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Effect of low intensity laser therapy in an experimental model of cranioencephalic trauma in rats

Abstract:

The aim of this study was to analyze the effects of phototherapy with low intensity laser on the inflammatory reaction after rat brain injury. Cryogenic injury was performed at the brain of 16 male Wistar rats (250-300g) using a cooper probe at -80° C. Immediately, 24 h and 48 h later, the rats received laser irradiation using a GaAlAs laser (830 nm, 100 mW). The samples were randomly divided into four groups (n= 4 per group): A: control (non- irradiated); B: energy density of 3.2 J/cm2; C: 6.4 J/cm2; D: 9.6 J/cm2. Three days later, the cerebral vascular permeability and the inflammatory cells at the trauma site were evaluated. For vascular permeability analysis, 2 h prior sacrifice an intra vascular injection of Evans blue stain was done in the rats. For inflammatory cells counting, frozen samples were sectioned and the histological slides were stained with Giemsa. The data were compared by either ANOVA or KruskallWallis complemented by the Dunn's test. The irradiated groups presented higher cerebral vascular permeability than controls (A: 2.6 ± 0.8; B:12.0 ± 2.0; C: 13.1 ± 4.1, and D: 12.4 ± 1.8; p=0.016). The inflammatory cell numbers of irradiated samples were similar to controls (A: 65 ± 6; B:85 ± 9; C: 84 ± 14, and D: 83 ± 3; p=0.443). The data showed that phototherapy with low intensity laser modulates the inflammatory reaction in the brain by increasing the cerebral vascular permeability after a cryogenic trauma.