In the present study, we identified several food-derived collagen peptides in human blood after oral ingestion of some gelatin hydrolysates. Healthy human volunteers ingested the gelatin hydrolysates (9.4-23 g) from porcine skin, chicken feet, and cartilage after 12 h of fasting. Negligible amounts of the peptide form of hydroxyproline (Hyp) were observed in human blood before the ingestion. After the oral ingestion, the peptide form of Hyp significantly increased and reached a maximum level (20-60 nmol/mL of plasma) after 1-2 h and then decreased to half of the maximum level at 4 h after the ingestion. Major constituents of food-derived collagen peptides in human serum and plasma were identified as Pro-Hyp. In addition, small but significant amounts of Ala-Hyp, Ala-Hyp-Gly, Pro-Hyp-Gly, Leu-Hyp, Ile-Hyp, and Phe-Hyp were contained.

Collagen, a major extracellular matrix macromolecule, is widely used for biomedical purposes. We investigated the absorption mechanism of low molecular weight collagen hydrolysate (LMW-CH) and its effects on osteoporosis in rats. When administered to Wistar rats with either [(14)C]proline (Pro group) or glycyl-[(14)C]prolyl-hydroxyproline (CTp group), LMW-CH rapidly increased plasma radioactivity. LMW-CH was absorbed into the blood of Wistar rats in the peptide form. Glycyl-prolyl-hydroxyproline tripeptide remained in the plasma and accumulated in the kidney. In both groups, radioactivity was retained at a high level in the skin until 14 days after administration. Additionally, the administration of LMW-CH to ovariectomized stroke-prone spontaneously hypertensive rats increased the organic substance content and decreased the water content of the left femur. Our findings show that LMW-CH exerts a beneficial effect on osteoporosis by increasing the organic substance content of bone.

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Femur bone densities and tibialis anterior muscle properties of type II collagen-induced arthritic mice were determined. Furthermore, voluntary running activities of arthritic mice were compared with those of controls. Arthritis was induced by an intradermal injection of type II collagen in the adjuvant. Body and muscle weights were lower in arthritic mice than in controls. Cortical and trabecular bone densities and muscle fiber crosssectional areas were decreased by arthritis. After classifying the arthritic severity into slight, intermediate, and severe levels based on the degree of knuckle swelling, cortical and trabecular bone densities, fiber cross-sectional areas, and fiber succinate dehydrogenase activities were lowest when arthritis was most severe. Furthermore, arthritic mice, especially those with intermediate and severe levels, showed lower voluntary running activities. These findings indicate that lower bone density and muscle atrophy of type II collagen-induced arthritic mice are related to arthritic severity and decreased motor activity.Key words : bone density, cross-sectional area, motor activity, mouse, muscle fiber, succinate dehydrogenase activity, type II collagen-induced arthritis.Degeneration in the musculoskeletal system, including muscle atrophy and bone osteoporosis, is widely accepted as being induced by aging [1][2][3][4][5], hind-limb suspension [6][7][8], or exposure to microgravity [9][10][11][12]. These changes are considered to result from decreased motor activity.Previous studies observed that animal models [13-16] and patients [17] with arthritis showed decreased spontaneous motor activities because of severe chronic pain in the joints. Type II collagen-induced arthritis is a model of polyarthritis induced in susceptible rodents by immunization with type II collagen [18,19]. Muscle atrophy and decreased bone density occur in type II collageninduced arthritic rodents because these animals may have lower motor activities as a result of their distal joint pain. Therefore this study investigated cortical and trabecular bone densities of the femur and fiber cross-sectional areas and succinate dehydrogenase (SDH) activities of the tibialis anterior muscle in type II collagen-induced arthritic mice. Furthermore, voluntary running activities of arthritic mice were compared with those of controls. METHODSAll experimental procedures and animal care were conducted in accordance with the Guide for the Care and Use of Laboratory Animals prepared by the Physiological Society of Japan. This study was also approved by the Institutional Animal Care and Use Committee of Kyoto University.Antigens and immunizations. Sixty-day-old DBA/1J male mice were randomly divided into control ( n = 5) and arthritic ( n = 13) groups. All mice were individually housed in cages of the same size. The mice in the arthritic group were immunized from 60 to 81 days after birth. Type II collagen was solubilized from fetal bovine articular cartilage by limited proteolysis with pepsin [20]. Type II collagen was...

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SummaryThe effects of the low-molecular-weight fraction of Papain-hydrolyzed pork meat (LMF) on the plasma cholesterol level and the generation of atherosclerosis were stud ied in rabbits fed a cholesterol-enriched diet. In LMF-fed rabbits, the plasma and liver choles terol concentrations were both significantly lower (p<0.01) than in rabbits fed untreated pork meat (PM). Similarly, the cholesterol concentrations of the chylomicron and VLDL fractions were significantly lower in LMF-fed rabbits than in rabbits fed PM. Deposition of lipid in transverse sections of the aortic arch was significantly less in rabbits fed LMF than in those fed PM. Electron microscopic studies revealed preventive effects against premature atherosclerotic lesions in the aorta of rabbits fed LMF. These results indicate that LMF has a hypocholesterolemic action and preventive effects against premature atherosclerosis. Key Words New Zealand white rabbits, papain-hydrolyzed pork meat, plasma choles terol, liver cholesterol, premature atherosclerosis Many epidemiological, biochemical, and clinical studies have demonstrated that hypercholesterolemia is one of the most important risk factors for atherosclero sis, which is responsible for coronary heart disease. It is important to improve dietary conditions and/or to de velop new dietary materials if we are first to lower the high level of plasma cholesterol seen in many persons among the general population, then to keep it within the desirable range. Dietary proteins and fat, are impor tant factors in determining the plasma cholesterol level. In animals and humans, soy protein has been shown to be more effective than casein at reducing the serum cholesterol level (1-5). After Sugano et al. (5,6) had found that a protease hydrolyzate of isolated soy protein had a more marked hypocholesterolemic effect than undigested soy protein, Morimatsu et al. (7,8) reported that a papain hydrolyzate of pork meat produced a greater suppression of the plasma cholesterol level than soy protein did in rats with dietary-induced hypercho lesterolemia. The rat, however, is less sensitive to a cho lesterol-rich diet than the rabbit is, and it is difficult to induce a distinct atherosclerosis in the former species