title: Cytokine mRNA expression is decreased in the subplantar muscle of rat paw subjected to carrageenan-induced inflammation after low-level laser therapy.
abstract: OBJECTIVE
  The objective of this work was to investigate the anti-inflammatory effects of low-level laser therapy, applied at different wavelengths (660 and 684 nm), on cytokine mRNA expression after carrageenan-induced acute inflammation in rat paw.
  
  
  BACKGROUND
  Low-level laser therapy (LLLT) has been observed to reduce pain in inflammatory disorders. However, little is known about the mechanisms behind this effect or whether it is wavelength-specific.
  
  
  METHODS
  The test sample consisted of 32 rats divided into four groups: A(1) (control-saline), A(2) (carrageenan-only), A(3) (carrageenan + 660 nm laser therapy), and A(4) (carrageenan + 684 nm laser therapy). The animals from groups A(3) and A(4) were irradiated 1 h after induction of inflammation by carrageenan injection. Continuous-wave red lasers with wavelengths of 660 and 684 nm and dose of 7.5 J/cm(2) were used.
  
  
  RESULTS
  Both the 660 nm and 684 nm laser groups had 30%-40% lower mRNA expression for cytokines TNF-alpha, IL-1beta, and IL-6 in the paw muscle tissue than the carrageenan-only control group. Cytokine measurements were made 3 h after laser irradiation of the paw muscle, and all cytokine differences between the carrageenan-only control group and the LLLT groups were statistically significant (p < 0.001).
  
  
  CONCLUSIONS
  LLLT at the 660-nm and 684-nm wavelengths administered to inflamed rat paw tissue at a dose of 7.5 J/cm(2) reduce cytokine mRNA expression levels within 3 h in the laser-irradiated tissue.
authors.affiliation: Instituto de Pesquisa and Desenvolvimento (IP&D), Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, SP, Brazil.
authors.forename: Regiane
authors.initials: R
authors.lastname: Albertini
authors.forename: Antonio Balbin
authors.initials: AB
authors.lastname: Villaverde
authors.forename: Flavio
authors.initials: F
authors.lastname: Aimbire
authors.forename: Jan
authors.initials: J
authors.lastname: Bjordal
authors.forename: Aldo
authors.initials: A
authors.lastname: Brugnera
authors.forename: Josane
authors.initials: J
authors.lastname: Mittmann
authors.forename: Jose Antonio
authors.initials: JA
authors.lastname: Silva
authors.forename: Maricilia
authors.initials: M
authors.lastname: Costa
mesh_terms: D000818:Animals; D002351:Carrageenan; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004487:Edema / Q000209:etiology / Q000378:metabolism* / Q000517:prevention & control; D006614:Hindlimb; D018836:Inflammation Mediators / Q000378:metabolism*; D028022:Low-Level Light Therapy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D012333:RNA, Messenger; D002351:Carrageenan