Question

endorphins are
neuropeptides.
cholinergic.
adrenergic.
monoamines.

Explanation:

Endorphins are neuropeptides produced by the body that act as natural pain - relievers and mood - elevators. They are not cholinergic (related to acetylcholine), adrenergic (related to adrenaline - like substances), or monoamines (a class of neurotransmitters like dopamine, serotonin).

Answer:

neuropeptides.