Histological observation of hairless mice skin after exposure to Simulated Solar Light: Comparison between the histological findings with different methodologies and 3R principle correlations.

<bold>Background: </bold>Albino hairless mouse (AHM) has been used as a biological model in photodermatology. However, the experimental landscape is diverse to follow and need particular attention.<bold>Purpose: </bold>Irradiation parameters were investigated for the development of a protocol to assess alterations in the AHM skin using Simulated Solar Light (SSL). The present study was compared with published articles (last 15 years) according to irradiation protocols, morphological findings to minimize animal suffering and UV exposure.<bold>Materials and Methods: </bold>Three groups: Control (G1), experimental - sunburn (G2) and skin photodamage assay (G3). G2 were immobilized and exposed to SSL once for 15, 30 and 45min. G3 were exposed to SSL, without immobilization, for 15min once a day for one week. The dorsal skin was analyzed using hematoxylin and eosin technique.<bold>Results: </bold>G2 displayed different sunburn degrees. Based on the profile of the observed morphological alterations, a 15min irradiation was chosen as the exposure time to expose G3, without immobilization, for 5 consecutive days.<bold>Conclusion: </bold>These conditions produced the same morphological changes in the AHM with a shorter solar exposure time, without immobilizing the animals but using environmental exposure fluences, conforming to 3R (reduction - refinement - replacement) recommendations. [ABSTRACT FROM AUTHOR]