The Mechanism Of Alopecia Areata Model Mice Aggravated By Chronic Mild Unpredictable Stress

Purpose: Alopecia areata is a common hair loss disease, its pathogenesis is not fully understood, but studies have shown that the development of alopecia areata disease may involve multiple factors,such as immunity, microcirculation, psychology. The first part of this experiment is the use of synthetic small molecule interferon inducers imiquimod, mouse models of alopecia areata is prepared by using its immune modified role. The second part of the experiment is based on the model of alopecia areata, chronic unpredictable mild stress is added to the alopecia areata model mice, meanwhile vasodilator alprostadil which used to intervene in the impact of chronic unpredictable mild stress is added. The purpose is to explore the effect and molecular mechanisms of unexpected chronic unpredictable mild stress in imiquimod-induced alopecia areata model, to provide new ideas and experimental evidence for psychological interventions in alopecia areata disease.Methods: 1. Imiquimod cream was used to establish C3H/HeJ alopecia areata model,then skin of the model mice was compared with the control group in the changes. 2.All the mice divided randomly into the control group(Control group), imiquimod group(M group), imiquimod + chronic mild unpredictable stress group(MS group), imiquimod + chronic mild unpredictable stress + alprostadil group(MSAL group). The day before the start of the experiment and the day 7,14, 21 was selected to weigh and photograph mice, after the end of the experiment, the behavior change of mice was observed, the skin specimens was collected and the levels of serum adrenocorticotropic hormone(ACTH) in mice was detected. ELISA kit was used to measure the IFN-γ and TNF-α in the skin tissue of mice; Endothelial cell marker CD31 was used to label vessel, and counted microvessel density(MVD); Immunohistochemical method was used to detecte the changes of the expressions of VEGF and BFGF in the skin tissue of mice.Results: 1. For using imiquimod cream smear to establish C3H/HeJ alopecia areata model, the nuchal skin of mice was obviously patchy unhairing, the levels of IFN-γ and TNF-α in skin tissue increased, lesion characteristics was similar to alopecia areata of human, the model can be successfully induced alopecia areata.2.(1)Compared with Control group and M group, the weights of mice in MS group and MSAL group were significantly reduced(P<0.05),the moving distances and the number of grooming behavior in 3mins of Open-field test of mice in MS group and MSAL group were significantly reduced(P<0.05), the central cell residence time of mice in MS group and MSAL group were significantly were significantly decreased(P<0.05), the contents of serum ACTH in mice of the MS group and MSAL group were significantly higher than those of M group(P<0.05),which suggested that chronic mild unpredictable stresssuccessfully modeled the stress response of the mice.(2) At the end of the experiment, compared with Control group, the mice in M group, MS group and MSAL group occurred in varying degrees of hair loss,the severity of MS group was similar with MSAL group, M group was lighter.A lot of inflammatory cells aggregated in the skin tissue of M group, MS group and MSAL group,just little in Control group.(3) Compared with Control group,the contents of IFN-γ and TNF-α of mice skin tissue in M group, MS group and MSAL group were significantly increased(P <0.05), the contents of IFN-γ and TNF-α of mice skin tissue in MS group and MSAL group were significantly higher(P <0.05).(4) Compared with Control group, the vascular density of mice skin tissue in M group, MS group and MSAL group were significantly reduced(P <0.05), compared with M group, the vascular density of mice skin tissue in MS group and MSAL group were significantly reduced(P <0.05), compared with MS group, the vascular density of mice skin tissue in MSAL group were significantly increased(P <0.05).(5) Compared with Control group, the immunohistochemical staining scores of VEGF and BFGF of mice skin tissue in M group, MS group and MSAL group were significantly reduced(P<0.05), compared with M group, the immunohistochemical staining scores of VEGF and BFGF of mice skin tissue in MS group and MSAL group were significantly reduced( P<0.05), compared with MSS group, the immunohistochemical staining scores of VEGF and BFGF of mice skin tissue in MSAL group were significantly increased(P<0.05).Conclusion: 1. External use of imiquimod can cause hair loss, which successfully established mouse model of alopecia areata.2. Chronic mild unpredictable stress can simulate the body’s stress response well.3. Chronic mild unpredictable stress aggravated hair loss in alopecia areata model mice, promoted further immune disorders in mouse skin tissue.4. Chronic mild unpredictable stress lead to microcirculation disturbance in mice, resulting in that the vascular density of skin tissue was reduced, angiogenesis relevant factor VEGF and BFGF was decreased. 5. Alprostadil can partially reverse the effects of chronic mild unpredictable stress in mouse skin microcirculation, but no significant improvement in the phenomenon of hair loss in mice.