Fecal transplantation can alleviate tic severity in a Tourette syndrome mouse model by modulating intestinal flora and promoting serotonin secretion

BACKGROUND: : Tourette syndrome (TS) is a neuropsychiatric disorder with onset in childhood that warrants effective therapies. Gut microbiota can affect central physiology and function via the microbiota–gut-brain axis. Therefore, the gut microbiota plays an important role in some mental illnesses. A small clinical trial showed that fecal microbiota transplantation (FMT) may alleviate TS symptoms in children. Herein, FMT effects and mechanisms were explored in a TS mouse model. METHODS: : TS mice model (TSMO) (n = 80) were established with 3,3′-iminodipropionitrile, and 80 mice were used as controls. Mice were grouped into eight groups and were subjected to FMT with feces from children or mice with or without TS, or were given probiotics. Fecal specimens were collected 3 weeks after FMT. 16S rRNA sequencing, behavioral observation, and serum serotonin (5-HT) assay were performed. Differences between groups were analyzed using Mann-Whitney U test and Kolmogorov-Smirnov (KS) tests. RESULTS: : A total of 18 discriminative microbial signatures (linear discriminant analysis score > 3) that varied significantly between TS and healthy mice (CONH) were identified. A significant increase in Turicibacteraceae and Ruminococcaceae in TSMO after FMT was observed (P < 0.05). Compared with non-transplanted TSMO, the symptoms of those transplanted with feces from CONH were alleviated (W = 336, P = 0.046). In the probiotic and FMT experiments, the serum 5-HT levels significantly increased in TSMO that received probiotics (KS = 1.423, P = 0.035) and in those transplanted with feces from CONH (W = 336.5, P = 0.046) compared with TSMO without transplantation. CONCLUSIONS: : This study suggests that FMT may ameliorate TS by promoting 5-HT secretion, and it provides new insights into the underlying mechanisms of FMT as a treatment for TS.