Abstract: 【Abstract】 Objective To observe and analyze depression-like behavioral performances of mouse models of vitiligo. Methods Fifteen female C57BL/6 mice aged about 9 weeks were modeled for vitiligo. Whether the mouse models of vitiligo were successfully constructed or not was determined by macroscopy and full-thickness epidermal immunofluorescence staining of mouse tail tissues on day 23 after the start of the experiment; on day 8 （pre-modeling stage） and day 21 （early modeling stage）, the elevated plus maze test and the open field test were used to evaluate the behavioral performances of the mice, including the number of entry into the open arms, percentages of time spent in the open arms, percentages of time spent in the central area and total distance traveled, aiming to assess whether depression-like behaviors were exhibited in the mouse models of vitiligo. To further clarify the degree of the impact of vitiligo modeling on the depression-like state in mice, 20 female C57BL/6 mice were equally divided into 2 groups: vitiligo modeling group and vitiligo modeling + chronic restraint stress group; the mice in the vitiligo modeling + chronic restraint stress group were subjected to chronic restraint stress on day 9, that is, these mice were placed in centrifuge tubes and restrained for about 6 hours every day for 28 consecutive days; on days 7, 22, 29 and 38 after the start of vitiligo modeling, the above-mentioned behavioral indicators were determined by the elevated plus maze test and open field test in the 2 groups. Repeated measurement data in a single group were compared before and after treatment by using paired t-test, and repeated measurement data at multiple time points were compared by using two-way repeated measures analysis of variance. Results By macroscopy, the mice gradually developed well-defined white patches on the tail skin during vitiligo modeling, which were similar to the clinical manifestations of vitiligo patients; on day 23, full-thickness epidermal immunofluorescence staining of the mouse tail tissues was conducted and showed obvious infiltration of CD8+ T cells and a decrease in the number of Melan-A-positive epidermal melanocytes under a laser confocal microscope, which were consistent with typical pathological characteristics of vitiligo; based on the macroscopic results and immunofluorescence findings, a total of 12 mouse models of vitiligo were successfully constructed on day 23. The elevated plus maze test showed that the number of entry into the open arms and the percentages of time spent in the open arms were significantly lower in the 12 mouse models of vitiligo on day 21 （2.33 ± 1.78 times, 5.01% ± 5.27%, respectively） than in those on day 8 （10.75 ± 2.30 times, 29.20% ± 12.48%, t = 9.63, 6.36, respectively, both P < 0.001）; the open field test showed that the percentages of time spent in the central area and total distance traveled were also significantly lower in the mouse models on day 21 （2.31% ± 1.53%, 2 518.31 ± 528.38 cm, respectively） than in those on day 8 （4.47% ± 2.65%, 3 533.45 ± 465.47 cm, t = 2.40, 5.47, P = 0.036, < 0.001, respectively）. In the chronic restraint stress test, a total of 14 mouse models of vitiligo were successfully constructed on day 23, including 5 in the vitiligo modeling group and 9 in the vitiligo modeling + chronic restraint stress group. There were no significant differences in the number of entry into the open arms, percentages of time spent in the open arms, percentages of time spent in the central area, and total distance traveled between the vitiligo modeling group and the vitiligo modeling + chronic restraint stress group on days 7, 22, 29, and 38 （F = 0.21, 0.20, 0.46, 2.35, P = 0.889, 0.893, 0.719, 0.134, respectively）; moreover, all the above indicators significantly changed over time （all P < 0.001）, except for the total distance traveled （P = 0.422）. Conclusion The mouse models of vitiligo developed depression-like behavior at the early modeling stage, and the degree of depression could not be further deepened by chronic restraint stress on the basis of vitiligo modeling.

Key words: Vitiligo, Disease models, animal, Depression, Behavioral manifestations, Chronic restraint stress, Elevated plus maze test, Open field test