Acetylcholine: nicotinic, muscarinic and AChE

The first transmitter discovered — and a clear example of one messenger with a fast receptor and a slow one.

Where this fitsConnects to 1 · Unlocks 1

Connects to: Fast doors and slow keypads: ionotropic and metabotropic receptors — Nicotinic = ionotropic; muscarinic = metabotropic.
Unlocks: Other messengers: histamine, opioids, hormones and more — Anticholinergic side effects (e.g., diphenhydramine) come from blocking muscarinic receptors.

Orient

Acetylcholine (ACh) – made from acetyl coenzyme A + choline (from diet/recycled) and broken down by AChE. Two major receptor types: nicotinic – binding site for nicotine (ionotropic) – and muscarinic – binding site for muscarine (metabotropic). Muscarinic receptors drive parasympathetic nervous system activation, “rest and digest”: SLUDGEM.

Course terms

Your professor's wording, word for word from the slides. Learn the term and this definition — the explanation underneath is only there to help it make sense.

Acetylcholine synthesis: “Acetyl coenzyme A + choline (from diet/recycled)”Slides 03, p. 17
AChE breaks ACh down; AChE inhibitors can be irreversible (pesticides, nerve gases such as sarin) or reversible (nootropics, Alzheimer's medications).
Nicotinic receptor: “Nicotinic – binding site for nicotine”Slides 03, p. 18
Ionotropic; muscle contraction and cognitive processes (learning, memory, attention).
Muscarinic receptor: “Muscarinic – binding site for muscarine (an active chemical in Amanita muscaria mushroom)”Slides 03, p. 18
Metabotropic; M1, M3, M5 excitatory, M2, M4 inhibitory.
Parasympathetic nervous system: ““rest and digest”, “feed and breed””Slides 03, p. 19
Muscarinic receptors drive parasympathetic activation.
SLUDGEM: “Salivation Lacrimation (tear production) Urination Diaphoresis (sweat production) Gastrointestinal effects Emesis (vomiting) Miosis (pupil constriction)”Slides 03, p. 19
The course mnemonic (“Musky Sludge”) for muscarinic/parasympathetic effects.

From your course: Course slides 03, pp. 17–20

Tip: the ← and → keys move through the lesson.

Full lesson: Precursors and acetylcholine