| Objective:1.To establish a nude mouse model of acute skin photodamage induced by medium-long wave ultraviolet.2.To explore whether metformin has protective effect on acute photodamage of nude mice induced by medium-long wave ultraviolet.Methods:The acute photodamage model induced by medium-long wave ultraviolet was established by group irradiation of BALB/c Nude mice using a self-made UVA&UVB irradiation device,and the model was evaluated by gross observation and pathological section staining.After stable modeling,the nude mice were randomly divided into blank group,MET group and control group.The blank group does not do any processing,the MET group and control group received 65J/cm~2medium-long wave ultraviolet irradiation,at the same time the MET group was given intraperitoneal injection of MET solution.Then,the skin appearance changes of nude mice were compared by gross observation,the skin pathological changes of nude mice were compared by H&E staining and Masson staining,the ROS of skin tissue were analyzed and compared by flow cytometry,the macrophage infiltration was compared by F4/80immunohistochemical staining,and the expressions of IL-1β,IL-6,TNF-αand MMP-1 were detected by Western blot.Data analysis and mapping were performed using Graph Pad Prism 8.3,and each independent experiment was repeated at least 3 times.Data were expressed as Mean±SD,and t test was used for comparison of data between two groups,One-Way ANOVA test was used for comparison of data between multiple groups,LSD test was used for homogeneous variance and Kruskal-Wallis test was used for heterogeneous variance.When P<0.05,the difference between groups was considered statistically significant.Results:(1)After 65J/cm~2medium-long wave ultraviolet irradiation,the back skin of nude mice in UV group showed more dandruff,skin glossiness decreased significantly,and local redness,swelling,ulceration and scab formation were observed in different degrees.H&E staining showed that the tissue of nude mice in UV group was edema and thickening,the tissue gap was blurred,the skin appendage was reduced or even disappeared,the epidermal was significantly thickened,and the cuticle was hyperkeratosis with parakeratosis.Masson staining indicated that the blue-stained area of UV group was reduced,the distribution was not uniform,the blue-stained collagen was disordered and the continuity was interrupted.The measurement of epidermal thickness under microscope indicated that the epidermal thickness of UV group was significantly higher than that of blank group(P<0.0001).(2)After medium-long wave ultraviolet irradiation at 65J/cm~2and injection,the back skin of nude mice in the MET group showed less lesions,such as dandruff,skin glossiness,local redness,ruptures,and crust-forming.H&E staining showed that compared with the blank group,the MET group and control group showed varying degrees of epidermal thickening,hyperkeratosis with parakeratosis of the cuticle,reduction of skin appendages,and infiltration and expansion of subcutaneous capillaries.The above performance was less severe in the MET group than that in the control group.The epidermal thickness in the MET group was significantly lower than that in the control group(P<0.05).Masson staining showed that compared with the blank group,the blue-stained areas in the MET group and the control group were narrowed to varying degrees,the distribution was uneven,the blue-stained collagen was arranged disorderly,and the continuity was interrupted.The above performance was also less severe in the MET group than in the control group.Flow cytometry showed that ROS in both MET and control groups was significantly higher than that in blank group(P<0.05,P<0.001),but the control group increased more(P<0.01).F4/80immunohistochemical staining showed that the count of macrophages in the MET group and the control group was significantly higher than that in the blank group(P<0.05,P<0.0001),but control group increased more(P<0.05).Western blotshowedthattherelativeexpressionsof IL-1β(P<0.01,P<0.0001),IL-6(P<0.05,P<0.0001),TNF-α(P<0.05,P<0.0001) and MMP-1(P<0.05,P<0.0001)in the MET group and control group were higher than those in the blank group.Compared with control group,the expressionsofIL-1β(P<0.05),IL-6(P<0.05),TNF-α(P<0.05)and MMP-1(P<0.05)in MET group were lower.Conclusion:BALB/c Nude mice irradiated by 65J/cm~2medium-long wave ultraviolet showed acute photodamage on their back skin,which can be used as an animal model of acute photodamage.Metformin may have a certain protective effect on acute skin photodamage by reducing ROS production,reducing IL-1β,IL-6,TNF-α,MMP-1 production,and reducing macrophage infiltration.In this study,the effects of MET on acute skin photodamage were improved and supplemented. |
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