title: Neural processing of itch.
abstract: While considerable effort has been made to investigate the neural mechanisms of pain, much less effort has been devoted to itch, at least until recently. However, itch is now gaining increasing recognition as a widespread and costly medical and socioeconomic issue. This is accompanied by increasing interest in the underlying neural mechanisms of itch, which has become a vibrant and rapidly-advancing field of research. The goal of the present forefront review is to describe the recent progress that has been made in our understanding of itch mechanisms.
authors.affiliation: University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, United States.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Akiyama
authors.forename: E
authors.initials: E
authors.lastname: Carstens
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D004195:Disease Models, Animal; D055724:Electrophysiological Phenomena / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007395:Interneurons / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D011537:Pruritus / Q000139:chemically induced / Q000503:physiopathology*; D015398:Signal Transduction / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D014276:Trigeminal Nerve / Q000503:physiopathology
chemical_list: D000701:Analgesics, Opioid; D018377:Neurotransmitter Agents
keywords: 5-HT; 5-HT receptor subtype 2; 5-HT2; 5-hydroxytryptamine (serotonin); AITC; BAM8–22; BLT; DRG; ET-1; ETA-1; G protein-coupled bile acid receptor 1 (GPBAR1); GRP; GRPR; Gastrin-releasing peptide; Gastrin-releasing peptide receptor; H1R; IB4; IL-31; Interleukin 31; K2P; Kv; LPA; LT; LTB4; LTB4 receptor; LTMRs; LTP; MI; MOR1D; Mas-related G-protein-coupled receptor; Mrgpr; NGF; NK-1; NS; Nppb; Npra; OSMR; PAF; PAG; PAR; Platelet-activating factor; Rho-ROCK; Rho-associated protein kinase; SP; SPC; STT; TGR5; TLR3; TLR7; TR4; TRPA1; TRPV1; TXA2; VGLUT2; Vc; WDR; allyl isothiocyanate; bovine adrenal medullary peptide 8–22; dorsal root ganglion; endothelin receptor A-1; endothelin-1; histamine receptor-1; isolectin B4; itch; leukotriene B4; long-term potentiation; low threshold; low-threshold mechanoreceptors; lysophosphatidic acid; mechanically insensitive; morphine receptor-1D isoform; natriuretic peptide receptor A; natriuretic polypeptide B; nerve growth factor; neurokinin-1 receptor; nociceptive specific; oncostatin M receptor; periaqueductal gray; protease-activated receptor; pruritogens; pruritus; scratching behavior; sphingosylphosphorylcholine; spinal cord; spinothalamic tract; substance P; testicular orphan nuclear receptor-4; thromboxane A2; toll-like receptor 3; toll-like receptor 7; transient receptor potential ankyrin 1; transient receptor potential vanilloid 1; trigeminal caudalis; trigeminal subnucleus caudalis; two-pore-domain potassium channels; vesicular glutamate transporter-2; voltage-gated potassium channel; wide dynamic range
references.citation: J Neurophysiol. 2002 Mar;87(3):1280-9
references.pmid: 11877502
references.citation: Science. 2013 May 24;340(6135):968-71
references.pmid: 23704570
references.citation: Ann Allergy Asthma Immunol. 2007 Feb;98(2):182-4
references.pmid: 17304888
references.citation: Nat Immunol. 2004 Jul;5(7):752-60
references.pmid: 15184896
references.citation: Nat Neurosci. 2013 Feb;16(2):117-8
references.pmid: 23354383
references.citation: J Neurophysiol. 2003 May;89(5):2441-8
references.pmid: 12611975
references.citation: J Clin Invest. 2010 Nov;120(11):3779-87
