Ingestion of a collagen peptide containing high concentrations of prolyl-hydroxyproline and hydroxyprolyl-glycine reduces advanced glycation end products levels in the skin and subcutaneous blood vessel walls: a randomized, double-blind, placebo-controlled study.

In this randomized, double-blind, placebo-controlled study, we investigated the effects of collagen peptides (CP) containing high concentrations of prolyl-hydroxyproline and hydroxyprolyl-glycine on advanced glycation end products (AGEs) levels in the skin and subcutaneous blood vessel walls. A total of 31 individuals aged 47-87 years were randomly assigned to receive either 5 g/day of fish-derived CP or a placebo for 12 weeks. Body and blood compositions and AGEs levels were measured at the beginning and end of the study. No adverse events were observed, and both groups' blood and body compositions did not change significantly. However, the CP group had significantly lower AGEs levels and a slightly lower insulin resistance index (homeostasis model assessment ratio [HOMA-R]) than the placebo group. In addition, the percentage changes in AGEs and HOMA-R levels were positively and strongly correlated in both groups. These findings suggest that fish-derived CP may be effective in reducing AGEs levels and improving insulin resistance.

Monitoring urinary collagen metabolite changes following collagen peptide ingestion and physical activity using ELISA with anti active collagen oligopeptide antibody.

Active collagen oligopeptides (ACOP) are bioactive collagen-derived peptides detected by a recently-established ELISA. To facilitate studies of the function and metabolism of these products, this study aims to determine which of these peptides is recognized by a novel anti-ACOP antibody used in this ELISA. We then investigate the effect of collagen peptide (CP) ingestion and exercise on urinary ACOP concentrations in a cohort of university student athletes using colorimetric, LC-MS/MS, and ELISA. We observed that the antibody showed strong cross-reactivity to Pro-Hyp and Gly-Pro-Hyp and weak cross-reactivity to commercial CP. CP ingestion increased the urinary level of ACOP over time, which correlated highly with urinary levels of peptide forms of Hyp and Pro-Hyp. Physical activity significantly decreased the urinary ACOP level. This study demonstrates changes in urinary ACOP following oral CP intake and physical activity using ELISA with the novel anti-ACOP antibody. Thus, ACOP may be useful as a new biomarker for collagen metabolism.

Oral Administration of Collagen Hydrolysates Improves Glucose Tolerance in Normal Mice Through GLP-1-Dependent and GLP-1-Independent Mechanisms.

The aim of this study was to evaluate the antidiabetic properties of collagen hydrolysates (CHs). CHs exhibited dipeptidyl peptidase-IV inhibitory activity and stimulated glucagon-like-peptide-1 (GLP-1) secretion in vitro. We also determined whether CHs improve glucose tolerance in normal mice. Oral administration of CHs suppressed the glycemic response during the oral and intraperitoneal glucose tolerance tests (OGTT and IPGTT), but the effects were weaker in IPGTT than in OGTT. CHs had no effect on the gastric emptying rate. A pretreatment with the GLP-1 receptor antagonist, exendin 9-39 (Ex9), partially reversed the glucose-lowering effects of CHs, but only when coadministered with glucose. CHs administered 45 min before the glucose load potentiated the glucose-stimulated insulin secretion. This potentiating effect on insulin secretion was not reversed by the pretreatment with Ex9, it appeared to be enhanced. These results suggest that CHs improve glucose tolerance by inhibiting intestinal glucose uptake and enhancing insulin secretion, and also demonstrated that GLP-1 was partially involved in the inhibition of glucose uptake, but not essential for the enhancement of insulin secretion.

Differential modulation of gene expression among rat tissues with warm ischemia.

The aim of this study is to determine if warm ischemia after surgical extirpation impacts gene expression in tissue samples which will be used for cDNA array analysis. We investigated effects of warm ischemia on gene expression in lung, liver, kidney, and spleen of rats, chronologically, using an original cDNA array, real-time quantitative RT-PCR and immunohistochemistry. Although no visible alteration was found in RNA quality, cDNA array showed that expression of many genes was modulated by warm ischemia within 60 min in these tissues, 19.1% of the tested genes in lung, 11.0% in liver, 5.1% in kidney, and 16.2% in spleen. Quantitative RT-PCR revealed that warm ischemia significantly induced up-regulation of immediate early genes, c-fos, Egr-1, and c-jun, in lung, but not in liver. These findings suggest that genes may show tissue-dependent differential transcriptional response against warm ischemia. Tissue samples obtained from patients during surgery cannot completely escape effects of ischemia. In case of examination by cDNA array analysis, biologists should keep in mind that tissue samples come equipped with particular footprints.