Effects of low-level laser therapy on liver regeneration and laser parameters employed / Efeitos da laserterapia de baixa potência na regeneração hepática e parâmetros empregados de laser

Low-level laser therapy has several biological effects; one of them is tissue regeneration. Recent studies have been held on the application of laser therapy on the liver of rats after partial hepatectomy to promote liver regeneration. The aim of this article was to review the recent studies on the effects of low-level laser therapy on rat liver regeneration after partial hepatectomy and the laser parameters used in those studies. A review of recent relevant literature was performed in Pubmed, Scielo, Medline, and Bireme databases. Articles related to the application of low-level laser therapy on hepatic regeneration were included. Articles with hepatic regeneration in the presence of pathologies were not included. Nine studies were found matching the study criteria. In most studies, low-level laser therapy promoted liver regeneration after partial hepatectomy, without further damage to the remaining liver. Not all laser parameters required for the reproducibility of the study were described by all authors. The therapeutic use of low-level laser therapy in liver regeneration can be promising; however, since the liver is a vital organ, and the laser application is intraoperative, future studies are necessary. The parameters used must be properly described and standardized to allow the reproducibility of the study, in order to define a therapeutic window and thus, consider its clinical use. It is also essential to clarify the mechanisms by which laser promotes liver regeneration to guarantee its safety and therapeutic efficacy.

Laserterapia de baixa potência tem vários efeitos biológicos, sendo um deles a regeneração de tecido. Sua aplicação no fígado de ratos após hepatectomia parcial para promoção de regeneração hepática tem sido estudada recentemente. O objetivo deste artigo foi revisar os estudos recentes dos efeitos da laserterapia de baixa potência na regeneração de fígado de ratos após hepatectomia parcial de fígado e os parâmetros de laser empregados. Uma revisão da literatura relevante recente foi realizada nas bases de dados Pubmed, Scielo, Medline e Bireme. Artigos sobre a aplicação da laserterapia de baixa potência na regeneração de fígado foram incluídos. Artigos sobre regeneração hepática na presença de patologias foram excluídos. Nove estudos foram encontrados correspondendo aos critérios do estudo. Na maioria dos estudos, a laserterapia de baixa potência promoveu regeneração hepática após hepatectomia parcial, sem causar danos adicionais ao fígado remanescente. Não foram descritos todos os parâmetros necessários para reprodutibilidade dos estudos por todos os autores. O uso terapêutico da laserterapia de baixa potência na regeneração de fígado pode ser promissor, entretanto, como o fígado é um órgão vital e a aplicação do laser é intraoperativa, estudos futuros são necessários, assim como os parâmetros da aplicação de laser precisam ser descritos apropriadamente e padronizados, para permitir a reprodutibilidade do estudo, para que uma janela terapêutica possa ser definida e seu uso clínico possa ser considerado. Também é essencial esclarecer através de quais mecanismos o laser promove regeneração de fígado para garantir sua segurança e eficácia terapêutica.

Low-level Laser Therapy Improves Recovery after Exhausting Exercise induced Fatigue: A Randomized, Double-blind and Placebo Controlled Cross-over Study / 中国运动医学杂志

Objective To explore the effect of low-level laser therapy (LLLT)applied to the quadriceps muscle on the recovery of exhausting-cycling-exercise-induced fatigue.Methods According to a randomised,double-blind and crossover design,16 healthy male students were randomly assigned to an LLLT-1,LLLT-3,LLLT-5 and a placebo group,and received LLLT for 300 s at the dosage of 0.06 J· cm-2,0.18 J·cm-2,0.3 J·cm-2 and 0 to the bilateral rectus femoris after the exhausting-cycling-exercise-induced fatigue.The blood lactate(BL),heart rate(HR),rated perceived exertion(RPE)and visual analogue scale(VAS)were assessed before the exercise,immediately after exercise,10 and 20 min after exercise,as well as immediately after the first Wingate(WG)test,5 and 30 min after the WG test.Meanwhile,the second WG test was performed 40 min after the first WG test.Results The average HR value of LLLT-1 group was significantly lower than the placebo group at 10 min after exercise(P＜ 0.05)and immediately after the WG test(P＜0.01),while that of LLLT-3 and LLLT-5 groups was significantly lower than the placebo group immediately and 5 min after the WG test(P＜0.01).Compared to the placebo group,the average BL of LLLT-1,LLLT-3 and LLLT-5 groups was significantly lower 10 min after exercise(P＜0.05 for all)and that of LLLT-5 group was also significantly lower 30 min after the first WG test(P＜0.05).However,the average blood glucose of LLLT-5 group was significantly higher than the placebo group right after the first WG test(P＜0.05).Moreover,significant increase was observed in the mean(P=0.002)and peak power(P=0.006)at the second WG test and the mean(P=0.048) power at the first WG test of LLLT-3 group,compared to the placebo group.Conclusion LLLT applied to quadriceps muscles after exhausting exercise may enhance recovery,and LLLT at the dose of 0.18 J·cm-2 is of the best effect.