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Affiliation(s)
- Ishita D Majumdar
- Section of Gastroenterology, Boston University School of Medicine, Boston, Massachusetts, USA
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415
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2011; 18:83-98. [PMID: 21178692 DOI: 10.1097/med.0b013e3283432fa7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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416
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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.
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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
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417
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Viana F. Chemosensory properties of the trigeminal system. ACS Chem Neurosci 2011; 2:38-50. [PMID: 22778855 PMCID: PMC3369707 DOI: 10.1021/cn100102c] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 12/14/2010] [Indexed: 11/28/2022] Open
Abstract
The capacity of cutaneous, including trigeminal endings, to detect chemicals is known as chemesthesis or cutaneous chemosensation. This sensory function involves the activation of nociceptor and thermoreceptor endings and has a protective or defensive function, as many of these substances are irritants or poisonous. However, humans have also developed a liking for the distinct sharpness or pungency of many foods, beverages, and spices following activation of the same sensory afferents. Our understanding of the cellular and molecular mechanisms of chemosensation in the trigeminal system has experienced enormous progress in the past decade, following the cloning and functional characterization of several ion channels activated by physical and chemical stimuli. This brief review attempts to summarize our current knowledge in this field, including a functional description of various sensory channels, especially TRP channels, involved in trigeminal chemosensitivy. Finally, some of these new findings are discussed in the context of the pathophysiology of trigeminal chemosensation, including pain, pruritus, migraine, cough, airway inflammation, and ophthalmic diseases.
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Affiliation(s)
- Félix Viana
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, San Juan de Alicante, Spain.
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418
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Ständer S, Raap U, Weisshaar E, Schmelz M, Mettang T, Handwerker H, Luger TA. Pathogenesis of pruritus. J Dtsch Dermatol Ges 2011; 9:456-63. [DOI: 10.1111/j.1610-0387.2011.07585.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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419
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[What's new in dermatological research?]. Ann Dermatol Venereol 2011; 137 Suppl 4:S137-44. [PMID: 21193117 DOI: 10.1016/s0151-9638(10)70040-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dermatology research has been very rich this year, once again. The physiopathological mechanisms of paradoxical reactions to anti-TNF are better understood and new therapeutic targets for psoriasis have been evidenced. Targeted therapy in oncodermatology have shown their potential usefulness clinically but fundamental data have also clarified their mechanisms of action as well as their limits. The key role played by the immune system in nonsegmental vitiligo has also been clearly demonstrated. Fibroblasts as well as visible light seem to play a key role that has been poorly understood to date within the complex mechanisms of cutaneous pigmentation. Specific receptors of pruritus have been reported and foster hope for the development of more effective antipruriginous treatments in the near future. Other studies report new potential targets for diseases such as fungoid mycosis, atopic dermatitis, or scleroderma. Finally, physiopathological explanations have contributed to a variety of domains such as greying hair, axillary odors, HIV and herpes virus interrelations, and the teratogenicity of thalidomide.
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420
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Clonidine inhibits itch-related response through stimulation of α2-adrenoceptors in the spinal cord in mice. Eur J Pharmacol 2011; 650:215-9. [DOI: 10.1016/j.ejphar.2010.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/16/2010] [Accepted: 10/03/2010] [Indexed: 11/22/2022]
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421
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Liu Y, Abdel Samad O, Zhang L, Duan B, Tong Q, Lopes C, Ji RR, Lowell BB, Ma Q. VGLUT2-dependent glutamate release from nociceptors is required to sense pain and suppress itch. Neuron 2010; 68:543-56. [PMID: 21040853 DOI: 10.1016/j.neuron.2010.09.008] [Citation(s) in RCA: 202] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2010] [Indexed: 12/12/2022]
Abstract
Itch can be suppressed by painful stimuli, but the underlying neural basis is unknown. We generated conditional null mice in which vesicular glutamate transporter type 2 (VGLUT2)-dependent synaptic glutamate release from mainly Nav1.8-expressing nociceptors was abolished. These mice showed deficits in pain behaviors, including mechanical pain, heat pain, capsaicin-evoked pain, inflammatory pain, and neuropathic pain. The pain deficits were accompanied by greatly enhanced itching, as suggested by (1) sensitization of both histamine-dependent and histamine-independent itch pathways and (2) development of spontaneous scratching and skin lesions. Strikingly, intradermal capsaicin injection promotes itch responses in these mutant mice, as opposed to pain responses in control littermates. Consequently, coinjection of capsaicin was no longer able to mask itch evoked by pruritogenic compounds. Our studies suggest that synaptic glutamate release from a group of peripheral nociceptors is required to sense pain and suppress itch. Elimination of VGLUT2 in these nociceptors creates a mouse model of chronic neurogenic itch.
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Affiliation(s)
- Yang Liu
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115, USA
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422
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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.
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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
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423
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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.
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424
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The gastrin-releasing peptide system in the spinal cord mediates masculine sexual function. Anat Sci Int 2010; 86:19-29. [DOI: 10.1007/s12565-010-0097-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Accepted: 09/29/2010] [Indexed: 10/18/2022]
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425
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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.
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Affiliation(s)
- Steve Davidson
- Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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426
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Ma Q. Labeled lines meet and talk: population coding of somatic sensations. J Clin Invest 2010; 120:3773-8. [PMID: 21041959 DOI: 10.1172/jci43426] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The somatic sensory system responds to stimuli of distinct modalities, including touch, pain, itch, and temperature sensitivity. In the past century, great progress has been made in understanding the coding of these sensory modalities. From this work, two major features have emerged. First, there are specific neuronal circuits or labeled lines transmitting specific sensory information from the skin to the brain. Second, the generation of specific sensations often involves crosstalk among distinct labeled lines. These features suggest that population coding is the mechanism underlying somatic sensation.
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Affiliation(s)
- Qiufu Ma
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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427
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Toll-like receptor 7 mediates pruritus. Nat Neurosci 2010; 13:1460-2. [PMID: 21037581 DOI: 10.1038/nn.2683] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 10/04/2010] [Indexed: 01/08/2023]
Abstract
Toll-like receptors are typically expressed in immune cells to regulate innate immunity. We found that functional Toll-like receptor 7 (TLR7) was expressed in C-fiber primary sensory neurons and was important for inducing itch (pruritus), but was not necessary for eliciting mechanical, thermal, inflammatory and neuropathic pain in mice. Our results indicate that TLR7 mediates itching and is a potential therapeutic target for anti-itch treatment in skin disease conditions.
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428
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Liu Y, Ma Q. Generation of somatic sensory neuron diversity and implications on sensory coding. Curr Opin Neurobiol 2010; 21:52-60. [PMID: 20888752 DOI: 10.1016/j.conb.2010.09.003] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 08/27/2010] [Accepted: 09/03/2010] [Indexed: 11/30/2022]
Abstract
Neurons in the dorsal root ganglia (DRG) are composed of a variety of sensory modalities, three of which are pain-sensing nociceptors, temperature-sensing thermoceptors, and itch-sensing pruriceptors. All these neurons are emerged from a common pool of embryonic DRG neurons that are marked by the expression of the neurotrophin receptor TrkA. Here we discuss how intrinsic transcription factors interface with target-derived signals to specify these functionally distinct sensory neurons. We will also discuss how this control mechanism provides a developmental perspective for the coding of somatic sensations.
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Affiliation(s)
- Yang Liu
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115, USA
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429
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Cao X, Mercaldo V, Li P, Wu LJ, Zhuo M. Facilitation of the inhibitory transmission by gastrin-releasing peptide in the anterior cingulate cortex. Mol Pain 2010; 6:52. [PMID: 20836873 PMCID: PMC2945970 DOI: 10.1186/1744-8069-6-52] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/13/2010] [Indexed: 12/22/2022] Open
Abstract
Gastrin-releasing peptide (GRP) has been proposed as a peptidergic molecule for behavioral fear and itching. Immunohistochemistry and in situ hybridization studies have shown that GRP and GRP receptor are widely distributed in forebrain areas. Less information is available for the functional action for GRP in the prefrontal cortex including the anterior cingulate cortex (ACC). Here we used whole-cell patch-clamp recording technique to study the modulation of synaptic transmission by GRP in the ACC. We found that GRP increased the frequency of sIPSCs recorded while had no significant effect on sEPSCs in ACC pyramidal neurons. The facilitatory effect of GRP on sIPSCs was blocked by the GRP receptor antagonist, RC3095. In the presence of TTX, however, GRP had no effect on the mIPSCs. Therefore, activation of GRP receptor may facilitate the excitation of the interneurons and enhanced spontaneous GABAergic, but not glutamatergic neurotransmission. Similar results on GRP modulation of GABAergic transmission were observed in the insular cortex and amygdala, suggesting a general possible effect of GRP on cortical inhibitory transmission. Our results suggest that GRP receptor is an important regulator of inhibitory circuits in forebrain areas.
