Abstract
Fatigue can lead to several health issues and is particularly prevalent among elderly individuals with chronic inflammatory conditions. Ninjin'yoeito, a traditional Japanese herbal medicine, is used to address fatigue and malaise, anorexia, and anemia. This study aimed to examine whether relieving inflammation in the brain and skeletal muscle of senescence-accelerated mice prone 8 (SAMP8) could reduce fatigue-like conditions associated with aging. First, SAMP8 mice were divided into two groups, with and without ninjin'yoeito treatment. The ninjin'yoeito-treated group received a diet containing 3% ninjin'yoeito for a period of 4 months starting at 3 months of age. At 7 months of age, all mice underwent motor function, treadmill fatigue, and behavioral tests. They were then euthanized and the skeletal muscle weight, muscle cross-sectional area, and concentration of interleukin (IL)-1β and IL-1 receptor antagonist (IL-1RA) in both the brain and skeletal muscle were measured. The results showed that the ninjin'yoeito-treated group had higher motor function and spontaneous locomotor activity than the untreated group did and ran for significantly longer in the treadmill fatigue test. Moreover, larger muscle cross-sectional area, lower IL-1β concentrations, and higher IL-1RA concentrations were observed in both the brain and skeletal muscle tissues of the ninjin'yoeito-treated group than in the untreated group. The results suggest that ninjin'yoeito improves age-related inflammatory conditions in both the central and peripheral tissues and reduces fatigue.