MDD	Major depressive disorder
US	Ultrasound stress
BDNF	Brain-derived neurotrophic factor
TrkB	Tropomyosin receptor kinase B
TrkB-FL	Full-length tropomyosin receptor kinase B
TrkB-T	Truncated tropomyosin receptor kinase B
IL	Interleukin
DSM-5	Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition
SSD	Somatic symptom disorder
HPA	Hypothalamic–pituitary–adrenal
NMDA	N-methyl-D-aspartate receptor
CORT	Corticosterone
PSD95	Postsynaptic density protein 95
PSA-NCAM	Polysialylated neural cell adhesion molecule
TNF	Tumor necrosis factor
MyD88	Myeloid differentiation primary response 88
NF-κB	Nuclear factor kappa B
MAPK	Mitogen-activated protein kinase
RNA	Ribonucleic acid
mRNA	Messenger ribonucleic acid
i.c.v.	Intracerebroventricular
ANOVA	Analysis of variance
SEM	Standard error of the mean
RIT	Resident–intruder test
SI	Social interaction
ARRIVE	Animal Research: Reporting of In Vivo Experiments
RT-qPCR	Reverse transcription quantitative polymerase chain reaction
ELISA	Enzyme-linked immunosorbent assay
cDNA	Complementary DNA
GAPDH	Glyceraldehyde-3-phosphate dehydrogenase