Fig. 1

Gut microbiota from patients with ET exhibited a lower GABA-producing capacity. a Orthogonal partial least-squares discriminant analysis (OPLS-DA) score plot of fecal neurotransmitter levels in patients with ET and healthy individuals (controls). b Important neurotransmitters (GABA and TrpA) identified by OPLS-DA based on variable importance in projection (VIP) scores. c Relative levels of fecal GABA. d Principal coordinate analysis (PCoA) of microbiota composition at the generic level. e Expression of GAD (glutamate decarboxylase) in gut microbiota. f Heatmap indicating the correlations between the expression levels of genes encoding GABA-related enzymes and fecal neurotransmitter levels. 5-HIAA, 5-hydroxyindole-3-acetic acid; 5-HT, serotonin hydrochloride; Ach, acetylcholine chloride; AMADH, γ-aminobutyraldehyde dehydrogenase; DA, hydroxytyramine hydrochloride; DOPA, levodopa; E, adrenaline hydrochloride; ET, essential tremor; GABA, γ-aminobutyric acid; GABA-T, γ-aminobutyric acid transaminase; GAD, glutamate decarboxylase; Gln, L-glutamine; Glu, L-glutamic acid; HC, healthy controls; His, L-histidine; HisA, histamine; Kyn, DL-kynurenine; KynA, kynurenic acid; PAO, polyamine oxidase; SSADH, succinic semialdehyde dehydrogenase; Trp, L-tryptophan; TrpA, tryptamine; Tyr, L-tyrosine; TyrA, tyramine. Box plots indicate the median and interquartile range. ^*P < 0.05; ^**P < 0.01