Photobiomodulation therapy in the modulation of inflammatory mediators and bradykinin receptors in an experimental model of acute osteoarthritis.

The objective of this study was to evaluate the effects of photobiomodulation therapy (PBMT) on inflammatory indicators, i.e., inflammatory mediators (TNF-α and CINC-1), and pain characterized by hyperalgesia and B1 and B2 receptor activation at 6, 24, and 48 h after papain-induced osteoarthritis (OA) in rats. Fifty-four rats were subjected to hyperalgesia evaluations and then divided randomly into three groups-a control group and two groups OA and OA PBMT group by using laser parameters at wavelength (808 nm), output power (50 mW), energy per point (4 Joules), power density (1.78 W/cm2), laser beam (0.028 cm2), and energy density (144 J/cm2)-the induction of osteoarthritis was then performed with 20-µl injections of a 4 % papain solution dissolved in 10 µl of saline solution, to which 10 µl of cysteine solution (0.03 M). The statistical analysis was performed using two-way ANOVA with Bonferroni's post hoc test for comparisons between the 6, 24, and 48 h and team points within each group, and between the control, injury, and PBMT groups, and p < 0.05 was considered to indicate a significant difference. The hyperalgesia was evaluated at 6, 24, and 48 h after the injury. PBMT at a wavelength of 808 nm and doses of 4 J, administered afterward, promotes increase at the threshold of pressure stimulus at 6, 24, and 48 h after application and promote cytokine attenuation levels (TNF and CINC-1) and bradykinin receptor (B1 and B2) along the experimental period. We conclude that photobiomodulation therapy was able to promote the reduction of proinflammatory cytokines such as TNF-α and CINC-1, to reduce the gene and protein expression of the bradykinin receptor (B1 and B2), as well as increasing the stimulus response threshold of pressure in an experimental model of acute osteoarthritis.

Analysis of the effect of phototherapy in model with traumatic Achilles tendon injury in rats.

The aim of this study was to investigate the effect of low-intensity laser (LILT) infrared (830 nm) therapy in tendon inflammation, tendinitis induced by mechanical trauma in rat Achilles tendon. For this, we used 65 young male Wistar rats, weighing ± 300 g divided into different groups: C = control (n = 5) and experimental (n = 10/group), with two different times of sacrifice such as treated with L = laser, D = treated with diclofenac, and T = untreated injured. The tendon inflammation was induced by controlled contusion in the medial region of the Achilles tendon of the animals. The treated groups received some kind of intervention every 24 h, all groups were sacrificed on the 7th or 14th day after the trauma. The tendons were dissected, extracted, and sent for analysis. Histological analysis of the L group showed a decrease in the number of inflammatory cells in relation to other groups in both periods studied. The comparative results between the number of inflammatory cells in the control and treated groups at 7 and 14 days showed statistically significant differences. Qualitative analysis findings obtained by the picrosirius red technique under polarized light showed that in 7 days, the T group presented collagen types I and III in the same proportion; group D presented a predominance of type III fibers, while in group L, type I collagen predominated. The 14-day group D showed collagen types I and III in the same proportion, while in group L, there was a predominance of type I fibers. Biomechanical analysis showed that 7-day groups L and C showed similar stiffness and increased breaking strength. The 14-day groups L and C showed greater rupturing strength as well as increased stiffness angle. Group D showed a decrease of maximum traction strength and degree of rigidity. It was concluded that treatment with LIL in the parameters used and the times studied reduces migration of inflammatory cells and improves the quality of repair while reducing the functional limitations.