references.pmid: 21041960
references.citation: Nat Med. 2000 Feb;6(2):151-8
references.pmid: 10655102
references.citation: J Neurophysiol. 2011 Sep;106(3):1078-88
references.pmid: 21653727
references.citation: Acta Derm Venereol. 2008;88(1):34-7
references.pmid: 18176748
references.citation: J Invest Dermatol. 2013 Jan;133(1):268-70
references.pmid: 22832487
references.citation: Mol Pain. 2012 Jul 09;8:52
references.pmid: 22776446
references.citation: Eur J Neurosci. 2012 Aug;36(3):2311-6
references.pmid: 22626250
references.citation: Br J Dermatol. 2002 May;146(5):792-800
references.pmid: 12000375
references.citation: J Pharmacol Exp Ther. 1998 Sep;286(3):1140-5
references.pmid: 9732370
references.citation: J Clin Invest. 2010 Nov;120(11):3773-8
references.pmid: 21041959
references.citation: J Neurosci Methods. 2012 Oct 15;211(1):1-10
references.pmid: 22971351
references.citation: Science. 2009 Sep 18;325(5947):1531-4
references.pmid: 19661382
references.citation: Mol Pain. 2012 Jan 11;8:2
references.pmid: 22233604
references.citation: Cell. 2001 Sep 7;106(5):619-32
references.pmid: 11551509
references.citation: Nature. 1978 Apr 27;272(5656):826-7
references.pmid: 347307
references.citation: Neuron. 2013 Apr 24;78(2):312-24
references.pmid: 23622066
references.citation: Neurosci Lett. 2010 Feb 19;470(3):193-6
references.pmid: 19576959
references.citation: J Burn Care Res. 2012 May-Jun;33(3):407-18
references.pmid: 22210065
references.citation: J Neurosci. 2012 Jun 20;32(25):8686-95
references.pmid: 22723708
references.citation: Pain. 2010 Nov;151(2):378-383
references.pmid: 20709455
references.citation: J Invest Dermatol. 2013 Oct;133(10):2489-2492
references.pmid: 23558404
references.citation: Proc Natl Acad Sci U S A. 2009 Jul 7;106(27):11330-5
references.pmid: 19564617
references.citation: Pain. 1993 Jun;53(3):323-334
references.pmid: 8351161
references.citation: J Pharmacol Sci. 2011;115(3):417-20
references.pmid: 21372505
references.citation: Nat Neurosci. 2013 Jul;16(7):910-8
references.pmid: 23685721
references.citation: Br J Dermatol. 1997 Sep;137(3):415-7
references.pmid: 9349340
references.citation: J Am Acad Dermatol. 2004 Jan;50(1):33-40
references.pmid: 14699362
references.citation: Skin Pharmacol Appl Skin Physiol. 2003 May-Jun;16(3):165-75
references.pmid: 12677097
references.citation: PLoS One. 2012;7(5):e36355
references.pmid: 22563493
references.citation: J Neurophysiol. 2011 Jun;105(6):2811-7
references.pmid: 21430273
references.citation: Acta Derm Venereol. 2013 Sep 4;93(5):532-7
references.pmid: 23450324
references.citation: Eur J Pharmacol. 1998 Jul 17;353(1):93-6
references.pmid: 9721045
references.citation: Neuroreport. 2010 Mar 10;21(4):303-8
references.pmid: 20125052
references.citation: Exp Dermatol. 2009 Jan;18(1):57-63
references.pmid: 18647342
references.citation: Neurosci Lett. 2010 Oct 22;484(1):62-5
references.pmid: 20709155
references.citation: J Biol Chem. 2013 May 3;288(18):12818-27
references.pmid: 23508958
references.citation: Proc Natl Acad Sci U S A. 2011 Feb 1;108(5):2100-5
references.pmid: 21252304
references.citation: Neurosci Res. 1999 Nov;35(2):77-83
references.pmid: 10616911
references.citation: Int J Dermatol. 2002 Apr;41(4):212-6
references.pmid: 12031029
references.citation: J Neurophysiol. 1991 Jul;66(1):228-46
references.pmid: 1919669
references.citation: Gen Hosp Psychiatry. 2008 Jul-Aug;30(4):344-8
references.pmid: 18585538
references.citation: J Neurosci. 2002 May 15;22(10):4103-13
