Monoamine neurotransmitters are derived from amino acids and include the catecholamines dopamine, noradrenaline and adrenaline, as well as serotonin. Noradrenaline is synthesised from tyrosine and plays a key role in sympathetic nervous system activity.

During sympathetic activation, noradrenaline is released from postganglionic neurones and acts on adrenergic receptors to produce effects such as tachycardia, sweating and increased alertness.

Exam rule: Monoamines → derived from amino acids, e.g. noradrenaline dopamine serotonin

Why not the other options?

Endomorphins: Neuropeptides that act as endogenous opioids, not monoamines.
 

GABA: An inhibitory neurotransmitter derived from glutamate, not a monoamine.
 

Acetylcholine: A separate neurotransmitter class synthesised from choline and acetyl-CoA.
 

Glutamate: An excitatory amino acid neurotransmitter, not a monoamine.