AN	adult neurogenesis
BBB	blood brain barrier
BDNF	brain-derived neurotrophic factor
BrdU	bromo-2-deoxyuridine
CREB	cAMP response element-binding protein
GBA	gut-brain axis
GVD	gut-vascular barrier
CNS	central nervous system
GF	germ-free
HPA	hypothalamic–pituitary–adrenal axis
IGF	insulin-like growth factor
IL	interleukin
NPCs	neural progenitor cells
NSCs	neural stem cells
LJ	Lactobacillus johnsonii CJLJ103
PUFAs	Polyunsaturated fatty acids
ROS	reactive oxygen species
SEZ	subependymal zone
SCFAs	short-chain fatty acids
TNFα	tumor necrosis factor-α
TLR2	toll-like receptor