Figure 6.

Effects of oral administration of Pangasius hypophthalmus fish skin hydrolysates (fsCH) on ultraviolet-B (UV-B)-induced collagen loss of hairless mouse dorsal skin. SKH-1 hairless mice were exposed to UV-B radiation three times a week and treated with 2 mg/kg retinoic acid (RA) intraperitoneally and with 15 mg/kg glycine-proline-hydroxyproline tripeptide (GPH) and 206–412 mg/kg fsCH orally for eight weeks. Masson’s trichrome staining was performed with mouse dermal skin for collagen fibers stained in blue (A). For the measurement of dorsal skin tissue level of type 1 collagen in UV-B-irradiated SKH-1 hairless mice, immunohistochemical staining was conducted with an antibody against type 1 collagen (B). Each photograph is representative of four animals. Serum levels of procollagen type 1 carboxy-terminal propeptide (PICP) and procollagen type 1 amino-terminal propeptide (PINP) were measured by using ELISA kits (C,D). Values in bar graphs (mean ± SEM, n = 3) not sharing a small letter are different at p < 0.05.