references.pmid: 12019329
references.citation: Eur J Pharmacol. 2012 Jul 5;686(1-3):16-21
references.pmid: 22546226
references.citation: J Physiol. 2007 Oct 15;584(Pt 2):521-33
references.pmid: 17717012
references.citation: Br J Dermatol. 2000 Nov;143(5):969-73
references.pmid: 11069504
references.citation: Expert Opin Pharmacother. 2010 Jul;11(10):1673-82
references.pmid: 20426711
references.citation: Exp Physiol. 2002 Mar;87(2):245-9
references.pmid: 11856970
references.citation: Mol Pain. 2011 May 15;7:36
references.pmid: 21569622
references.citation: Brain Res Rev. 2009 Apr;60(1):214-25
references.pmid: 19146877
references.citation: J Neurosci. 2009 May 20;29(20):6691-9
references.pmid: 19458238
references.citation: Nature. 1983 Nov 17-23;306(5940):264-5
references.pmid: 6646208
references.citation: Neurology. 2003 Aug 26;61(4):564-6
references.pmid: 12939442
references.citation: Acta Derm Venereol. 2008;88(2):128-31
references.pmid: 18311438
references.citation: PLoS One. 2011;6(5):e20559
references.pmid: 21655234
references.citation: Proc Natl Acad Sci U S A. 2012 Jan 10;109(2):547-52
references.pmid: 22203955
references.citation: Dermatol Clin. 2010 Jul;28(3):467-78
references.pmid: 20510757
references.citation: Neuron. 2005 Jan 6;45(1):17-25
references.pmid: 15629699
references.citation: J Neurosci. 2009 Jan 21;29(3):686-95
references.pmid: 19158295
references.citation: Pain. 1997 May;71(1):49-55
references.pmid: 9200173
references.citation: Neurosci Lett. 2011 Apr 4;492(3):175-8
references.pmid: 21315802
references.citation: Neurosci Lett. 2004 May 6;361(1-3):79-82
references.pmid: 15135898
references.citation: J Neurophysiol. 2009 Oct;102(4):2176-83
references.pmid: 19625538
references.citation: Brain Res Mol Brain Res. 2005 Jun 13;137(1-2):263-6
references.pmid: 15950785
references.citation: J Invest Dermatol. 2011 Mar;131(3):613-22
references.pmid: 21191404
references.citation: J Clin Invest. 2012 Jun;122(6):2195-207
references.pmid: 22565312
references.citation: Biomed Instrum Technol. 1991 Sep-Oct;25(5):400-3
references.pmid: 1933091
references.citation: Proc Natl Acad Sci U S A. 2009 Jun 2;106(22):9075-80
references.pmid: 19451647
references.citation: J Allergy Clin Immunol. 1997 May;99(5):640-7
references.pmid: 9155831
references.citation: Eur J Pain. 2006 Jul;10(5):473-8
references.pmid: 16678456
references.citation: J Neurosci. 2008 Mar 5;28(10):2485-94
references.pmid: 18322093
references.citation: J Neurophysiol. 2013 Feb;109(3):742-8
references.pmid: 23155177
references.citation: Somatosens Mot Res. 1999;16(4):291-8
references.pmid: 10632026
references.citation: J Neurophysiol. 2010 Nov;104(5):2442-50
references.pmid: 20739601
references.citation: Percept Psychophys. 1990 Jul;48(1):12-8
references.pmid: 2165586
references.citation: J Neurophysiol. 1978 Jul;41(4):933-47
references.pmid: 98615
references.citation: Pharmacology. 2004 Sep;72(1):51-6
references.pmid: 15292655
references.citation: Dig Liver Dis. 2000 Oct;32(7):621-5
references.pmid: 11142563
references.citation: J Cardiovasc Pharmacol. 1989;13 Suppl 5:S220-2
references.pmid: 2473319
references.citation: Am J Nephrol. 2012;36(2):175-83
references.pmid: 22868684
references.citation: J Pharmacol Exp Ther. 2011 Jun;337(3):822-9
references.pmid: 21421741
references.citation: Sci Signal. 2011 Jul 12;4(181):ra45
references.pmid: 21775281
references.citation: Pain. 1997 Nov;73(2):239-243
references.pmid: 9415511
references.citation: J Invest Dermatol. 2012 Jul;132(7):1886-91
