Influência da radiação ultra-violeta-B na cicatrização em pele de ratos

• Autor(a) principal: Korinfsky, Juliana Pedrosa [UNIFESP]
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5034998; http://repositorio.unifesp.br/handle/11600/50360
• topic: Healing; Skin; Solar radiation; Collagen; Cicatrização; Pele; Radiação solar; Colágeno

The integrity of the skin exerts a protective barrier against chemical and physical aggressors. One of the main agents external to its integrity is a direct exposure to sunlight for causing cumulative damage over time. Skin attacks are common event and triggered a series of biochemical events aimed at protection and repair. Exposure of the skin to solar radiation provides several photobiological effects, such as alterations in the shape and function of fibroblasts and the deposition of collagen in the skin. People exposed to intense ultraviolet radiation may have difficulty healing. Objective: To evaluate an influence of RUV-B on the skin healing of rats. Methods: Wistar rats (n = 50) with 3 months of age and weight of 250 g with distributed in 2 groups (experimental and control). No experimental group (n = 40) had a tricotomized back skin exposed to the RUV-B using a 306nm lamp, power 9J / s (W), installed in a wooden box, 15cm away from the animal's back, Seconds, three times a week. At the end of weeks 5, 10, 15 and 20, one exposed to interrupt in each subgroup (n = 10), a skin and photographed and biopsied in a standardized way. The control group was photographed and biopsied without any stimulus. Histopathological study was carried out and as photos were analyzed by 3 dermatologists unrelated to the experiment. As skin lesions were photographed daily up to 45 days later and an area of ​​the lesion was measured by the ImageJ program. It was statistically significant by the coefficient of agreement of Kendal and ANOVA with repetition.Results: Clinically the skin presented from the fifth week, erythematous lesions and over time the lesions become more chronic evolving until keratosis. The histological alterations presented inflammatory lymphomononuclear infiltrate, moderate atypia of basal keratinocytes and infiltration of the superficial dermis. These lesions over time evolved to more intense characteristics and in the twentieth week of exposure, hyperkeratosis and hyperparasqueratosis, atypical basal keratinocytes, epidermal atrophy, inflammatory infiltrate and cytoarchitectural disorganization became evident. There was an increase in the severity of the lesion as the exposure time to UVR increased, both macro- and microscopically. As for the collagen changes in the control group, there was minimal alteration, with total collagen regeneration at 45 days and in the experimental groups there was a reduction from 23% up to 37% and no regeneration at 45 days. The organization of the collagen fibers was less evident in the exposed groups. An inverse proportional relationship between exposure time and percentage of collagen was observed, that is, the longer the exposure time of the skin, the lower the percentage of collagen and, consequently, the longer the healing time of the skin. The control group had the shortest healing time of all the groups exposed, with a mean time of 16.4 days and the RUV20 group had the longest time, among all the exposed groups, 19.4 days. Conclusion: The skin that has been exposed to RUV-B for the longest time has had more severe macroscopic lesions and also more important microscopic changes, both with inflammatory characteristics. These changes may delay the healing process.