ABSTRACT
ABSTRACT The human skin aging process is a complex mechanism that can be induced both by intrinsic and extrinsic factors. Observations include a decrease in the biosynthetic and proliferative capacity of cells, increased expression of matrix metalloproteinases, reduction in collagen type I expression, and the progressive disappearance of elastic tissue in the papillary dermis. L-arginine, the substrate of nitric oxide synthesis, is involved in angiogenesis and cell proliferation, as well as an indirect precursor of collagen synthesis via the proline pathway. The aim of this study was to examine the tensile strength, histology, and immunohistochemistry of female and male mice skin receiving different concentrations of topically applied L-arginine, in order to evaluate the possibility of using L-arginine as an active cosmetic ingredient in antiaging products. The results suggest that the application of L-arginine improves the mechanical resistance of skin from older female mice (20 weeks old) and promotes the formation of a larger amount of collagen and elastic fibers in the skin when applied at a concentration of 15%.