references.pmid: 22418875
references.citation: J Pain. 2003 Aug;4(6):338-43
references.pmid: 14622691
references.citation: PLoS One. 2011;6(7):e22665
references.pmid: 21818363
references.citation: J Neurophysiol. 1997 May;77(5):2499-514
references.pmid: 9163372
references.citation: J Invest Dermatol. 1982 Dec;79(6):368-73
references.pmid: 7142737
references.citation: J Neurosci. 2007 Jul 11;27(28):7490-7
references.pmid: 17626210
references.citation: Nature. 2007 Aug 9;448(7154):700-3
references.pmid: 17653196
references.citation: J Neurosci. 2009 Jul 1;29(26):8612-9
references.pmid: 19571152
references.citation: Pain. 1996 Jan;64(1):129-138
references.pmid: 8867255
references.citation: Cell. 2009 Oct 16;139(2):267-84
references.pmid: 19837031
references.citation: Neuron. 2010 Nov 4;68(3):543-56
references.pmid: 21040853
references.citation: Cell. 2009 Dec 24;139(7):1353-65
references.pmid: 20004959
references.citation: Life Sci. 2012 Oct 15;91(13-14):628-33
references.pmid: 22483687
references.citation: J Neurosci. 2013 Apr 3;33(14):6093-101
references.pmid: 23554490
references.citation: Br J Dermatol. 2004 Sep;151(3):594-9
references.pmid: 15377345
references.citation: Proc Natl Acad Sci U S A. 2011 Feb 22;108(8):3371-6
references.pmid: 21300878
references.citation: Nat Neurosci. 2013 Feb;16(2):174-82
references.pmid: 23263443
references.citation: J Neurosci. 2011 Oct 19;31(42):14841-9
references.pmid: 22016517
references.citation: Science. 1955 Sep 9;122(3167):469-70
references.pmid: 13255877
references.citation: J Invest Dermatol. 1978 Oct;71(4):233-5
references.pmid: 81243
references.citation: Pain. 2006 Dec 15;126(1-3):16-23
references.pmid: 16842920
references.citation: Nat Neurosci. 2010 Dec;13(12):1460-2
references.pmid: 21037581
references.citation: Pain. 2007 Sep;131(1-2):4-7
references.pmid: 17524558
references.citation: Eur J Pharmacol. 2002 Jan 25;435(2-3):259-64
references.pmid: 11821035
references.citation: Neuron. 2010 Nov 4;68(3):529-42
references.pmid: 21040852
references.citation: J Neurophysiol. 1994 Mar;71(3):981-1002
references.pmid: 8201437
references.citation: J Neurosci. 2012 Oct 17;32(42):14532-7
references.pmid: 23077038
references.citation: Pain. 2007 Nov;132(1-2):67-73
references.pmid: 17350763
references.citation: Neurosci Bull. 2012 Apr;28(2):145-54
references.pmid: 22466125
references.citation: J Neurosci. 1997 Oct 15;17(20):8003-8
references.pmid: 9315918
references.citation: J Invest Dermatol. 2007 Aug;127(8):2042-7
references.pmid: 17429442
references.citation: J Neurosci. 2003 Jul 16;23(15):6176-80
references.pmid: 12867500
references.citation: Mol Brain. 2012 Jan 24;5:3
references.pmid: 22272772
references.citation: J Neurosci. 2007 Sep 12;27(37):10007-14
references.pmid: 17855615
references.citation: Acta Derm Venereol. 1985;65(5):409-12
references.pmid: 2416164
references.citation: J Neurosci Methods. 2003 Jun 30;126(2):137-43
references.pmid: 12814838
references.citation: J Neurosci. 2009 Oct 21;29(42):13202-9
references.pmid: 19846708
references.citation: Br J Pharmacol. 2003 Jan;138(1):202-8
references.pmid: 12522091
references.citation: J Neurophysiol. 2012 Sep;108(6):1711-23
references.pmid: 22723676
references.citation: Acta Derm Venereol. 2007;87(4):291-4
references.pmid: 17598029
references.citation: J Neurophysiol. 2004 Jan;91(1):213-22
references.pmid: 14715718
references.citation: Neuropharmacology. 2012 Sep;63(4):743-9
references.pmid: 22683515
references.citation: Peptides. 2011 Oct;32(10):2098-103
