title: The spinal inhibition of N-type voltage-gated calcium channels selectively prevents scratching behavior in mice.
abstract: The present study investigated the effects of pharmacological spinal inhibition of voltage-gated calcium channels (VGCC) in mouse pruritus. The epidural administration of P/Q-type MVIIC or PhTx3.3, L-type verapamil, T-type NNC 55-0396 or R-type SNX-482 VGCC blockers failed to alter the scratching behavior caused by the proteinase-activated receptor 2 (PAR-2) activator trypsin, injected into the mouse nape skin. Otherwise, trypsin-elicited pruritus was markedly reduced by the spinal administration of preferential N-type VGCC inhibitors MVIIA and Phα1β. Time-course experiments revealed that Conus magus-derived toxin MVIIA displayed significant effects when dosed from 1h to 4h before trypsin, while the anti-pruritic effects of Phα1β from Phoneutria nigriventer remained significant for up to 12h. In addition to reducing trypsin-evoked itching, MVIIA or Phα1β also prevented the itching elicited by intradermal (i.d.) injection of SLIGRL-NH2, compound 48/80 or chloroquine, although they did not affect H2O2-induced scratching behavior. Furthermore, the co-administration of MVIIA or Phα1β markedly inhibited the pruritus caused by the spinal injection of gastrin-releasing peptide (GRP), but not morphine. Notably, the epidural administration of MVIIA or Phα1β greatly prevented the chronic pruritus allied to dry skin model. However, either tested toxin failed to alter the edema formation or neutrophil influx caused by trypsin, whereas they significantly reduced the c-Fos activation in laminas I, II and III of the spinal cord. Our data bring novel evidence on itching transmission mechanisms, pointing out the therapeutic relevance of N-type VGCC inhibitors to control refractory pruritus.
authors.affiliation: Postgraduate Program in Medicine and Health Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Institute of Toxicology and Pharmacology, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: I S
authors.initials: IS
authors.lastname: Maciel
authors.affiliation: Institute of Toxicology and Pharmacology, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Faculty of Pharmacy, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: V M
authors.initials: VM
authors.lastname: Azevedo
authors.affiliation: Postgraduate Program in Medicine and Health Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Laboratory of Genomics and Molecular Biology, Faculty of Biosciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: T C
authors.initials: TC
authors.lastname: Pereira
authors.affiliation: Postgraduate Program in Medicine and Health Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Laboratory of Genomics and Molecular Biology, Faculty of Biosciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Postgraduate Program in Cellular and Molecular Biology, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Bogo
authors.affiliation: Laboratory of Neuroscience, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: A H
authors.initials: AH
authors.lastname: Souza
authors.affiliation: Laboratory of Neuroscience, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: M V
authors.initials: MV
authors.lastname: Gomez
authors.affiliation: Postgraduate Program in Medicine and Health Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Institute of Toxicology and Pharmacology, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Faculty of Dentistry, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: camposmmartha@yahoo.com.
authors.forename: M M
authors.initials: MM
authors.lastname: Campos
mesh_terms: D000208:Acute Disease; D000818:Animals; D000982:Antipruritics / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020864:Calcium Channels, N-Type / Q000378:metabolism*; D002908:Chronic Disease; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011537:Pruritus / Q000188:drug therapy* / Q000503:physiopathology; D012867:Skin / Q000276:immunology; D013111:Spider Venoms / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects* / Q000503:physiopathology; D013997:Time Factors; D014357:Trypsin
chemical_list: D000982:Antipruritics; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; C583821:Phalpha1beta toxin, Phoneutria nigriventer; D016760:Proto-Oncogene Proteins c-fos; D013111:Spider Venoms; D014357:Trypsin
keywords: N-type voltage-gated calcium channels; PAR-2; mice; scratching behavior; trypsin