Zymographic and ultrastructural evaluations after low-level laser irradiation on masseter muscle of HRS/J strain mice

Abstract

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.

Laser therapy reduces gelatinolytic activity in the rat trigeminal ganglion during temporomandibular joint inflammation

“…The rats were physically restrained to avoid light beam diffraction. According to a previous study (Iyomasa et al , ), an energy dose of 20 J cm −2 of GaAlAs was used (continuous wave 40 mW, time 20 s, λ = 780 nm, 0.04 cm 2 of spot area), at only one point on the TMJ. The laser irradiation was performed in direct contact with the skin, on one point on the TMJ (Energy: 0.8 J point −1 , power density: 1 W cm −2 ).…”

Ultrastructure and Light Microscope Analysis of Intact Skin after a Varying Number of Low Level Laser Irradiations in Mice

“…The cytoplasmic protrusions of the endothelial cell protruding into the blood vessel lumen suggested angiogenesis. Irradiation with LLL has also shown the proliferation of endothelial cells, contributing to an increase of angiogenesis and acceleration of wound healing in vivo in different tissue types [22–27]. Our data showed that the LLL using an energy density usually recommended for deep structure contributes to nutrients diffusion in all numbers of applications, without revealing damage.…”

GaAs laser therapy reestablishes the morphology of the NMJ and nAChRs after injury due to bupivacaine

“…It is well established that the mitochondrial electron transport chain is photosensitive to red and infrared light, and when activated by LLLT, there is an increase in the space between the inner and outer membranes of the mitochondria, which dilates the mitochondrial crest [74]. Exposure to laser light also increases the synthesis of adenosine triphosphate (ATP) and O 2 consumption [41].…”