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Affiliation(s)
- XiaoYan Cao
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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430
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Premkumar LS. Targeting TRPV1 as an alternative approach to narcotic analgesics to treat chronic pain conditions. AAPS J 2010; 12:361-70. [PMID: 20440589 PMCID: PMC2895451 DOI: 10.1208/s12248-010-9196-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 04/19/2010] [Indexed: 12/24/2022] Open
Abstract
In spite of intense research efforts and after the dedicated Decade of Pain Control and Research, there are not many alternatives to opioid-based narcotic analgesics in the therapeutic armamentarium to treat chronic pain conditions. Chronic opioid treatment is associated with sedation, tolerance, dependence, hyperalgesia, respiratory depression, and constipation. Since the affective component is an integral part of pain perception, perhaps it is inevitable that potent analgesics possess the property of impacting pain pathways in the supraspinal structures. The question still remains to be answered is that whether a powerful analgesic can be devoid of narcotic effect and addictive potentials. Local anesthetics are powerful analgesics for acute pain by blocking voltage-gated sodium channels that are involved in generation and propagation of action potentials. Antidepressants and anticonvulsants have proven to be useful in the treatment of certain modalities of pain. In neuropathic pain conditions, the complexity arises because of the notion that neuronal circuitry is altered, as occurs in phantom pain, in that pain is perceived even in the absence of peripheral nociceptive inputs. If the locus of these changes is in the central nervous system, commonly used analgesics may not be very useful. This review focuses on the recent advances in nociceptive transmission and nociceptive transient receptor potential vanilloid 1 channel as a target for treating chronic pain conditions with its agonists/antagonists.
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Affiliation(s)
- Louis S Premkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702, USA.
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431
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Kremer AE, Martens JJWW, Kulik W, Ruëff F, Kuiper EMM, van Buuren HR, van Erpecum KJ, Kondrackiene J, Prieto J, Rust C, Geenes VL, Williamson C, Moolenaar WH, Beuers U, Oude Elferink RPJ. Lysophosphatidic acid is a potential mediator of cholestatic pruritus. Gastroenterology 2010; 139:1008-18, 1018.e1. [PMID: 20546739 DOI: 10.1053/j.gastro.2010.05.009] [Citation(s) in RCA: 269] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Revised: 04/04/2010] [Accepted: 05/11/2010] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Pruritus is a common and disabling symptom in cholestatic disorders. However, its causes remain unknown. We hypothesized that potential pruritogens accumulate in the circulation of cholestatic patients and activate sensory neurons. METHODS Cytosolic free calcium ([Ca(2+)](i)) was measured in neuronal cell lines by ratiometric fluorometry upon exposure to serum samples from pruritic patients with intrahepatic cholestasis of pregnancy (ICP), primary biliary cirrhosis (PBC), other cholestatic disorders, and pregnant, healthy, and nonpruritic disease controls. Putative [Ca(2+)](i)-inducing factors in pruritic serum were explored by analytical techniques, including quantification by high-performance liquid chromatography/mass spectroscopy. In mice, scratch activity after intradermal pruritogen injection was quantified using a magnetic device. RESULTS Transient increases in neuronal [Ca(2+)](i) induced by pruritic PBC and ICP sera were higher than corresponding controls. Lysophosphatidic acid (LPA) could be identified as a major [Ca(2+)](i) agonist in pruritic sera, and LPA concentrations were increased in cholestatic patients with pruritus. LPA injected intradermally into mice induced scratch responses. Autotaxin, the serum enzyme converting lysophosphatidylcholine into LPA, was markedly increased in patients with ICP versus pregnant controls (P < .0001) and cholestatic patients with versus without pruritus (P < .0001). Autotaxin activity correlated with intensity of pruritus (P < .0001), which was not the case for serum bile salts, histamine, tryptase, substance P, or mu-opioids. In patients with PBC who underwent temporary nasobiliary drainage, both itch intensity and autotaxin activity markedly decreased during drainage and returned to preexistent levels after drain removal. CONCLUSIONS We suggest that LPA and autotaxin play a critical role in cholestatic pruritus and may serve as potential targets for future therapeutic interventions.
