Polygonatum sibiricum ameliorated cognitive impairment of naturally aging rats through BDNF–TrkB signaling pathway

Cognitive dysfunction is high in the elderly population and seriously affects the quality of life. Brain‐derived neurotrophic factor (BDNF) is one of the key neurotrophic proteins, and activation of BDNF–TrkB is considered an effective strategy to improve cognitive dysfunction during aging. In this study, administration of polygonatum sibiricum (PS) for 5 months effectively ameliorates the cognitive function, improving the Nissl body state in cortex and hippocampus in aging rats. In addition, PS can improve the synaptic structure and increase the number of synapses. Furthermore, PS reverses the reduction of synaptic plasticity‐related proteins postsynaptic density protein 95 (PSD‐95) and synaptophysin during aging and up‐regulates the expression of BDNF–TrkB. In conclusion, PS improves cognitive dysfunction and enhances synaptic plasticity in naturally aged rats by regulating the BDNF–TrkB signaling pathway. PS has the potential to be developed as a novel and promising functional health food for the elderly. Practical applications Polygonatum sibiricum (PS) is a traditional Chinese medicine, which has been included in the homologous plant of medicine and food. PS has been widely used to treat lung diseases, diabetes and antiaging in clinical. Studies have confirmed that PS can accelerate the repair and regeneration of damaged neurons, reverse the changes in synaptic structure, and improve the ability of learning and memory. Our study confirmed that PS significantly improved the cognitive function in aging rats. PS has great potential to be developed as a functional food for improving neurological function and anti‐aging. In this study, we demonstrated that polygonatum sibiricum effectively ameliorated the spatial learning and memory function of naturally aging rats. In addition, polygonatum sibiricum can improve neuronal function, increase the number of synapses in aging rats and enhance structural integrity. The underlying mechanism is mainly related to PS increases the expression of BDNF–Trkb signaling pathway and enhances synaptic plasticity.