title: Modulatory role of catecholamines on tyrosine hydroxylase induction.
abstract: The possible modulatory role of cytoplasmic catecholamines on tyrosine hydroxylase induction was studied. Rat superior cervical ganglia were kept in organ culture and after 48 h tyrosine hydroxylase activity was determined. Exposure to 10(-4) M carbachol during 4 h almost doubled the control activity. Incubation with 10(-5) M noradrenaline or 10(-5) M dopamine impaired the carbachol-mediated induction of the enzyme. This effect was not blocked by 10(-7) M  propranolol, 2.4 X 10(-6) M haloperidol or 3.1 X 10(-6) M phentolamine. Inhibition of monoamine oxidase activity by 5.1 X 10(-4) M pargyline inhibited the effect of carbachol. When the pool of endogenous catecholamines was decreased by alpha-methyl-p-tyrosine, carbachol induced tyrosine hydroxylase to the same extent as in non-depleted ganglia. It is suggested that the long-term regulation of tyrosine hydroxylase is modulated by a strategic cytoplasmic pool of catecholamines.
mesh_terms: D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002395:Catecholamines / Q000502:physiology*; D004347:Drug Interactions; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D008781:Methyltyrosines / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
chemical_list: D002395:Catecholamines; D008781:Methyltyrosines; D002217:Carbachol; D010293:Pargyline; D014446:Tyrosine 3-Monooxygenase; D009638:Norepinephrine