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Affiliation(s)
- Andreas E Kremer
- Tytgat Institute for Liver and Intestinal Research, University of Amsterdam, Amsterdam, The Netherlands.
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432
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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.
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Affiliation(s)
- T Akiyama
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, USA
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433
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434
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Abstract
Pruritus (itch) is a major characteristic and one of the most debilitating symptoms in allergic and atopic diseases and the diagnostic hallmark of atopic dermatitis. Pruritus is regularly defined as an unpleasant sensation provoking the desire to scratch. Although we achieved rather good knowledge about certain inducers of itch such as neuropeptides, amines, mu-opioids, cytokines and proteases, for example, less is known about the pathophysiological specifities among the different diseases, and the therapeutic consequences which may derive thereoff. This review dissects the role of mediators, receptors and itch inhibitors on peripheral nerve endings, dorsal root ganglia, the spinal cord and the CNS leading to the amplification or - vice versa - suppression of pruritus. As the treatment of pruritus in allergic and atopic skin disease is still not satisfactory, knowing these pathways and mechanisms may lead to novel therapeutic approaches against this frequently encountered skin symptom.
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Affiliation(s)
- J Buddenkotte
- Deparment of Dermatology, Boltzmann Institute for Cell- and Immunobiology of Skin, University Hospital Münster, Münster, Germany
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435
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Xu S, Ono K, Inenaga K. Electrophysiological and chemical properties in subclassified acutely dissociated cells of rat trigeminal ganglion by current signatures. J Neurophysiol 2010; 104:3451-61. [PMID: 20573966 DOI: 10.1152/jn.00336.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In the present study, we subclassified acutely dissociated trigeminal ganglion (TRG) cells of rats using a current signature method in whole cell patch-clamp recordings. Using modified criteria for cell classification for the dorsal root ganglion (DRG), TRG cells were subclassified into nine cell types: 1-5, 7-9, and 13. Types 1, 3, and 7 were in the small cell groups (15-24 μm); types 4, 5, and 8-13 were in the medium cell groups (25-38 μm); and type 2 was a mixed group of both cell sizes. Types 1-3, 5, and 7 showed high-input resistance and types 1, 2, and 7 showed more depolarized resting membrane potentials. Types 1, 2, and 5-13 expressed long-duration action potentials (APs), but types 3 and 4 expressed short-duration APs. Sensitivities to capsaicin, protons, and adenosine 5'-triphosphate (ATP) in TRG cell types largely corresponded to DRG cell types. However, different from the matched DRG types, half of TRG type 1 cells were capsaicin insensitive, showing desensitizing proton-induced currents, and types 5, 7, and 9 exhibited slow-desensitizing ATP-induced currents. Types 4, 5, and 8-13 had nicotine sensitivity, but the other cell types were insensitive. These results indicate that the "current signatures" classification is a useful means to separate TRG cells into internally homogeneous subpopulations that were distinct from other cell types. Furthermore, the data suggest some specific differences in the chemical responsiveness of some cell types between the TRG and DRG.
