Acetylcholine receptors

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

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

Acetylcholine receptors (nicotinic) heteropentamer, Torpedo marmorata.

Nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors are ionotropic , ie they are themselves ion channels (first messenger). Their effect is usually excitatory (arousing). 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:

  • n 1 (motorized end plate)
  • n 2 (neuronal, pre- to postganglionic)

Muscarinic acetylcholine receptors

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

A distinction is made between the following subtypes:

  • m 1 , m 3 , m 5 : effect via G q IP 3 / DAG cascade
  • m 2 , m 4 : effect via G i ; Lowering of cAMP


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