Abstract: Objective: To investigate the effect and mechanism of wheat peptide on improving cognitive capacity in chronic fatigue syndrome rats. Methods: A total of 70 male SD rats were used in this study. From these, ten were randomly selected as a normal control group (N), and the other 60 rats were used to construct an animal model of chronic fatigue syndrome (CFS) by chronic restraint combined with exhaustive swimming in cold water. Then, they were randomly divided into a model control group (M), a low-dose wheat peptide group (M + L), a medium-dose wheat peptide group (M + M) and a high-dose wheat peptide group (M + H). The rats in the M + L, M + M and M + H groups were orally administrated with wheat peptide at daily doses of 0.2, 0.4 and 0.8 g/(kg mb·d) body mass for eight consecutive weeks, respectively. After this, water maze test was carried out to evaluate the cognitive capacity of experimental rats. After completion of the test, the rats were killed to collect serum for detecting the levels of tryptophan, nerve growth factor (NGF) and brain-derived neurotropic factor (BDNF), and Th1 and Th2 cytokines by enzyme-linked immunosorbent assay (ELISA), and the level of oxidative stress and the content of 5-hydroxy tryptamine (5-HT) in hippocampus tissues were measured as well. Results: Compared with the control group, the escape latency, and the serum levels of MDA, tryptophan, 5-HT and Th2 cytokines (interleakin (IL)-4 and IL-10) in the CFS model rats were significantly increased (P < 0.05). On the contrary, the number of times that the rats crossed the platform quadrant, the time spent in the platform quadrant, superoxide dismutase activity, and the levels of nerve growth factor and brain-derived neurotropic factor and Th1 cytokines (TNF-β and IFN-γ) all significantly decreased (P < 0.05). All these symptoms were significantly improved after eight weeks of oral administration of wheat peptide intervention. Conclusion: Oral administration of wheat peptide can effectively improve cognitive function in CFS rats by activating the antioxidant system, regulating the secretion of neurocytokines and promoting cellular immune response resulting from the transformation from Th2-type cytokines to Th1-type cytokines.

Key words: wheat peptide; chronic fatigue syndrome; cytokine; cognition; antioxidant system