Saturday, August 29, 2009

CATACHOLAMINE SYNTHESIS

Catecholamine Synthetic Pathway

Adrenergic Neurotransmission: Introduction to the Neurotransmitters

Norepinephrine: transmitter released at most postganglionic sympathetic terminals

Dopamine: major CNS neurotransmitter of mammalian extrapyramidal system and some mesocortical and mesolimbic neurononal pathways.
Epinephrine: most important hormone of the adrenal medulla
Catecholamine Synthesis, Storage, and Release

Aromatic L-amino acid decarboxylase (DOPA decarboxylase)

dopa leads to dopamine
methyldopa leads to a-methyldopamine (converted by dopamine ß hydroxylase to the "false transmitter" alpha-norepinephrine)
5-hydroxy-L-tryptophanleads to5-hydroxytryptamine (5-HT)
Tyrosine Hydroxylase
tyrosine leads to DOPA
rate limiting step in pathway
tyrosine hydroxylase is a substrate for cAMP-dependent and Ca2+ - calmodulin-sensitive protein kinase and protein kinase C
Increased hydroxylase activity is associated with the phosphorylated enzyme

No comments: