Mechanism Of Stress Affect On The Synthesis Of Melanin In The Depigmentation Mice Model

Purpose: 1 .Establishment and comparison of two models of depigmentation in animals to select the best one for further studies. 2. Discussion of the role of the nervous, the immune and the endocrine models of stress on mouse skin depigmentation and synthesis of melanin, to provide more reliable experimental data of skin depigmentation, the disease prevention and treatment and also drug development.Methods: 1. Hydrogen peroxide and hydroquinone were used to establish two depigmentation models in animals which were then compared. 2. We randomly divided the C57BL/6J male mice into 5 groups, the control group (Ctrl group), the Hydroquinone group (HQ group), the Hydroquinone + Restraint stress group (HQ + GC group), the Hydroquinone + interferon group (HQ + IFN group) and the Hydroquinone + Hydrocortisone group (HQ + GC group). Using the hydroquinone bleaching method, we imposed restraint stress to mice of the HQ + RS group, injectedα-2a recombinant human interferon to the HQ + IFN group and injected Hydrocortisone to the HQ + GC group. After the end of the test, we fixed the hippocampus conventionally, and we made the H&E staining slices to observe the structural changes in the CA3 region. We also fixed the skin structure conventionally and made the H&E staining slices. The organizational structure of the mice's skin and the number of hair follicles were observed under the microscope. We weighed the thymus and the spleen of the mice and computed the index value of these two structures. We used ELISA kit to measure the content of the serum immunoglobulin G (IgG), immunoglobulin M (IgM) and the serum adrenocorticotropic hormone (ACTH).Results: 1. For the Hydrogen peroxide model, the skin of the mice had a serious damage, however the growth of the hair was not significantly restrained. While for the Hydroquinone model, there was no megascopic damage but the growth of the hair follicles was restrained significantly. This result may indicate that Hydroquinone is better for establishing the bleaching model. 2. (1)The weights of mice and the assessment of open field behavior in the HQ + RS group, HQ + IFN group and the HQ + GC group were all lower than those in the Ctrl group and the HQ group, which suggested that restraint stress,α-2a recombinant human interferon and Hydrocortisone successfully modeled the stress response of the mice. (2) Compared with the Ctrl and HQ groups, the CA3 hippocampus regions of mice of the groups HQ + RS, HQ + IFN and HQ + GC, had irregular arrangements, and the number of nerve cells was reduced with apparent structural changes. (3) The contents of IgG in mice from HQ, HQ + RS and HQ + IFN groups were markedly higher than that of the Ctrl group (P<0.05), while the IgG amount in the HQ + GC group was significantly lower than that of the Ctrl group. Further, the contents of IgM in mice of HQ, HQ + RS, HQ + IFN and HQ + GC groups were markedly higher than that of the Ctrl group(P<0.05). The index values of mice thymus of HQ + RS ,HQ + IFN and HQ + GC groups were lower than those of HQ and Ctrl group(P<0.05). The index values of mice spleen of HQ + RS and HQ + GC groups were lower than those of HQ and Ctrl group. The index values of mice spleen of HQ + IFN group were higher than those of HQ and Ctrl group(P<0.05). (4) The contents of serum ACTH in mice of the groups HQ + RS, HQ + IFN and HQ + GC were all significantly higher than those of Ctrl and HQ groups(P<0.05). (5) Compared with the Ctrl group, both the total number of skin hair follicles and the number of hair follicles in growth period, of the mice of HQ, HQ + RS, HQ + IFN and HQ + GC groups reduced significantly. Compared with the HQ group(P<0.05, the total number of skin hair follicles of mice of HQ, HQ + RS, HQ + IFN and HQ + GC groups reduced in differently.Conclusion: 1. Hydrogen peroxide can restrain the melanin synthesis more effectively, thus this model of depigmentation was selected. 2. Restraint stress,α-2a IFN injection and hydrocortisone injection, can imitate the stress response perfectly. 3. Restraint stress affected the melanin synthesis through the change of three systems: the nervous, the immune and the endocrine system. 4. The injection ofα-2a IFN increased the immune factors, which caused the change of both the nervous and the immune system, and thus the melanin synthesis in the skin was affected. 5. The injection of hydrocortisone increased the glucocorticoides inside the organism; hydrocortisone could obviously affect the production of the skin melanin and this affection was made through the change of both the nervous and the immune systems of the organism.