references.pmid: 21933692
references.citation: J Neurosci Methods. 2005 Mar 15;142(1):107-14
references.pmid: 15652623
references.citation: Eur J Neurosci. 2003 Jan;17(1):13-27
references.pmid: 12534965
references.citation: J Invest Dermatol. 2009 Dec;129(12):2901-5
references.pmid: 19571818
references.citation: Inflamm Res. 1997 Oct;46(10):412-6
references.pmid: 9372314
references.citation: J Invest Dermatol. 2013 Jun;133(6):1673-5
references.pmid: 23353988
references.citation: Chem Immunol Allergy. 2012;98:253-65
references.pmid: 22767068
references.citation: Pain. 2003 Sep;105(1-2):339-46
references.pmid: 14499452
references.citation: Cell. 2008 May 2;133(3):475-85
references.pmid: 18455988
references.citation: J Neurosci. 2011 May 18;31(20):7563-7
references.pmid: 21593341
references.citation: Brain Res. 1991 Aug 2;555(2):181-92
references.pmid: 1933332
references.citation: Afr J Med Med Sci. 1994 Jun;23(2):139-42
references.pmid: 7625301
references.citation: Mol Pain. 2011 Jun 24;7:47
references.pmid: 21699733
references.citation: Nat Rev Neurosci. 2001 Feb;2(2):83-91
references.pmid: 11252998
references.citation: J Allergy Clin Immunol. 2006 Feb;117(2):411-7
references.pmid: 16461142
references.citation: Neuron. 2010 Mar 25;65(6):886-98
references.pmid: 20346763
references.citation: Exp Dermatol. 2011 Oct;20(10):778-82
references.pmid: 21929688
references.citation: Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10385-90
references.pmid: 10468617
references.citation: Obstet Gynecol. 2005 Sep;106(3):639; author reply 639
references.pmid: 16135600
references.citation: Acta Derm Venereol. 2001 Aug-Sep;81(4):250-4
references.pmid: 11720170
references.citation: Pain. 2008 Oct 31;139(3):681-687
references.pmid: 18789837
references.citation: Pain. 2009 Jul;144(1-2):66-75
references.pmid: 19423224
references.citation: J Neurophysiol. 1991 Jul;66(1):190-211
references.pmid: 1919666
references.citation: Acta Odontol Scand. 2009;67(2):99-105
references.pmid: 19137455
references.citation: Br J Pharmacol. 2008 Jul;154(5):1073-8
references.pmid: 18536755
references.citation: Eur J Pharmacol. 1999 Feb 19;367(2-3):361-71
references.pmid: 10079012
references.citation: Life Sci. 2006 Oct 26;79(22):2144-50
references.pmid: 16914167
references.citation: Semin Cutan Med Surg. 2011 Jun;30(2):127-37
references.pmid: 21767775
references.citation: J Burn Care Res. 2013 Jan-Feb;34(1):94-101
references.pmid: 23079565
references.citation: Eur J Pharmacol. 2007 Jan 5;554(1):30-3
references.pmid: 17112507
references.citation: Pain. 2004 May;109(1-2):4-7
references.pmid: 15082120
references.citation: Exp Dermatol. 2011 Nov;20(11):894-8
references.pmid: 21824199
references.citation: J Dermatol Sci. 2007 Nov;48(2):103-11
references.pmid: 17643268
references.citation: Proc Natl Acad Sci U S A. 2008 Dec 16;105(50):20004-8
references.pmid: 19066214
references.citation: Acta Derm Venereol. 2011 Jan;91(1):18-23
references.pmid: 21103852
references.citation: J Lipid Res. 2003 Jan;44(1):93-102
references.pmid: 12518027
references.citation: J Invest Dermatol. 2001 Dec;117(6):1621-6
references.pmid: 11886531
references.citation: J Pharmacol Toxicol Methods. 2000 Nov-Dec;44(3):453-9
references.pmid: 11395322
references.citation: Nat Neurosci. 2011 May;14(5):595-602
references.pmid: 21460831
references.citation: Neuroscience. 2012 Dec 13;226:305-12
references.pmid: 23000623
references.citation: QJM. 2003 Jan;96(1):7-26
references.pmid: 12509645
