It is well known that photoaged skin is characterized by increases in derma
l matrix components that include glycosaminoglycans, proteoglycans and mass
es of abnormal elastic fibers accompanied by substantial collagen loss. His
tochemical staining of such tissue gives the impression of "massive" loss o
f collagen and its replacement by these other matrix components. Early bioc
hemical studies have lent support to this notion with a reported decrease i
n total collagen of similar to 45% compared to protected skin. More recent
studies report considerably less, but varying, amounts of collagen loss, Ra
rely have the two approaches, histo-chemistry and biochemical analysis, bee
n used in the same study to examine the same tissue. In this study, collage
n loss was quantified biochemically in paired biopsies from sun-protected a
nd sun-exposed arm skin of moderately photoaged female subjects (age 51-77
years). The values obtained mere compared with histochemical and immunochem
ical findings. Quantitatively, collagen loss on a per mg protein basis mas
small compared to the histochemical appearance.