Acetylcholine is the neurotransmitter used at the neuromuscular junction —in other words, it is the chemical that motor neurons of the nervous system release in order to activate muscles.This property means that drugs that affect cholinergic systems can have very dangerous effects ranging from paralysis to convulsions.heir effect on target cells is usually inhibitory. Muscarinic acetylcholine receptors are found in both the central nervous system and the peripheral nervous system of the heart, lungs, upper gastrointestinal tract, and sweat glands.