title: The anti-fatigue effects of the low-molecular-weight fraction of bonito extract in mice.
abstract: Bonito extract (BE), a hot-water extract of bonito muscle, has traditionally been considered as a folk remedy for fatigue. In this study we investigated the effects of BE on physical fatigue. BE was divided into, high, mid, and low-molecular-weight fractions (LMF), to explore the effectiveness of BE compounds. The swimming times to exhaustion of mice administered 0.86 g/kg BE and those administered 0.86 g/kg LMF were significantly longer than those of the vehicle-treated mice in a forced swimming model, indicating that BE possesses an anti-fatigue effect and that the LMF contributes to this effect. The LMF was also confirmed to aid the recovery of locomotor activity after physical fatigue in a forced walking model. We also examined respiratory gas levels and found that oxygen consumption and lipid oxidation were significantly greater in the group administered LMF than in the vehicle group, indicating that LMF promotes the utilization of fatty acids as an energy source. To elucidate why the mice administered LMF showed an anti-fatigue effect, we evaluated metabolic variables during exercise. The concentrations of nonesterified fatty acids and ketone bodies were higher, whereas serum and muscle lactic acid levels were lower in the mice administered LMF than in those in the vehicle group after the start of swimming. When the results were taken as a group they indicated that the effect of BE administration on improving endurance capacity was mediated, at least partly, by an increased utilization of lipids as a source of energy during exercise.
authors.affiliation: Research Institute for Health Fundamentals, Ajinomoto Co., Inc. , Kawasaki, Japan. yoshizu_nozawa@ajinomoto.com
authors.forename: Yoshizu
authors.initials: Y
authors.lastname: Nozawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Yuki
authors.initials: Y
authors.lastname: Okabe
authors.forename: Taichi
authors.initials: T
authors.lastname: Ishizaki
authors.forename: Motonaka
authors.initials: M
authors.lastname: Kuroda
mesh_terms: D000818:Animals; D005591:Chemical Fractionation; D005221:Fatigue / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D005223:Fats / Q000378:metabolism; D008297:Male; D051379:Mice; D008970:Molecular Weight; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000737:chemistry; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D014020:Tissue Extracts / Q000737:chemistry / Q000627:therapeutic use*; D014413:Tuna
chemical_list: D005223:Fats; D014020:Tissue Extracts