The intestinal microbiota exerts a sex-specific influence on neuroinflammation in a Parkinson's disease mouse model

Parkinson's disease (PD) is a neurodegenerative disorder characterised by chronic and progressive symptoms; it is more prevalent in men than in women. The sex-specific influence of the intestinal microbiota has been associated with some neurodegenerative diseases, but the relationship with PD is currently unclear. In this study, we treated mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish a PD mouse model, and we utilised an antibiotic cocktail (Abx) to deplete the intestinal microbiota to evaluate the influence of the intestinal microbiota on male and female PD mice. MPTP treatment obviously caused bradykinesia and low mobility in female and male mice. Meanwhile, Abx treatment exerted a greater effect on male mice than female mice. Western blotting and immunofluorescence revealed that male mice treated with MPTP had higher expression of α-synuclein and proteins related to neuroinflammation and intestinal inflammation based on activation of glial cells and the TLR4–MyD88 signalling pathway. The sex-specific differences could be due to the different composition of the intestinal microbiota. Specifically, female mice had significantly higher abundance of Allobaculum, Turicibacter and Ruminococcus than male mice. Moreover, the abundance of the probiotic genus Bifidobacterium showed opposite trends in male and female mice. Our results indicate that the intestinal microbiota has an important effect on PD mice, especially male mice, by influencing neuroinflammation through the microbiota–gut–brain axis. In the future, there should be a focus on providing more reliable evidence for the pathogenesis and precise treatment of PD.