RESUMO
Objective: To determine the efficacy of D980-nm laser in dissolving fat and renewing skin, and to explore the clinical application of D980-nm laser in reconstruction of photodamaged skin. Methods: Eighteen 12-14 month-old male Sprague-Dawley rats, weighing 400-450 g, were randomly divided into 3 groups ( n=6). The rat skin at the left side was exposed to D980-nm laser irradiation at a density of 20 J/cm 2, a power of 8 W, a pulse width of 20 ms, and a pulse frequency of 40 Hz for 1 time (group A), 2 times of 5-minute interval (group B), and 3 times of 5-minute interval (group C) as a treatment course, for 4 treatment courses with an interval of 1 week; the other side of the skin was not treated as the control groups (groups A1, B1, and C1, respectively). After 8 weeks, the skin was harvested for HE staining and immunohistochemical staining to observe the structure changes of skin, to measure the dermal thickness, to count the number of fibroblasts, and detect the expressions of transforming growth factor ß 1 (TGF-ß 1) and basic fibroblast growth factor (bFGF). Results: Compared with groups A1, B1, and C1, the skin structure was significantly improved in groups A, B, and C. After D980-nm laser irradiation, the number of fat cells decreased; local angiogenesis was observed; the total number of fibroblasts and fibers increased; the collagen fiber had large diameter, and arranged closely and regularly; the dermal thickness and the number of the fibroblasts increased; and the expressions of TGF-ß 1 and bFGF were significantly enhanced, showing significant differences ( P<0.05). With increased D980-nm laser irradiation times, the above indexes increased, showing significant differences between group C and groups A, B ( P<0.05). Conclusion: D980-nm laser treatment has lipolytic and tender effect on the skin, and the frequency of the treatment is an important factor in skin renewal.
