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Updated: Aug 4, 2026

Comprehensive Profiling of Dopamine Regulation in Substantia Nigra and Ventral Tegmental Area
Published on: August 10, 2012
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.
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