title: Infrared (810-nm) low-level laser therapy on rat experimental knee inflammation.
abstract: Arthritis of the knee is the most common type of joint inflammatory disorder and it is associated with pain and inflammation of the joint capsule. Few studies address the effects of the 810-nm laser in such conditions. Here we investigated the effects of low-level laser therapy (LLLT; infrared, 810-nm) in experimentally induced rat knee inflammation. Thirty male Wistar rats (230-250 g) were anesthetized and injected with carrageenan by an intra-articular route. After 6 and 12 h, all animals were killed by CO(2) inhalation and the articular cavity was washed for cellular and biochemical analysis. Articular tissue was carefully removed for real-time PCR analysis in order to evaluate COX-1 and COX-2 expression. LLLT was able to significantly inhibit the total number of leukocytes, as well as the myeloperoxidase activity with 1, 3, and 6 J (Joules) of energy. This result was corroborated by cell counting showing the reduction of polymorphonuclear cells at the inflammatory site. Vascular extravasation was significantly inhibited at the higher dose of energy of 10 J. Both COX-1 and 2 gene expression were significantly enhanced by laser irradiation while PGE(2) production was inhibited. Low-level laser therapy operating at 810 nm markedly reduced inflammatory signs of inflammation but increased COX-1 and 2 gene expression. Further studies are necessary to investigate the possible production of antiinflammatory mediators by COX enzymes induced by laser irradiation in knee inflammation.
authors.affiliation: Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Rodney Capp
authors.initials: RC
authors.lastname: Pallotta
authors.forename: Jan Magnus
authors.initials: JM
authors.lastname: Bjordal
authors.forename: Lúcio
authors.initials: L
authors.lastname: Frigo
authors.forename: Ernesto Cesar Pinto
authors.initials: EC
authors.lastname: Leal Junior
authors.forename: Simone
authors.initials: S
authors.lastname: Teixeira
authors.forename: Rodrigo Labat
authors.initials: RL
authors.lastname: Marcos
authors.forename: Luciano
authors.initials: L
authors.lastname: Ramos
authors.forename: Felipe de Moura
authors.initials: Fde M
authors.lastname: Messias
authors.forename: Rodrigo Alvaro Brandão
authors.initials: RA
authors.lastname: Lopes-Martins
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D002351:Carrageenan / Q000633:toxicity; D051545:Cyclooxygenase 1 / Q000235:genetics; D051546:Cyclooxygenase 2 / Q000235:genetics; D015232:Dinoprostone / Q000378:metabolism; D005070:Evans Blue; D005119:Extravasation of Diagnostic and Therapeutic Materials; D005786:Gene Expression Regulation; D007375:Interleukin-1 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D007719:Knee Joint / Q000378:metabolism / Q000528:radiation effects; D007958:Leukocyte Count; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D008565:Membrane Proteins; D005070:Evans Blue; D002351:Carrageenan; D009195:Peroxidase; C077623:Ptgs2 protein, mouse; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496512:Ptgs1 protein, mouse; D015232:Dinoprostone