P-06   INTERMITTENT FOOT SHOCK STRESS PROLONGS TELOGEN STAGE IN THE THIRD POSTNATAL HAIR CYCLE OF MICE

M. Katayama*, E. Aoki*, Z. Chao*, H. Suzuki**, T. Shibasaki***, S. Kawana* *Department of Dermatology, **Department of Pharmacology, ***Department of Physiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.

Background: Recent evidences indicate that stress influences skin diseases and cutaneous functions. Recently we noted that intermittent foot shock stress prolongs the telogen stage in the second hair cycle after depilation. Objective: The aim of this study is to evaluate the efficiency of the same stress in the third postnatal hair cycle of mice. Methods: Female C57BL/6 mice (11wk old) were used in this study. The stressed group (n=20) was given electrical foot shock with a communication box for 3 to 4 weeks. The control group (n=21) was kept without stress. After this period we observed the hair cycle macroscopically and histologically. And we evaluated the hair cycle stage in H&E stained sections by calculating each hair cycle score. Then we analyzed the data using the Mann-Whitney U-test. Results: Macroscopically, only one mouse had a small anagen island in the tail side on its back in the stressed group. But all of the rest mice were in the telogen stage. On the other hand 17 mice had developed the anagen stage, four of those mice have already changed the catagen stage in the control group. Histologically, the hair cycle scores in the control group were significantly higher than that in the stressed group (p<0.05). Conclusion: We have demonstrated that intermittent foot shock stress prolongs the telogen stage in the spontaneous hair cycle of mice. The responses in the systemic stress condition in the spontaneous hair cycle of mice were similar to it stage in the second hair cycle after depilation.