Interestingly, no lower than 10 μM for acetate, 1 μM for propionate, and 0.1 μM for butyrate all triggered psychiatric disorder ACSS2 and its target TPH2 expressions at the mRNA and protein levels, indicating that physiological concentrations of acetate (within 171 μM), propionate (within 6 μM), and butyrate (within 2.8 μM) in the brain could induce expressions of ACSS2 and TPH2 (Fig. 1A and B and Fig. S1H to J). Here, TPH2 is linked to psychiatric disorder.