Effect of orally administered collagen peptide on granulation tissue collagen content in an aged rat model

Abstract

Collagen synthesis declines with aging. Low protein diet fed rats can be used as a model for aged rats. In the present experiments, we evaluated the collagen content of granulation tissue after oral administration of collagen peptide in aged rats. After administration of 0.2, 1.0 or 5.0 g×kg -1 body weight collagen peptide for 1 week, weight and hydroxyproline (HYP) content of the granulation tissue were increased in a dose-dependent manner. To directly investigate the collagen content of granulation tissue, collagen was stained with Sirius red/Fast green. Histological analysis clarified that 1.0 g×kg-1 body weight of collagen peptide increased collagen fiber content in the granulation tissue. Furthermore, we compared the effects of several food-derived peptides or protein on collagen content. All peptides and protein (1.0 g×kg-1 body weight) increased weight and HYP content of granulation tissue in aged rats. Interestingly, orally administrated collagen peptide was the most effective in increasing weight and HYP content of granulation tissue. These results indicated that oral administration of collagen peptide is effective for increasing collagen content in an aged rat model.