Stimulant
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![A chart comparing the chemical structures of different amphetamine derivatives](/Images/godic/202502/02/Methamphetamines0339.PNG")
![Human biosynthesis pathway for trace amines and catecholamines[19][20]
L-Phenylalanine
L-Tyrosine
L-Dopa
Epinephrine
Phenethylamine
p-Tyramine
Dopamine
Norepinephrine
N-Methylphenethylamine
N-Methyltyramine
p-Octopamine
Synephrine
3-Methoxytyramine
AADC
AADC
AADC
PNMT
PNMT
PNMT
PNMT
AAAH
AAAH
COMT
DBH
DBH
This is the biosynthesis of catecholamines, including dopamine, as well as phenethylaminergic trace amines from the amino acid phenylalanine. Trace amines are endogenous agonists of TAAR1, the same receptor activated by amphetamine;[14] consequently, all of these trace amines are stimulants. Abbreviations: DBH, dopamine β-hydroxylase; AADC, aromatic L-amino acid decarboxylase; AAAH, aromatic amino acid hydroxylase; COMT, catechol O-methyltransferase; PNMT, phenylethanolamine N-methyltransferase](/Images/godic/202502/02/Catecholamine_and_trace_amine_biosynthesis0339.png")
![Roasted coffee beans, a common source of caffeine.](/Images/godic/202502/02/Roasted_coffee_beans0339.jpg")
Stimulants (also referred to as psychostimulants) are psychoactive drugs that induce temporary improvements in either mental or physical functions or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others. Due to their rendering a characteristic "up" feeling, stimulants are also occasionally referred to as "uppers". Depressants or "downers", which decrease mental and/or physical function, are in stark contrast to stimulants and are considered to be the functionally opposite drug class. Stimulants are widely used throughout the world as prescription medicines and without prescription both as legal substances and illicit substances of recreational use or abuse.