Hyaluronic acid and dermatan sulfate are selectively stimulated by retinoic acid in irradiated and nonirradiated hairless mouse skin

All-trans retinoic acid (RA) has been shown to enhance subepidermal repair in photoaged hairless mice. The current study assesses the effects of RA on the glycosaminoglycan (GAG) content in irradiated and nonirradiated mouse skin. Mice were exposed to ultraviolet B (WB) for 10 wk, after which they were treated either with 0.05% RA or with an ethanol-polyethylene glycol 400 vehicle three times a week for 10 or 20 wk. When assessed at the end of 10 wk of UVB irradiation, the GAG content had doubled, without a change in the hyaluronic acid (HA) to dermatan sulfate (DS) ratio. When irradiation was discontinued, the GAG content decreased progressively until the end of the experimental period, This decline was totally inhibited by RA treatment and could be ascribed to a marked increase in hyaluronic acid (78%), whereas no significant change in DS was observed, In nonirradiated skin, however, topical RA increased GAG levels mainly by a pronounced increase in the content (50%) and the synthesis (40%) of DS, In untreated mice, the HA/DS ratio decreased significantly with age in both irradiated and nonirradiated mice, Interestingly, RA maintained this ratio only in animals exposed to UVB. In addition, there was a marked stimulation in the heparin content, up to similar to 20-fold, after irradiation, whereas the amount of heparin in both irradiated and nonirradiated skin increased about 2- to 3-fold with RA treatment. In summary, the alterations induced in HA and DS contents in irradiated and nonirradiated skin indicate the specificity of the RA-induced effects for the various GAGs.