Study of the dose-dependence of the laser of low power, in the regeneration of sciatic nerve of rats after injury for crushing

Abstract

We will verify if the irradiation with low power laser accelerates the morphological and functional recovery of peripheral nerves, in proportion to dose applied, after a crush injury. For this, 72 Wistar rats (weighing approximately 220 g), will be submitted to a crushing injury to the sciatic nerve with a special gripper calibrated with a pre-determined load of 5.000 grams, applied for 10 minutes. The crushed nerves will be submitted to irradiation of laser diode (AsGaAL) low power (100 mW of power, 830 nm wavelengths, and continuous mode). The animals will be divided into six groups; a control group, a injured group without treatment and 4 injured and treated groups, with different doses of laser (35, 70, 140 and 280 J/cm2). The Functional Index Sciatic will be evaluated, starting before surgery and every week after the injury and treatment with the laser. On the 21st postoperative day, the animals will be sacrificed with excessive dose of anesthetic and the muscles, nerves and ganglia will be dissected and analyzed by biomechanical testing and molecular analysis of protein expression (zimografia, immunofluorescence and western blot). Gastrocnemius muscle will be submitted to a mechanical testing of traction, where maximal load and stiffness will be measured. In the protein expressions analysis the tibial anterior muscle will be analyzed by zimografia, and the sciatic nerve and the ganglia of the dorsal root will be analyzed by immunofluorescence and western blot. All data will be submitted to the regression analysis linear, with level of significance set at 5% (p <0,05). (AU)