Study on Effects of Soybean Protein and Soybean Peptides on Anxiety-Like Behavior in Mice

To study the effects of soybean protein and soybean peptides on anxiety-like behavior induced by chronic unpredictable mild stress (CUMS) in mice, forty male C57BL/6J mice aged 6-7 weeks were selected and randomly divided into a control group, a model group, a soybean protein group, and a soybean peptides group. The mice were induced to develop anxiety-like behaviors by CUMS and were subjected to an elevated plus maze test on 53 d. Brain tissue samples were collected on 54 d to examine the activation of microglia, the levels of inflammatory factors and brain-derived neurotrophic factor (BDNF), and the expression of related proteins on the BDNF-TrkB-CREB pathway. The results showed that compared with the control group, CUMS resulted in a significant decrease in the percentage of time spent in the open arms and numbers of entries into the open arms, a significant increase in the number of Iba-1 positive cells, a significant increase in the level of the IL-1β, and a significant decrease in the expression of BDNF, p-TrkB, and p-CREB in mice (P<0.05). Compared with the model group, the percentage of entries into the open arms of mice in the soybean protein group was 1.4 times higher than that in the model group, while IL-6, IL-1β, TNF-α, and IFN-γ levels were reduced by 21.5%, 34.2%, 10.9%, and 32.5%, respectively, and BDNF protein expression was increased by 39.8% (P<0.05). In the soybean peptides group, the percentage of time spent in the open arms and numbers of entries into the open arms of mice were 2.0 and 1.4 times higher than those in the model group, while the number of Iba-1-positive cells in the hippocampus, CA1, and CA3 regions of the mice decreased by 39.0%, 43.2%, and 40.8%, respectively, the levels of IL-10 were increased by 23.3%, and the levels of IL-1β and TNF-α were decreased by 26.8% and 13.7%, respectively. BDNF levels increased by 22.0%, and BDNF and p-TrkB protein expression increased by 63.0% and 42.5%, respectively (P<0.05). The results of the study suggested that both soybean protein and soybean peptides nutritional interventions could alleviate neuroinflammation and enhance neurotrophic function, thereby exert anxiolytic activity, with soybean peptides having more significant effects. The study aimed to provide theoretical references for the development and utilization of anxiolytic foods.