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Affiliation(s)
- Shenghong Xu
- Kyushu Dental College, Department of Biosciences, 2-6-1, Manazuru, Kokurakitaku, Kitakyushu, 803-8580, Japan
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436
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Smith ESJ, Blass GRC, Lewin GR, Park TJ. Absence of histamine-induced itch in the African naked mole-rat and "rescue" by Substance P. Mol Pain 2010; 6:29. [PMID: 20497578 PMCID: PMC2886013 DOI: 10.1186/1744-8069-6-29] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 05/24/2010] [Indexed: 11/17/2022] Open
Abstract
Recent research has proposed a pathway in which sensory neurons expressing the capsaicin activated ion channel TRPV1 are required for histamine-induced itch and subsequent scratching behavior. We examined histamine-induced itch in the African naked mole-rat (Heterocephalus glaber) and found that although naked mole-rats display innate scratching behavior, histamine was unable to evoke increased scratching as is observed in most mouse strains. Using calcium imaging, we examined the histamine sensitivity of naked mole-rat dorsal root ganglia (DRG) neurons and identified a population of small diameter neurons activated by histamine, the majority of which are also capsaicin-sensitive. This suggested that naked mole-rat sensory neurons are activated by histamine, but that spinal dorsal horn processing of sensory information is not the same as in other rodents. We have previously shown that naked mole-rats naturally lack substance P (SP) in cutaneous C-fibers, but that the neurokinin-1 receptor is expressed in the superficial spinal cord. This led us to investigate if SP deficiency plays a role in the lack of histamine-induced scratching in this species. After intrathecal administration of SP into the spinal cord we observed robust scratching behavior in response to histamine injection. Our data therefore support a model in which TRPV1-expressing sensory neurons are important for histamine-induced itch. In addition, we demonstrate a requirement for active, SP-induced post-synaptic drive to enable histamine sensitive afferents to drive itch-related behavior in the naked mole-rat. These results illustrate that it is altered dorsal horn connectivity of nociceptors that underlies the lack of itch and pain-related behavior in the naked mole-rat.
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Affiliation(s)
- Ewan St John Smith
- Department of Neuroscience, Max-Delbruck Center for Molecular Medicine, Robert-Rossle-Strasse 10, 13125 Berlin-Buch, Germany
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437
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Yosipovitch G. Recent advances in pruritus - what we have learned and where are we headed. F1000 MEDICINE REPORTS 2010; 2. [PMID: 20948846 PMCID: PMC2950052 DOI: 10.3410/m2-39] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Chronic pruritus is an emerging health problem with a significant impact on quality of life. Recent advances in our understanding of newly discovered pathways and receptors for itch have been made. It is hoped that recent advancements will also drive the development of novel therapies for this often-neglected and bothersome symptom.
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Affiliation(s)
- Gil Yosipovitch
- Department of Dermatology, Wake Forest University Health Sciences, Medical Center Boulevard Winston-Salem, NC 27157 USA
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438
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Abstract
Itch is thought to be signaled by pruritogen-responsive neurons in the superficial spinal dorsal horn. Many neurons here express the substance P NK-1 receptor. We investigated whether neurotoxic destruction of spinal NK-1-expressing neurons affected itch-related scratching behavior. Rats received intracisternal substance P conjugated to saporin (SP-SAP), or saporin (SAP) only (controls), and were subsequently tested for scratching behavior elicited by intradermal 5-hydroxytryptamine. SAP controls exhibited dose-related hindlimb scratching, which was significantly attenuated in SP-SAP-treated rats. There was a virtual absence of NK-1 immunoreactive neurons in superficial laminae of the upper cervical and medullary dorsal horn in SP-SAP-treated rats. These results indicate that superficial dorsal horn neurons expressing NK-1 receptors play a key role in spinal itch transmission.
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439
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Ross SE, Mardinly AR, McCord AE, Zurawski J, Cohen S, Jung C, Hu L, Mok SI, Shah A, Savner E, Tolias C, Corfas R, Chen S, Inquimbert P, Xu Y, McInnes RR, Rice FL, Corfas G, Ma Q, Woolf CJ, Greenberg ME. Loss of inhibitory interneurons in the dorsal spinal cord and elevated itch in Bhlhb5 mutant mice. Neuron 2010; 65:886-98. [PMID: 20346763 PMCID: PMC2856621 DOI: 10.1016/j.neuron.2010.02.025] [Citation(s) in RCA: 325] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2010] [Indexed: 12/21/2022]
Abstract
Itch is the least well understood of all the somatic senses, and the neural circuits that underlie this sensation are poorly defined. Here we show that the atonal-related transcription factor Bhlhb5 is transiently expressed in the dorsal horn of the developing spinal cord and appears to play a role in the formation and regulation of pruritic (itch) circuits. Mice lacking Bhlhb5 develop self-inflicted skin lesions and show significantly enhanced scratching responses to pruritic agents. Through genetic fate-mapping and conditional ablation, we provide evidence that the pruritic phenotype in Bhlhb5 mutants is due to selective loss of a subset of inhibitory interneurons in the dorsal horn. Our findings suggest that Bhlhb5 is required for the survival of a specific population of inhibitory interneurons that regulate pruritus, and provide evidence that the loss of inhibitory synaptic input results in abnormal itch.
