title: Brain tyrosine hydroxylase: kinetic properties and regulation of the activity.
abstract: Electrical stimulation of rat hypothalamic synaptosome suspensions produced activation of tyrosine hydroxylase due to increase of the affinity for tyrosine and 6,7-dimethyl-5,6,7,8-tetrahydropterine cofactor, decrease of the affinity for dopamine and enhancement of substrate inhibition. Cocaine (10(-7) - 10(-5) M) in vitro caused enzyme activation; when administered to animals systemically (0.5 mg/kg) the drug produced inhibition of hypothalamic tyrosine hydroxylase probably through a receptor-mediated feedback mechanism.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000502:physiology; D002395:Catecholamines / Q000096:biosynthesis; D003042:Cocaine / Q000494:pharmacology; D005246:Feedback; D007031:Hypothalamus / Q000201:enzymology / Q000502:physiology; D017981:Receptors, Neurotransmitter; D013574:Synaptosomes / Q000201:enzymology / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D002395:Catecholamines; D017981:Receptors, Neurotransmitter; D014446:Tyrosine 3-Monooxygenase; D003042:Cocaine