references.citation: Neuron. 2013 Apr 10;78(1):138-51
references.pmid: 23523592
references.citation: Exp Physiol. 2000 Nov;85(6):839-46
references.pmid: 11187978
references.citation: J Pharmacol Exp Ther. 2003 Apr;305(1):173-9
references.pmid: 12649366
references.citation: Trends Neurosci. 1992 Dec;15(12):497-501
references.pmid: 1282750
references.citation: Eur J Pharmacol. 2006 Jan 13;530(1-2):172-8
references.pmid: 16359660
references.citation: J Neurosci. 2008 Jul 23;28(30):7659-69
references.pmid: 18650342
references.citation: J Am Acad Dermatol. 2002 Aug;47(2):245-50
references.pmid: 12140471
references.citation: Mol Pain. 2012 Sep 10;8:64
references.pmid: 22963197
references.citation: Clin Cosmet Investig Dermatol. 2009 Feb 19;2:9-13
references.pmid: 21436964
references.citation: Nat Neurosci. 2009 May;12(5):544-6
references.pmid: 19349977
references.citation: J Clin Invest. 2013 Apr;123(4):1513-30
references.pmid: 23524965
references.citation: Cell. 2011 Oct 14;147(2):447-58
references.pmid: 22000021
references.citation: Nephrol Dial Transplant. 2006 Dec;21(12):3495-505
references.pmid: 16968725
references.citation: Acta Derm Venereol. 2012 Sep;92(5):515-20
references.pmid: 22513524
references.citation: Arch Int Pharmacodyn Ther. 1992 Jan-Feb;315:96-109
references.pmid: 1417367
references.citation: J Clin Invest. 2010 Nov;120(11):3760-72
references.pmid: 21041958
references.citation: J Neurophysiol. 2008 Apr;99(4):1581-9
references.pmid: 18234974
references.citation: Acta Derm Venereol. 2010 Nov;90(6):575-81
references.pmid: 21057739
references.citation: J Invest Dermatol. 2009 Dec;129(12):2854-60
references.pmid: 19657356
references.citation: Brain Res. 1992 Jul 3;584(1-2):163-8
references.pmid: 1515936
references.citation: Eur J Pharmacol. 2008 Mar 31;583(1):92-6
references.pmid: 18289521
references.citation: J Neurophysiol. 2008 Oct;100(4):2062-9
references.pmid: 18562548
references.citation: Acta Derm Venereol. 2009;89(4):379-83
references.pmid: 19688150
references.citation: J Invest Dermatol. 2018 Feb;138(2):461-464
references.pmid: 28988117
references.citation: Neuron. 2006 Nov 22;52(4):691-703
references.pmid: 17114052
references.citation: Neurosci Lett. 2003 Mar 13;339(1):72-6
references.pmid: 12618303
references.citation: Br J Pharmacol. 2007 May;151(2):278-84
references.pmid: 17351652
references.citation: J Pharmacol Exp Ther. 2003 Jul;306(1):245-52
references.pmid: 12682216
references.citation: Arch Dermatol Res. 1995;287(6):572-80
references.pmid: 7487145
references.citation: Br Med J. 1974 Dec 21;4(5946):693-5
references.pmid: 4441863
references.citation: Cell. 2011 Dec 23;147(7):1615-27
references.pmid: 22196735
references.citation: J Neurosci. 2008 Apr 23;28(17):4331-5
references.pmid: 18434511
references.citation: J Invest Dermatol. 2010 May;130(5):1468-70
references.pmid: 20072136
references.citation: Eur J Pharmacol. 1991 Dec 10;209(1-2):57-61
references.pmid: 1814760
references.citation: Pain. 2012 Sep;153(9):1890-1897
references.pmid: 22770638
references.citation: Nat Neurosci. 2001 Jan;4(1):72-7
references.pmid: 11135647
references.citation: J Clin Invest. 1951 Jan;30(1):37-49
references.pmid: 14803555
references.citation: Eur J Pharmacol. 1995 Mar 14;275(3):229-33
references.pmid: 7539379
references.citation: Vrach Delo. 1971 Apr;7:150-2
references.pmid: 5140117
references.citation: Eur J Pharmacol. 2002 Jul 19;448(2-3):175-83
references.pmid: 12144939
references.citation: Hepatology. 2012 Oct;56(4):1391-400
references.pmid: 22473838