Fig. 5

E. faecalis and E. faecium regulated dopa/dopamine and improved brain function in PD animals in the presence of BBR. a Treating mice with both MPTP (20 mg/kg/d, s.c.) and P (200 mg/kg/d, i.p.) for 7 days successfully generated the damage to brain function (LD, ***P < 0.001; LFR, ***P < 0.001) in the model mice. Carbidopa (1 mg/kg, s.c.) in combination with l-dopa (10 mg/kg/d, s.c.) for 6 days (from days 2 to 7) decreased the LD, cylinder test value (***P < 0.001, **P < 0.01), and increased the LFR (***P < 0.001); BBR (200 mg/kg/d, orally, days 2 to 7) significantly reduced the LD, cylinder test value (***P < 0.001, *P < 0.05), and elevated the LFR (*P < 0.05). Intravenous injection of BBR (10 mg/kg, for 6 days) did not cause a significant change in the LD, LFR, or cylinder test. b Levels of dopa/dopamine in the brain on day 7 of the experiment (mean ± SD, *P < 0.05 for dopa; **P < 0.01, ***P < 0.001 for dopamine). c Number of colonies from the mice treated with the antibiotics was significantly lower than that from the normal mice (mean ± SD, ***P < 0.001). d–f Translation of E. faecalis and E. faecium into the mice treated with antibiotics significantly increased dopa (L)/dopamine (R) levels in ICR mouse brains (d, *P < 0.05, **P < 0.01, NS no significance), blood (e, *P < 0.05, **P < 0.01), and feces (f, (L), (R), *P < 0.05, **P < 0.01, ***P < 0.001). g The relative abundance of Enterococcaeae in the fecal samples of clinical subjects increased after the two-month BBR treatment. Data are represented as the mean ± SD