3-MT	3-methoxytyramine
5-HIAA	5-hydroxyindoleacetic acid
CNS	the central nervous system
COMT	catechol-O-methyltransferase
DAT	dopamine transporter
DOPAC	3,4-dihydroxyphenylacetic acid
DPP-4 enzyme	the dipeptidyl peptidase-4 enzyme
FSCV	fast-scan cyclic voltammetry
GLP-1	the glucagon-like peptide-1
HVA	homovanillic acid
i.p.	intraperitoneally
HPLC-ED	high-performance liquid chromatography with electrochemical detection
NA	noradrenaline
NMDA	N-methyl-D-aspartate
NMN	normetanephrine
RQ-PCR	real-time quantitative reverse transcription polymerase chain reaction
SD	standard deviation
SEM	standard error of the mean
Ser	serotonin
VMAT2	vesicular monoamine transporter 2
VTA	ventral tegmental area