title: Both nicotinic and muscarinic agonists acutely increase tyrosine 3-monooxygenase activity in the superior cervical ganglion.
abstract: The activity of tyrosine 3-monooxygenase in rat superior cervical ganglia in vitro was measured by monitoring their rate of dopa production. Cholinergic agonists produce a rapid and reversible increase in dopa synthesis in the ganglia. Carbachol (0.1 mM) causes a 5- to 6-fold increase in dopa synthesis. The action of carbachol is largely inhibited by the nicotinic antagonist hexamethonium (3 mM) and is completely blocked by a combination of hexamethonium and the muscarinic antagonist atropine (6 microM). Dimethylphenylpiperazinium (1 mM), a specific nicotinic agonist, produces a 4-fold increase in dopa synthesis. The action of dimethylphenylpiperazinium is blocked by hexamethonium but not by atropine. Bethanechol (1 mM), a muscarinic agonist, causes a 2-fold increase in dopa synthesis. The action of bethanechol is inhibited by atropine but not by hexamethonium. It is concluded that tyrosine 3-monooxygenase activity in rat superior cervical ganglia can be increased by both nicotinic and muscarinic stimulation, that nicotinic stimulation can produce a greater increase than can muscarinic stimulation and that carbachol increases enzyme activity by a combination of both pathways. These cholinergic mechanisms for the acute regulation of tyrosine 3-monooxygenase may be activated in vivo by acetylcholine released from preganglionic neurons and thus may play a role in the physiological regulation of catecholamine synthesis in sympathetic ganglia.
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001626:Bethanechol Compounds / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D005728:Ganglia, Sympathetic / Q000201:enzymology*; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D009116:Muscarine / Q000037:antagonists & inhibitors*; D009538:Nicotine / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D001626:Bethanechol Compounds; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D004295:Dihydroxyphenylalanine; D009538:Nicotine; D001285:Atropine; D009116:Muscarine; D002217:Carbachol; D014446:Tyrosine 3-Monooxygenase