NEUR 3200 Lecture Notes - Lecture 6: Aromatic L-Amino Acid Decarboxylase, Tyrosine Hydroxylase, Knockout Mouse
31 Oct 2017
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Document Summary
Catecholamine synthesis begins with the amino acid tyrosine (precursor). Tyrosine hydroxylase (th) and aromatic amino acid decarboxylase (aadc) are found in neurons that make da: these are enzymes. Neurons that synthesize ne also have dopamine (cid:533)-hydroxylase (dbh). Th is the rate-limiting enzyme in the pathway. It determines the overall rate of da or ne synthesis: determines how much da/ne is generated. Tyrosine is not an essential amino acid. After synthesis, catecholamines are packaged into vesicles. A specific transporter in the vesicle membrane recognizes monoamines the vesicular monoamine transporter (vmat). Vmat can be blocked by the drug reserpine. Catecholamines are normally released by exocytosis when a nerve impulse reaches the terminal. Some drugs (example: amphetamine) can stimulate da release at the synapse: promote additional binding, ap promotes release. Reuptake: da and ne move from the synaptic cleft into the nerve terminal via specific membrane transporter proteins.
