SEOUL, Korea—According to a recent study published in the Journal of Dermatological Science, intrinsic aging- and photoaging-dependent glycosaminoglycan (GAG) changes and their correlations with water content provide new insights into the pathophysiology of dry skin in the elderly (2011;62(3):192-201). GAGs have various structural and physiological regulatory functions in skin, including tissue water maintenance, due to their high water-holding capacity. Therefore, researchers investigated changes of GAGs during intrinsic aging and photoaging of human skin and their correlations with water content.
Samples of sun-protected buttock and sun-exposed forearm skin were obtained from young male (21 to 30 years, n=8) and female (20 to 33 years, n=8) subjects, as well as old male (70 to 78years, n=8) and female (70 to 80years, n=8) subjects, and their epidermal and dermal contents of hyaluronic acid (HA), total sulfated GAG (tsGAG), total uronic acid (tUA) and tissue water were measured. HA content was determined by enzyme-linked immunosorbent assay using HA-binding protein, tsGAG by the sulfated GAG assay kit using 1,9-dimethylmethylene blue, tUA by carbazole reaction, and tissue water by subtraction of tissue dry weight from wet weight.
In the buttock, HA was higher in dermis than in epidermis, while tsGAG and tUA were higher in epidermis. In intrinsically aged buttock, epidermal HA and dermal tsGAG and tUA decreased. However, when analyzed for each gender, epidermal tsGAG, tUA and tissue water decreased only in females. Forearm/buttock ratios of each molecule were compared for determination of photoaging-dependent changes. Forearm/buttock ratios of HA, tsGAG, tUA and tissue water increased in aged dermis, but showed no change in aged epidermis. When analyzed for each gender, ratios of epidermal HA and tissue water increased only in aged females, while ratios of epidermal tsGAG, tUA and tissue water decreased only in aged males. Correlations of water content with HA, tsGAG and tUA were found in epidermis, but not with tsGAG in dermis.