Silk Peptide Intake Increases Fat Oxidation at Rest in Exercised Mice

Abstract

250Obesity is associated with lifestyle habits such as inactivity, bad eating practices, stress and excessive net intake of calories (1). Among these, energy imbalance and inactivity are becoming serious problems. Total energy cost can be divided into three parts, including resting metabolic rate (RMR), diet-induced thermogenesis (DIT), and the amount of energy used for physical activity energy expenditure (AEE) (2). The greatest component of daily energy expenditure is RMR, constituting about 70% of the total energy expenditure (3, 4).Silk peptides (SP) have been ingested for a long time in Asian countries (5). In recent years, additional applications have been developed for silk, mainly in the field of biotechnology and biomedicine. The versatility of these new implementations arises from the singularity of the molecular structure of silk (6). Proteins such as fibroin and sericin are the main constituents of silk, with fibroin constituting 70 to 80% and sericin 20 to 30% of the total cocoon weight (6, 7).Many studies regarding the health benefits of SP intake have been reported (8-11). SP not only regulate blood glucose level and hyperlipidemia and but also decrease blood triglycerides and LDL cholesterol (12,13). In addition, a high dose (800 mg/kg) of SP was shown to exert stamina-enhancing activity in forced swimming mice by preventing tissue injuries and increasing anti-fatigue (14). Moreover, it is well known that increasing the concentration of leptin leads to an exothermic reaction and an increase in the amount of activity. Therefore, SP promotes fat oxidation and increases energy expenditure (15,16). Additionally, in several rat and mouse model studies, food intake and body weight were decreased in rodents fed ad libitum (5,14,16).However, measurements in those studies have been conducted for analysis of blood profiles and hormones in mice. Accordingly, we investigated the effects of SP administration using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for 24 h. Materials and MethodsAnimals. Seven-week-old male ICR-mouse (n518) were used. Mice were purchased from Orient Bio Inc. (Seongnam, Korea). All mice were housed in standard plastic cages under controlled conditions of humidity (50%) and temperature (2361˚C) with alternating 12 h cycles of light and dark. Mice were adapted to the laboratory housing conditions for 3 d. They were given free access to water and a non-purified commercial diet (5L79, Orient Bio Inc.) containing (g/kg diet): crude protein, 180; crude fat, 52; crude fiber, 52; minerals, 57; and carbohydrate, 368. The protein, fat, and carbohydrate ratio (%) based on calories was 21 : 14 : 65, and (Received January 11, 2013) Summary Silk peptides (SP) have been reported to decrease body weight and accumulate fat. We investigated the effects of SP administration by using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for the duration of 24 h. Seven-week-old male ICR-...

Red Ginseng Treatment for Two Weeks Promotes Fat Metabolism during Exercise in Mice

“…Respiratory gas was measured using an open-circuit apparatus based on previous studies [15,16]. The O 2 uptake and CO 2 production were measured using a mass analyzer (model RL-600, Alco System, Chiba, Japan; used a gas analyzers) and a switching system (model ANI6-A-S, Alco System).…”

High-Fat Diet Increases Fat Oxidation and Promotes Skeletal Muscle Fatty Acid Transporter Expression in Exercise-Trained Mice

“…At the end of the experimental protocol, the resting metabolic rate was measured by indirect calorimetry, using an open-circuit apparatus as previously described. [19][20][21][22] The flow rate was kept constant at 1.2 L/min and measured for 24 h. Mice had free access to food and water. O 2 uptake and CO 2 production were analyzed using a mass spectrometer (RL-600; Alco System, Chiba, Japan) and switching system (ANI6-A-S; Alco System).…”

“…Energy metabolism during exercise. After 12 weeks of endurance training, energy metabolism was measured during 1 h of running using an exercise metabolism chamber 20 under the training conditions of 15 m/min and a 12°slope.…”

Effect of Dietary Silk Peptide on Obesity, Hyperglycemia, and Skeletal Muscle Regeneration in High-Fat Diet-Fed Mice

“…A recent study showed that silk fibroin enhances insulin sensitivity and glucose uptake in 3T3-L1 adipocytes [31]. In addition, it has been shown that SP increases fat oxidation in exercising mice [32]. Finally, in our previous study, we demonstrated that SP has an anti-obesity effect by promoting beige-like adipocyte differentiation in WAT via AMP-activated protein kinase (AMPK) activation in high-fat diet (HFD)-induced obese mice [33].…”