Background and aim: Low-power lasers relief pain in some musculoskeletal disorders and accelerate wound healing process. However, there are few reports on effects of low-power lasers on mast cells. In this study the effects of low-power gallium aluminium arsenide laser (Ga.Al.As.laser) radiation on number and degranulation of mast cells of open skin wound bed of rats were studied using quantitative histological methods.
Materials and Methods: Forty-six male rats were randomly divided into experimental and control groups. Each group divided into 3 subgroups based on duration of study: 4 , 7 and 15 days. Under general anesthesia and sterile conditions one circular full thickness skin wound was made on the doesum of neck of each rat. The wounding day was considered as the day zero. From the day one, experimental rats received Ga. Al. Ar. laser radiation at a energy density of 1.2 J/cm2. After doing daily treatments, on days 4, 7 and 15, rats were killed by ether and samples were obtained from wound bed and normal adjacent skin from each rat. Samples were fixed in formalin saline and were prepared for routine histological study. Sections were stained by 0.1% watery solution of toluidine blue and total number of mast cells and their grades (one, two and three) were counted. In grade one, mast cell is intact, in grade two some granules have been extruded from the cell and in the mast cells of grade 3, degranultion is more extensive and widespread. Data were analysed by Student t test.
Results: On the day 4, total number and grade one mast cells were significantly higher in the control group (P<0.01). On days 7 and 15, total number of mast cells and their grades were higher in the experimental group. The grade 2 mast cells on day 7 and grade 1 mast cells on day 15 of experimental group was significantly higher than control group (P<0.05).
Conclusion: Low-power gallium aluminium arsenide laser irradiation on open skin wound of rats reduced significantly total number of mast cells and intact ones at inflammatory phase, and 90 significantly increased active mast cells at proliferation, and intact ones at remodeling phases of the wound healing process.