Effects of Silk Peptides Administration on Fat Utilization Over a Whole Day in Mice

Abstract

[Purpose]The aim of the present study was to investigate the effects of treatment with silk peptides (SP) on resting energy expenditure over a 24-h period and clarify the molecular mechanism underlying its enhancement of fat utilization in mouse skeletal muscles.[Methods]Sixteen male ICR mice (6-weekold) were divided into two groups and treated with distilled water and SP (CON and SP treatment groups, respectively). SP were dissolved in distilled water and administered to the SP group at 800 mg/kg while the CON group was administered distilled water orally daily for 2 weeks. Resting metabolic rate (RMR) was measured before and after SP ingestion for 2 weeks using an open circuit calorimetry system. After the treatments, we collected blood and skeletal muscle samples from the mice.[Results]Final body weight and body weight gain showed no significant difference in the CON and SP groups. Conversely, food intake was significantly lower in the SP group than it was in the CON group. The comparison of the respiratory exchange rate (RER) at various time points after the 2-week treatment revealed that it was significantly lower in the SP group than it was in the CON group at 9, 15, 16, and 18-22 h (Figure 3 B). The sum of the RER over 24-h was lower in the SP group than it was in the CON group, but the difference was not statistically significant. The protein levels of fatty acid translocase (FAT)/ cluster of differentiation 36 (CD36) were approximately 12% higher in the SP group than they were in the CON group but that of carnitine palmitoyltransferase I (CPTІ) was not significantly different between the two groups.[Conclusion]These results suggest that treatment with SP 800 mg/kg for 2 weeks may promote fat utilization during physical activity, but not the entire day. In addition, SP treatment effectively enhanced FAT/CD36 protein level in skeletal muscle. In future investigations, it would be necessary to elucidate the effects of long-term SP intake on the resting metabolism of both animals and humans.

Comparative analysis of basal locomotor activity-related metabolic phenotypes between C57BL/6 mice and ICR mice substrains derived from three different sources

“…The resting metabolic rate (RMR), which serves as an approximation of the metabolic phenotype, was measured at 8 and 16 weeks of age. Measurements were performed for 24 hours as previously described [ 16 ] in a metabolic chamber with an open-circuit system (WSMR-1400, Westron, Japan). In order to reduce stress, the mice were transferred to the chamber two hours before measurement initiation.…”

Dietary Silk Peptide Prevents High-Fat Diet-Induced Obesity and Promotes Adipose Browning by Activating AMP-Activated Protein Kinase in Mice

“…Dietary SP is a natural material isolated from Bombyx mori that is known to have effects on metabolism [27,47]. In recent studies, it is reported that hydrolyzed proteins are efficiently absorbed in the small intestine [48].…”

Effects of taurine and ginseng extracts on energy metabolism during exercise and their anti-fatigue properties in mice

“…The mice were placed in exercise metabolism chambers for adaptation 1 h before the experiment. Respiratory gas was measured using an open-circuit apparatus in accordance with the methods proposed in previous studies [ 25 26 ].…”