ANALYSIS OF CONNECTIVE-TISSUE MACROMOLECULAR COMPONENTS IN ISHIBASHI RAT SKIN - ROLE OF COLLAGEN AND ELASTIN IN CUTANEOUS AGING

The Ishibashi (IS) rat, established from cross-breeding between Wistar and wild rats, has a unique skin appearance, with wrinklings and furr ows indicative of skin aging appearing at the age of 12 weeks. To unde rstand the underlying mechanism of the formation of wrinkles, macromol ecular components of connective tissue, collagen and elastin, in the y oung (5-6-week-old) and the aged (23-30-week-old) IS rat skins were bi ochemically analyzed. Hydroxyproline and isodesmosine contents in the aged IS rats were reduced 22% (P < 0.05) and 37% (P < 0.05) compared t o the young rats, whereas no significant differences in the contents o f both macromolecules in control Sprague-Dawley (SD) rats were seen. T he relative content of type III collagen was unaltered between the you ng and aged skins of both IS and SD rats. A relative decrease in the i ntact elastin molecule (65 kDa) and a relative increase in the elastin fragments with lower molecular weights were observed in the aged IS r at skin by immunoblotting method. These results indicate that the redu ction in collagen and elastin contents and increased degradation of el astin molecules in the aged IS rat skin could be related to the format ion of wrinkles. Thus, the IS rat may provide a useful model for the s tudy of skin aging.