5-HT	serotonin
5-HTRs	serotonin receptors
aa	amino acids
AA	arachidonic acid
AADE	arachidonic acid-derived eicosanoids
AC	adenylyl cyclase
ACh	acetylcholine
AD	Alzheimer’s disease
ADHD	attention-deficit/hyperactivity disorder
AP-1	activator protein 1
APCs	antigen-presenting cells
ARRB2	arrestin beta-2, also known as beta-arrestin-2
ASD	autism spectrum disorders
BBB	blood–brain barrier
bFGF	basic fibroblast growth factor
cAMP	cyclic 3′,5′ adenosine monophosphate
CBM	CBM signalosome complex = CARD11 (the caspase recruitment domain family member 11)—BCL10 (B cell CLL/lymphoma 10)—MALT1 (mucosa associated lymphoid tissue lymphoma translocation protein 1) paracaspase
c-fos	protooncogene (human homolog of the retroviral oncogene v-fos)
cGMP	cyclic guanosine monophosphate
CNS	central nervous system
CREB	cAMP-responsive element-binding protein
CSF	cerebrospinal fluid
DA	dopamine
DAG	diacylglycerol
DAO	diamine oxidase
DCs	dendritic cells
ECL cells	enterochromaffin-like cells
ECs	endothelial cells
eNOS	endothelial nitric oxide synthase
ERS	endoplasmic reticulum stress
GABA	γ-amino butyric acid
GDP	guanosine diphosphate
GLU	glutamate
GTP	guanosine triphosphate
GPCRs	G protein-coupled receptors, also known as the seven-(pass)-transmembrane (7TM) domain receptors
H1R, H2R, H3R, H4R	four histamine receptors, respectively
HA	histamine
HD	Huntington’s disease
HDC	enzyme L-histidine decarboxylase
HMT	histamine N-methyltransferase, also known as HNMT
IAA	imidazole acetic acid
IAA-RP	imidazole acetic acid ribotide
ID	intellectual disability
IFG	inferior frontal gyrus
IFN-γ	interferon gamma
IL-1β, IL-10, IL-12, IL-33	interleukins: 1 beta, 10, 12, and 33, respectively
IP3	inositol 1,4,5-trisphosphate
KD	dissociation constant
LBs	Lewy bodies
MAO-B	monoamine oxidase B
MAPK	mitogen-activated protein kinase
MCH	melanin-concentrating hormone
MCs	mast cells
MDD	major depressive disorder
NA	norepinephrine
NMD	neurodevelopmental motor disorders
NSCs	neural stem cells
NSD	narcolepsy spectrum disorder
NF-κβ	nuclear factor kappa-light-chain-enhancer of activated B cells
NK cells	natural killer cells
NMDA	N-methyl-D-aspartate
NO	nitric oxide
NREM	non-rapid eye movement phase of sleep
Nτ-MH	tele-methylhistamine
OCPD	obsessive–compulsive personality disorder
OCT3	organic cation transporter 3
PD	Parkinson’s disease
PFC	prefrontal cortex
PIP2	phosphatidylinositol 4,5-bisphosphate
PKA	protein kinase A
PKC	protein kinase C
PLA2	phospholipase A2
PLC	phospholipase C
PLD	phospholipase D
PMAT	plasma membrane monoamine transporter
REM	rapid eye movement phase of sleep
ROS	reactive oxygen species
Schiz	schizophrenia
SDAT	senile dementia of the Alzheimer’s disease type
SNP	single-nucleotide polymorphism
TGFβ	transforming growth factor beta
Th1, Th2	Type 1 T helper and type 2 T helper cells, respectively
t-MIAA	tele-methylimidazole acetic acid
TMN	tuberomammillary nucleus
TNFα	tumor necrosis factor alpha
TRAF6	tumor necrosis factor (TNF) receptor-associated factor 6
VEGF	vascular endothelial growth factor
VMAT2	vesicular monoamine transporter
VSMCs	vascular smooth muscle cells
XO	xanthine oxidase