Zymographic and ultrastructural evaluations after low-level laser irradiation on masseter muscle of HRS/J strain mice.
Low-level laser therapy (LLLT) has been widely used in the treatment of the stomatognathic system dysfunction; however, its biological effect remains poorly understood. This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm(2), 40 mW) on masseter muscle of HRS/J mice after different numbers of laser irradiations (three, six, and ten) for 20 s in alternate days. Three experimental groups were defined according to the number of laser irradiations and three control groups (n=5) were used. On the third day after the last irradiation, all animals were killed and the masseter muscle was removed and processed for the following analysis: (a) transmission electron microscopy, (b) zymography, (c) immunohistochemistry for vascular endothelial growth factor (VEGF) and VEGFR-2. The results showed: (a) with six laser applications, a dilation of T tubules, and sarcoplasmic reticulum cistern, increased pinocytosed vesicles in the endothelium; with ten laser applications, few pinocytic vesicles in the endothelium and condensed mitochondria. (b) Under the conditions of this study, the synthesis of other matrix metalloproteinases was not observed, only the MMP-2 and -9. (c) After ten laser irradiations, immunostaining was observed only for VEGFR-2. We conclude that after six laser applications, ultrastructural changes may facilitate the Ca(+2) transfer to cytosol and increase the fluid transport from one surface to another. The ultrastructural changes and no immunostaining for VEGF with ten applications may decrease the metabolic activity as well as damage the angiogenic process, suggesting that an effective number of laser applications may be less than ten, associating to this therapy a better cost-benefit.
Department of Morphology, Stomatology and Physiology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Avenida do Café, s/n-Monte Alegre, 14040-904, Ribeirão Preto, SP, Brazil. mamieiyo@forp.usp.br
Mamie Mizusaki
MM
Iyomasa
Elen Camargo
EC
Rizzi
Juliane Caroline
JC
Leão
João Paulo Mardegan
JP
Issa
Fernando José
FJ
Dias
Yamba Carla Lara
YC
Pereira
Maria José Vieira
MJ
Fonseca
Fabiana Testa Moura de Carvalho
FT
Vicentini
Ii-Sei
IS
Watanabe
D000818:Animals; D006801:Humans; D028022:Low-Level Light Therapy; D008297:Male; D008406:Masseter Muscle / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008812:Mice, Hairless; D046529:Microscopy, Electron, Transmission; D023421:Models, Animal; D013705:Temporomandibular Joint Disorders / Q000532:radiotherapy; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse