Monoamines I

Outline of Lecture 08 (02-20 A; Baraban) Monoamines I I. There are three basic criteria for proving a substance is a nxt 1) Sufficient: substance mimics endogenous response 2) Necessary: receptor antagonist block response due to substance 3) Presence: substance is the endogenous agent (e.g. can be isolated/purified) Acetylcholine Norepinephrine Autonomic Parasympathetic Sympathetic nervous system Biochemical Multistep: Acetyl CoA + Choline  ACh synthesis Catalyzed by choline acetyltransferase Tyr  DOPA  Dopamine  NE (NE  Epi, in adrenal medulla) Vesicular • High affinity choline uptake into presyn. Vesicular dopamine transporter (therefore entrapment • ACh synthesis in cytoplasm NE synthesis occurs within vesicle) • Vesicular ACh transporter Inactivation ACh  Acetic acid + choline High affinity NE uptake Catalyzed by ACh-esterase (AChE) Pharmacology • Muscarine: muscarinic receptor agonist • Cocaine: blocks NE uptake, tachycardia • Atropine: muscarinic receptor antagonist, reverses bradycardia • Nerve gas: irreversible inhibitor of AChE •