APPAEENT RADIATION PROTECTION AGAINST LOCAL 

 AGEING EFFECTS IN THE SKIN OF MICE 



HERMAN B. CHASE 



Brown University, Rhode Island, U.S.A. 



In connection with comments made on ageing at this conference, I would 

 like to mention first a few results which seemed peculiar at the time and then 

 give the explanation. A peculiar phenomenon was observed in that in order to 

 protect against local ageing effects, one protection was radiation itself, a 

 rather anomalous situation, to say the least. 



The experimental set-up, obviously for different reasons at the beginning, 

 was to use the two sides of an animal, one side irradiated, the other as the 

 control, a standard technique. On the irradiated side the hair greying effect 

 occurs and this was the primary interest at the time. Our study was then 

 extended to observe the other effects of irradiation, the other effects on the 

 grey side as compared with the control side. The first results were peculiar in 

 that for the characteristics being studied, the skin appeared younger on the 

 grey side than on the control side. 



Six different traits or effects were examined. One was the irregular 

 patches of keratosis which occur after irradiation and with ageing. This 

 characteristic was less pronounced on the irradiated side than on the control 

 side, but it had first increased then decreased. Another trait was excessive 

 epidermal pigmentation. Mice normally do not have much pigment in the 

 epidermis, but potential pigment cells are there and they flare up at times, 

 especially after irradiation and also with ageing. On the X-rayed side there 

 was first a little increase then a decrease to a level where no pigment appeared. 

 Over the same period, however, epidermal pigmentation on the control side 

 continued to increase slowly. Even the density of hair showed the same 

 difference, the density on the control side decreasing with age, the density on 

 the irradiated side remaining comparatively high. Wound healing was not 

 as clear a trait, but the irradiated side was not at a disadvantage, except for 

 a period immediately after irradiation. The collagen study is not as complete, 

 but again the irradiated side appeared at least as "youthful" as the control 

 side, possibly more so. The sixth trait is of course the greying itself. There is 

 some increase in the number of grey hairs with time on the irradiated side, 

 but also a considerable average increase on the control side. 



What did all this mean? The radiations varied from 200 to 1,000 r, the 

 1,000 r giving the maximum greying effect. A major part of the explanation 



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