MGB	Microbiota–gut–brain
SCFAs	Short-chain fatty acids
BDNF	Brain-derived neurotrophic factor
GF	Germ-Free
MDD	Major depressive disorder
AHN	Adult hippocampal neurogenesis
DG	Dentate gyrus
HPA	Hypothalamic–pituitary–adrenal
mPFC	Medial prefrontal cortex
GABA	Gamma-aminobutyric acid
fMRI	Functional magnetic resonance imaging
5-HT	Serotonin
DA	Dopamine
NE	Norepinephrine
ENS	Enteric nervous system
MRIs	Structural magnetic resonance imaging
DTI	Diffusion tensor imaging
EEG	Electroencephalogram
BBB	Blood–brain barrier
ASD	Autism spectrum disorders
ADHD	Attention deficit hyperactivity disorder
EECs	Enteroendocrine cells
PAMPs	Pathogen-associated molecular patterns
CNS	Central nervous system
NTS	Nucleus of the solitary tract
DMV	Dorsal motor nucleus of the vagus nerve
TNF	Tumor necrosis factor
LPS	Lipopolysaccharide
TLRs	Toll-like receptors
IL-1β	Interleukin-1 beta
IL-6	Interleukin-6
TNF-α	Tumor Necrosis Factor-alpha
IFN-γ	Interferon-gamma
PYY	Peptide YY
GLP-1	Glucagon-like peptide-1
NPCs	Neural progenitor cells
HDACs	Histone deacetylases
LTP/LTD	Long-term potentiation/Long-term depression
PSD-95	Postsynaptic density protein 95
NGF	Nerve growth factor
GLIN	Glial cell lineage-derived neurotrophic factor
JAK/STAT	Janus Kinase/Signal Transducer and Activator of Transcription
NMDA	N-Methyl-D-Aspartate
CUMS	Chronic unpredictable mild stress
NMDAR2B	N–methyl–D–aspartate Receptor 2B
NMDAR1	N–methyl–D–aspartate Receptor 1
NMDA2A	N–methyl–D–aspartate Receptor 2A
mRNA	messenger RNA
GAD	Glutamate decarboxylase
5-HT1A	5-Hydroxytryptamine 1A receptor
DRD1	Dopamine receptor D1
ADRA-2A	Alpha-2A adrenergic receptor
NR3C2	Mineralocorticoid receptor
CNR1	Cannabinoid receptor type 1
Adrb3	β3-adrenergic receptor
Avpr1a	Vasopressin 1a receptor
Drd5	Dopamine Receptor D5
Htr2b	5-hydroxytryptamine receptor 2B
SERT	5-HT transporter
SSRIs	Selective serotonin reuptake inhibitors
THP-1	Human monocytic leukemia cell line
IBS	Irritable bowel syndrome
miRNAs	microRNAs
NPY	Neuropeptide Y
RCTs	Randomized controlled trials
CSF	Cerebrospinal fluid
n-3 PUFA	Omega-3 polyunsaturated fatty acids
EPA	Eicosapentaenoic acid
DHA	Docosahexaenoic acid
VEGF-A	Vascular endothelial growth factor-A
DCX	Doublecortin
GABAA/B	Gamma-aminobutyric acid receptor types A and B
PI3K/Akt	Phosphoinositide 3-kinase/protein kinase B
RCT	Randomized controlled trial
OB	Oral probiotic
iPSC	Induced pluripotent stem cells
FMT	Fecal microbiota transplantation