Low level laser influence in the modulation of inflammation and tissue repair of rat Achilles tendon after partial injury

Abstract

To evaluate the modulation of pro-inflammatory and tissue repair in partially injured Achilles tendons under the action of low level laser (LLL), more specifically investigate the differences in the release of pro-inflammatory interleukin (IL-1²), the enzyme cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in the Achilles tendons of animals treated with LLL and also histological analyze of the organization of collagen fibers and the presence of types I and III collagen of the partially injured Achilles tendons treated with LLL.Materials and Methods: Will be used 50 male Wistar rats (Rattus norvegicus var. Albinus, Rodentia, Mammalia), with 5 weeks of age and body weight of 270-370 grams, which will be anesthetized and partial damage to the Achilles tendon with guillotine without blade which will be released a weight of 186 grams from a height of 20 cm above the Achilles tendon of the animal, corresponding to a potential energy of 364.9 mJ. After this procedure these are allocated into five groups of 10 animals each, with the control group (CG) 10 animals will not suffer the injury and any form of treatment, sham group III (GSII): 10 animals who will suffer the injury and will be subjected to simulated application of LLL for 3 days, the laser group III (GLIII): 10 animals who will suffer the injury and will be submitted to the application of LLL for 3 days, sham group VII (GSVII): 10 animals who will suffer the injury and that will be submitted to the simulation of application of LLL for 7 days and laser group VII (GLVII): 10 animals who will suffer the injury and will be submitted to the application of LLL for 7 days. The equipment will be (near infrared) with GaAlAs semiconductor active medium MMOptics brand, with » 780 nm, beam area of 0.04 cm² and average power of 40 mW, was applied in a point situated at the midpoint on the Achilles tendon injury of animals, starting 24 hours after injury was induced. Irradiation for GLIII and GLVII is in continuous mode with fluence equal to 3.0 J/cm2 for 3 seconds and the final total energy of 0.12 J. In all irradiations will be used the contact technique.The animals will be sacrificed at 4 and 8 days (respectively) and their tendons are surgically removed by dissection from the calcaneal insertion to the myotendinous junction. Immediately the tendons will be washed in 0.9%.Then these samples will be fixed in 10% buffered formalin and after 24 hours will be forwarded to the histological analysis of fiber organization and type of collagen (birefringence) and immunohistochemistry for interleukin-1beta, cyclooxygenase 2 and prostaglandin E2.Once collected, will be held normality for designation of statistical parametric or nonparametric. After this, the data will be analyzed by the Student t test and ANOVA statistical program Graph Pad Instat. The data will be prepared by means, medians, quartiles and standard deviation of the mean. Expected Results: It is expected that application of LLL in the partially injured tendon reduces the release of IL-1² and thus COX-2 and PGE2, and the effect of control and also to prevent degeneration of these tendons. In addition to promoting increased presence of collagen type I and realignment of collagen fibers of tendon injuries. (AU)