FFAR3 and Parkinson disease: Ni and colleagues used 16S rRNA sequencing and transcriptomic analyses to show that fecal microbiota transplantation in MPTP-induced PD mice significantly restored motor function, increased striatal dopamine and serotonin levels, and elevated the expression of SCFA receptors (FFAR2 and FFAR3), pointing to a causal role of SCFAs, particularly acetate, propionate, and butyrate, in modulating neuroinflammation and neuronal survival [66].