This study aims to investigate the protective effect and potential mechanism of Jingfang Granules(JF) on the mouse model of chronic fatigue syndrome(CFS). Mice were randomized into normal, model, and low-, medium-, and high-dose(0.9, 1.8, and 3.6 g·kg~(-1)·d~(-1), respectively) JF groups according to the body weight. In addition to the normal group, other groups of mice received exhaustive swimming training and tail suspension training every day for the modeling of CFS. The mice in each administration group were administrated with JF at the corresponding dose by gavage, and those in the other groups were administrated with an equal amount of purified water. The exhaustive swimming and tail suspension tests were conducted in each group. The UV-glutamate dehydrogenase method was used to determine the serum level of urea nitrogen(UREA), and the lactate dehydrogenase(LDH) assay kit was used to determine the LDH level. Enzyme-linked immunosorbent assay was employed to measure the levels of interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) in the serum, muscle tissue, and brain tissue of mice in each group. Western blot was employed to determine the expression levels of Toll-like receptor 4(TLR4), myeloid differentiation factor 88(MyD88), nuclear factor-kappa B(NF-κB) and their phosphorylated proteins in the muscle tissue of mice. The 16S rDNA sequencing and ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) were adopted to detect the changes of intestinal flora and intestinal metabolites in mice. Compared with the model group, JF significantly prolonged the swimming exhaustion time and shortened the tail suspension time of the model mice, lowered the levels of LDH and UREA in the serum as well as the levels of IL-6 and TNF-α in the serum, muscle tissue, and brain tissue of CFS mice. In addition, JF down-regulated the expression of TLR4, MyD88, and p-NF-κB/NF-κB in the muscle tissue of CFS mice compared with the model group. The results of 16S rDNA sequencing demonstrated that JF ameliorated the intestinal flora disorder of CFS mice. The results of UPLC-MS/MS revealed that JF significantly affected the histidine metabolism pathway in the intestinal tract of CFS mice. Spearman analysis displayed that histamine, a metabolite involved in histidine metabolism, was negatively correlated with the abundance of Clostridia＿UCG-014, Dubosiella, and RF39 and positively correlated with the abundance of Coriobacteriaceae＿UCG-002. The metabolite imidazole-4-acetaldehyde was negatively correlated with the abundance of Clostridia＿UCG-014, Dubosiella, and RF39 and positively correlated with the abundance of Coriobacteriaceae＿UCG-002. In conclusion, JF can increase the swimming exhaustion time, reduce the immobility time of tail suspension, lower serum LDH and UREA levels, and alleviate inflammation response. It may exert the therapeutic effect by improving intestinal flora homeostasis and inhibiting histidine metabolism by down-regulating the expression of proteins in the TLR4/MyD88/NF-κB signaling pathway, thereby relieving the symptoms of CFS in mice.
Keywords: Jingfang Granules; chronic fatigue syndrome; inflammation; intestinal flora; non-targeted metabolomics.