title: Acute and persistent nociceptive paw sensitisation in mice: the involvement of distinct signalling pathways.
abstract: OBJECTIVE
  Many fundamental pharmacological studies in pain and inflammation have been performed on rats. However, the pharmacological findings were generally not extended to other species in order to increase their predictive therapeutic value. We studied acute and chronic inflammatory nociceptive sensitisation of mouse hind paws by prostaglandin E(2) (PGE(2)) or dopamine (DA), as previously described in rats. We also investigated the participation of the signalling pathways in acute and persistent sensitisation.
  
  
  METHODS
  Mechanical sensitisation (hypernociception) induced by intraplantar administrations of PGE(2) or DA was evaluated with an electronic pressure meter. The signalling pathways were pharmacologically investigated with the pre-administration of adenylyl cyclase (AC), cAMP-dependent protein kinase (PKA), protein kinase Cepsilon (PKCepsilon), and the extracellular signal-related kinase (ERK) inhibitors.
  
  
  RESULTS
  Single or 14days of successive intraplantar injections of PGE(2) or DA-induced acute and persistent hypernociception (lasting for more than 30days), respectively. The involvement of AC, PKA or PKCepsilon was observed in the acute hypernociception induced by PGE(2), while PKA or PKCepsilon were continuously activated during the period of persistent hypernociception. The acute hypernociception induced by DA involves activation of ERK, PKCepsilon, AC or PKA, while persistent hypernociception implicated ERK activation, but not PKA, PKCepsilon or AC.
  
  
  CONCLUSIONS
  In mice, acute and persistent paw sensitisation involves the different activation of kinases, as previously described for rats. This study opens the possibility of comparing pharmacological approaches in both species to further understand acute and chronic inflammatory sensitisation, and possibly associated genetic manipulations.
authors.affiliation: Faculty of Pharmacy, Federal University of Bahia, Bahia, Brazil.
authors.forename: Cristiane F
authors.initials: CF
authors.lastname: Villarreal
authors.forename: Mani I
authors.initials: MI
authors.lastname: Funez
authors.forename: Florêncio
authors.initials: F
authors.lastname: Figueiredo
authors.forename: Fernando Q
authors.initials: FQ
authors.lastname: Cunha
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Parada
authors.forename: Sérgio H
authors.initials: SH
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D015232:Dinoprostone / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology*; D006614:Hindlimb / Q000187:drug effects* / Q000276:immunology; D007249:Inflammation; D008297:Male; D051379:Mice; D010120:Oxytocics / Q000494:pharmacology*; D010147:Pain Measurement; D010770:Phosphotransferases / Q000378:metabolism; D015398:Signal Transduction; D013566:Sympathomimetics / Q000494:pharmacology*
chemical_list: D010120:Oxytocics; D013566:Sympathomimetics; D010770:Phosphotransferases; D015232:Dinoprostone; D004298:Dopamine