This study investigated the anti-obesity effects of collagen peptide derived from skate skin on lipid metabolism in high-fat diet (HFD)-fed mice. All C57BL6/J male mice were fed a HFD with 60% kcal fat except for mice in the normal group which were fed a chow diet. The collagen-fed groups received collagen peptide (1050 Da) orally (100, 200, or 300 mg/kg body weight per day) by gavage, whereas the normal and control groups were given water (n = 9 per group). The body weight gain and visceral adipose tissue weight were lower in the collagen-fed groups than in the control group (p < 0.05). Plasma and hepatic lipid levels were significantly reduced by downregulating the hepatic protein expression levels for fatty acid synthesis (sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC)) and cholesterol synthesis (SREBP-2 and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR)) and upregulating those for β-oxidation (peroxisome proliferator-activated receptor alpha (PPAR-α) and carnitine palmitoyltransferase 1 (CPT1)) and synthesis of bile acid (cytochrome P450 family 7 subfamily A member 1 (CYP7A1)) (p < 0.05). In the collagen-fed groups, the hepatic protein expression level of phosphorylated 5′ adenosine monophosphate-activated protein kinase (p-AMPK) and plasma adiponectin levels were higher, and the leptin level was lower (p < 0.05). Histological analysis revealed that collagen treatment suppressed hepatic lipid accumulation and reduced the lipid droplet size in the adipose tissue. These effects were increased in a dose-dependent manner. The findings indicated that skate collagen peptide has anti-obesity effects through suppression of fat accumulation and regulation of lipid metabolism.
The protective effects of a chondroitin sulfate-rich extract (CSE) from skate cartilage against lipopolysaccharide (LPS)-induced hepatic damage were investigated, and its mechanism of action was compared with that of chondroitin sulfate (CS) from shark cartilage. ICR mice were orally administrated 200 mg/kg body weight (BW) of CS or 400 mg/kg BW of CSE for 3 consecutive days, followed by a one-time intraperitoneal injection of LPS (20 mg/kg BW). The experimental groups were vehicle treatment without LPS injection (NC group), vehicle treatment with LPS injection (LPS group), CS pretreatment with LPS injection (CS group), and CSE pretreatment with LPS injection (CSE group). Hepatic antioxidant enzyme expression levels in the CS and CSE groups were increased relative to those in the LPS group. In LPS-insulted hepatic tissue, inflammatory factors were augmented relative to those in the NC group, but were significantly suppressed by pretreatment with CS or CSE. Moreover, CS and CSE alleviated the LPS-induced apoptotic factors and mitogen-activated protein kinase (MAPK). In addition, CS and CSE effectively decreased the serum lipid concentrations and downregulated hepatic sterol regulatory element-binding proteins expression. In conclusion, the skate CSE could protect against LPS-induced hepatic dyslipidemia, oxidative stress, inflammation, and apoptosis, probably through the regulation of MAPK signaling.
The aim of this study was to investigate and development collagen peptide materials from skate skin. Protein and fat content of collagen peptide showed about 95% and 0.1%, respectively. Average molecular weight of collagen peptide was measured as 1,015. In the analysis of amino acid, glycine and hydroxy proline content in collagen peptide was 19.32% and 16.25%, respectively, showing a typical characteristics of the collagen peptide. In obese db/db mice ingested 500 mg/day of collagen peptide for 18 days, the amounts of food and water intake were decreased considerably, contents of triglyceride, total cholesterol were decreased significantly in white adipose tissue of db/db mice. The final yield of collagen peptide was 17.23% in the optimized process for mass production. These results indicate that collagen peptide from skate skin may serve as candidates of fat reduction in adipose tissue and could be used as functional food and cosmetic ingredients.
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