【Animal modeling】-Protective effects of different sunscreen standards on UV-induced skin photodamage in rats

  Objective To study the protective effect of different sunscreen standard products on UV-induced skin photodamage in rats, and to provide background data for the evaluation of sunscreen efficacy of sunscreen cosmetics.

  Methods Using long-wave ultraviolet (UVA, 320~400nm, 4.5mJ·cm-2·s-1) + medium-wave ultraviolet (UVB, 280~320nm, 0.036mJ·cm-2·s-1) radiation method to establish skin light Toxic injury rat models were irradiated twice a week for 4 consecutive weeks, with a cumulative radiation time of 440 min. Each sunscreen standard group (S1, S2, P2, P3, P7) applied sunscreen standard 30 minutes before each exposure. After the experiment, the skin was histopathologically observed, and the expression of skin melanoma-specific marker (HMB45) was detected by immunohistochemistry.

  Results Compared with the model group, the four indexes of epidermal thickening, sebaceous hyperplasia, skin damage score and melanoma-specific marker (HMB45) expression in the S2 group were significantly reduced (P<0.05); Compared with the model group, the three indexes of injury score and HMB45 expression were significantly reduced; the SI group [protection against UVA (PFA) 4.5] was significantly reduced in the two indexes of epidermal thickening and skin injury score compared with the model group; One index of epidermal thickening was significantly reduced compared with the model group. In general, the protective effect of the standard product is in line with the PFA and sun protection factor (SPF) values.

  Conclusion The protective effect of sunscreen cosmetics on skin photodamage caused by ultraviolet rays is related to PFA and SPF values. This research method can be used to evaluate the sunscreen efficacy of sunscreen cosmetics.