VITAMIN-A STATUS AND METABOLISM OF CUTANEOUS POLYAMINES IN THE HAIRLESS MOUSE AFTER UV IRRADIATION - ACTION OF BETA-CAROTENE AND ASTAXANTHIN

Solar radiations (UVA and B) can cause epidermis photoaging and skin c ancers. These frequently irreversible effects result from the in situ generation of free radicals. However it has been noted that nutritiona l factors can modulate photochemical damage, in particular the common carotenoids present in food, which can be considered as potential prop hylactic agents against carcinogenesis. We investigated the effect of WA and B radiations on the skin of the SKH1 hairless mouse fed a diet either lacking in vitamin A or supplemented with retinol, beta-caroten e or astaxanthin. The latter is an oxygenated carotenoid (like canthax anthin) without provitamin A activity and with strong singlet oxygen q uenching ability. After analysing of vitamin status of each group (pla sma retinol concentrations and hepatic reserves), we searched for UV-i nduced modifications of polyamine metabolism by measuring epidermal or nithine decarboxylase (ODC) activity and free polyamines concentration (putrescine, spermidine and spermine). In the basal state without irr adiation, differences in ODC activity between groups were non signific ant; but after UV stimulation, ODC increased markedly in the skin of v itamin A-deficient animals, much more than in other groups. Curiously the addition of astaxanthin or beta-carotene to the regimen containing retinol reduced the protective effect of retinol alone. Regarding pol yamines after irradiation, putrescine was significantly increased in t he skin of deficient animals, in parallel with ODC activity. However a staxanthin had a stronger inhibitory effect on putrescine accumulation than retinol, and decreased spermidine and spermine concentrations: t his suggests a specific action on transglutaminases.