[Advances in Parkinson's disease induced by α-synuclein transmitted through the gut-brain axis]

Parkinson's disease (PD) is the most common neurodegenerative disease. Along with the population aging of China, the increase of PD patients in China will result in serious economic and medical burdens. The typical pathological characteristics of PD are the death of dopaminergic neurons in the substantia nigra compacta and the pathological inclusion bodies formed by abnormally aggregated amyloid alpha-synuclein (α-Syn) in dopaminergic neurons, which is also named as Lewy body. Studies have found that the Lewy body exists not only in the central nervous system, but also in the peripheral nervous system. The abundant enteric nervous system in the gut is called the "second brain". The discovery of the gut-brain axis also proves that α-Syn can be transmitted bilaterally between the brain and the gut. The gut microbiota was shown to be involved in the formation and transmission of pathological α-Syn. Therefore, this article summarized the bilateral transmission relationship of α-Syn in the brain and the gut and illustrated the influence of gut microbiota on the abnormal aggregation of α-Syn. Combined with the current progresses on PD patients and animal models especially the non-human primate experiments, this article aimed to provide a reference for the screening and diagnosis of PD.