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Affiliation(s)
- Sarah E. Ross
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Alan R. Mardinly
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Alejandra E. McCord
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Jonathan Zurawski
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Sonia Cohen
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Cynthia Jung
- Programs in Developmental Biology, and Genetics and the Department of Molecular Genetics, The Research Institute, Hospital for Sick Children, 555 University Ave., Toronto, Ontario, M5G 1X8, Canada
| | - Linda Hu
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Stephanie I. Mok
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Anar Shah
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Erin Savner
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Christos Tolias
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Roman Corfas
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Suzhen Chen
- F. M. Kirby Neurobiology Center, Children's Hospital, and Departments of Neurology and Neurobiology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Perrine Inquimbert
- F. M. Kirby Neurobiology Center, Children's Hospital, and Departments of Neurology and Neurobiology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Yi Xu
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115, USA
| | - Roderick R. McInnes
- Programs in Developmental Biology, and Genetics and the Department of Molecular Genetics, The Research Institute, Hospital for Sick Children, 555 University Ave., Toronto, Ontario, M5G 1X8, Canada
- Department of Pediatrics and the Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Frank L. Rice
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY, 12208 and Integrated Tissue Dynamics LL, Renssalaer, NY 12144, USA
| | - Gabriel Corfas
- F. M. Kirby Neurobiology Center, Children's Hospital, and Departments of Neurology and Neurobiology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Qiufu Ma
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115, USA
| | - Clifford J. Woolf
- F. M. Kirby Neurobiology Center, Children's Hospital, and Departments of Neurology and Neurobiology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Michael E. Greenberg
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA
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440
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Abstract
The itch sensation results from the excitation of primary sensory nerve endings in the skin, but the underlying molecular mechanisms are not completely understood. Liu et al. (2009) now report that some members of the Mrgpr class of G protein-coupled receptors mediate the itch caused by the antimalarial drug chloroquine.
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Affiliation(s)
- Michael Bandell
- Genomics Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
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441
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Is That Itch Really a Pain? Nurse Educ 2010; 35:36. [DOI: 10.1097/01.nne.0000334839.29200.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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442
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Boguniewicz M, Leung DYM. Recent insights into atopic dermatitis and implications for management of infectious complications. J Allergy Clin Immunol 2010; 125:4-13; quiz 14-5. [PMID: 20109729 PMCID: PMC2814072 DOI: 10.1016/j.jaci.2009.11.027] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 11/19/2009] [Accepted: 11/19/2009] [Indexed: 01/30/2023]
Abstract
Atopic dermatitis (AD) is a common complex disease that frequently follows a chronic relapsing course and affects the quality of life of patients and families in a significant manner. New insights into the pathophysiology of AD point to an important role of structural abnormalities in the epidermis combined with immune dysregulation. Patients with AD have a unique predisposition to colonization or infection by a number of microbial organisms, most notably Staphylococcus aureus and herpes simplex virus. A multipronged approach directed at healing or protecting the skin barrier and addressing the immune dysregulation is necessary to improve the likelihood of successful outcomes.
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Affiliation(s)
- Mark Boguniewicz
- Division of Pediatric Allergy-Immunology, Department of Pediatrics, National Jewish Health and University of Colorado School of Medicine, 1400 Jackson St, Rm J310, Denver, CO 80206, USA.
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443
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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.
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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
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444
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445
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Buchen L. The itch without the pain. Nature 2009. [DOI: 10.1038/news.2009.802] [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]
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