Organization of collagen in skin repair of diabetic mice when treated with low-power laser: comparison of energy densities

Abstract

Cutaneous ulcers are a public health problem in Brazil and the world and the initiative of the implementation of Low Power Laser Therapy in these ulcers, including those from diabetic patients, has shown positive results, but there are few studies about it and, consequently, there is much to investigate to establish optimized protocols. The objective of this study is to evaluate the ordering of collagen by polarization microscopy during the repair of ulcers of diabetic animals subjected to two regimes of power delivery: single and fractionated. Will be used 36 male Wistar rats (Rattus norvegicus Albinus) with diabetes induced by intraperitoneal injection of streptozotocin (50 mg/kg). There will be three groups: (1) control group (CG) - the dorsal ulcer will not be subjected to treatment, (2) single energy density (GU) - dorsal ulcer will be treated with laser therapy two hours after the wound, (3) fractional energy density (GF) - dorsal ulcer will receive laser therapy four times. The ulcer will be made with a punch of 8 mm on the back of the animal after shaving. The application of laser parameters are: » = (660 ± 2) nm, I = 6mW/cm2, D = 1 J/cm2 and t = 167 s in group GF, and D = 4 J/cm2 and t = 668 s in the group GU. At the end of 0, 3, 7, and 14 days after the creation of lesions will be done euthanasia and the ulcers removed for analysis under a microscope of polarization and the ordinary optical microscope. The following parameters will be assessed: the presence and type of inflammatory infiltrate, the presence of granulation tissue, and the birefringence of collagen type I. The data will be evaluated for normality and subjected to appropriate statistical analysis.(AU)