Acetylcholine receptors

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Acetylcholine receptors (also shortened to cholinoceptors) are transmembrane receptors in various areas of the nervous system that bind the neurotransmitter acetylcholine (ACh) as a substrate.

There are two types of ACh receptors, nicotinic acetylcholine receptors (nAChR) and muscarinic acetylcholine receptors (mAChR).

acetylcholine receptors (nicotinic) heteropentamer, Torpedo marmorata.

Nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors are ionotropic, i.e. they are themselves ion channels (first messengers). Their effect is mostly excitatory. They can be activated by nicotine or indirectly by physostigmine (acetylcholinesterase inhibitor) by increasing the acetylcholine concentration in the synaptic cleft and are therefore called n-acetylcholine receptors. The antagonist is curare (ACh inhibitor).

A distinction is made between the following subtypes:

  • n1 (motor end plate)
  • n2 (neuronal, preganglionic to postganglionic)

Muscarinic acetylcholine receptors

Muscarinic acetylcholine receptors are metabotropic, i.e. G-protein coupled. They can be activated by muscarin (alkaloid from the fly agaric; agonist), which is why they are also called m-acetylcholine receptors. They are inhibited by atropine and other ACh inhibitors and antagonists.

A distinction is made between the following subtypes

  • m1,m3,m5: Effect via GqIP3/DAG cascade
  • m2,m4: effect overGi; reduction of cAMP


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