Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.14.16.2 (tyrosine hydroxylase)
14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure was devised to determine whether in the stimulated chromaffin cell phosphate is incorporated into specific proteins ("chromobindins") that bind to chromaffin granule membranes in a Ca2+-dependent manner. Cells were preincubated with 32P-labeled orthophosphate, then challenged with secretory stimuli. A postmicrosomal supernatant fraction was prepared from the cells and incubated with unlabeled chromaffin granule membranes in the presence of 5 mM Ca2+. Proteins that bound to the membranes were isolated by centrifugation and examined for 32P content by electrophoresis and autoradiography. Stimulation by carbamylcholine, nicotine, 56 mM K+, or 2 mM Ba2+ led to the incorporation of 32P into a 37-kDa protein that had previously been characterized as a substrate for protein kinase C in vitro (chromobindin 9, or CB9; Summers, T. A., and Creutz, C. E. (1985) J. Biol. Chem. 260, 2437-2443). Incorporation of 32P into this protein was dependent on extracellular Ca2+ and followed a time course that paralleled secretion of catecholamines, returning to base-line levels after 30 min, when secretion terminated. 32P was also incorporated into a 58-kDa protein that may be tyrosine hydroxylase and into an unidentified 28-kDa protein in response to cell stimulation, but neither of these proteins bound to granule membranes in a Ca2+-dependent manner. Treatment of cells with phorbol 12,13-dibutyrate, an activator of protein kinase C, led to 32P incorporation into the 37-kDa protein that was only 30% of the level obtained with nicotinic stimulation, suggesting that additional kinases may be involved in phosphorylating this protein in the stimulated cell.
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PMID:Phosphorylation of a chromaffin granule-binding protein in stimulated chromaffin cells. 370 Apr 8

The ability of neuronal depolarization to increase catecholamine biosynthesis in the poststimulation period was investigated in a preparation of central noradrenergic tissue, maintained in vitro. Rat hippocampal slices were superfused with oxygenated Krebs-Ringer phosphate saline (KRP) or depolarized with KRP containing 55 mM KCl. Slices were then transferred to fresh, nondepolarizing KRP containing [3H]tyrosine for further incubation. Ten minutes of K+ depolarization resulted in a 78% increase in [3H]catecholamine synthesis, measured in the poststimulation period, relative to nondepolarized, control slices. This activation of catecholamine synthesis was maintained for up to 10 min following termination of K+ depolarization. Depolarization in the presence of tetrodotoxin did not block the poststimulation increase in catecholamine synthesis. The increased catecholamine synthesis in the poststimulation period can be accounted for by increased tyrosine hydroxylation since: 1) the synthesis of [14C]catecholamines from [14C]dopa was not increased by K+ depolarization and 2) K+ depolarization led to a 71% increase in the accumulation of [3H]dopa newly synthesized from [3H]tyrosine in the presence of the decarboxylase inhibitor, brocresine. Under these conditions, no significant depletion of tissue norepinephrine could be detected. The depolarization-induced increase in catecholamine synthesis was independent of the presence of Ca++ in the superfusion and/or incubation media, suggesting its dissociation from Ca++-dependent transmitter release. The absence of enhanced [3H]catecholamine synthesis following depolarization of slices in a Ca++-free K+-KRP containing 1.0 mM ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) suggested that there is an absolute requirement for tissue Ca++ during the stimulation-induced synthesis activation process. There appears to be a depolarization-related phenomenon whose triggering is Ca++-independent, but which, in the presence of Ca++, is manifested as an increase in catecholamine biosynthesis (tyrosine hydroxylase activity).
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PMID:Poststimulation catecholamine synthesis and tyrosine hydroxylase activation in central noradrenergic neurons. II. Depolarized hippocampal slices. 610 44

A method was developed for the measurement of regional 2-deoxyglucose (2-DG) retention in rat brain by injecting tracer quantities of tritated 2-DG intravenously, dissecting out individual brain regions, making extracts of the tissue, and counting aliquots of the extracts. This technique permits the separation of unreacted 2-DG from 2-deoxyglucose-6-phosphate (2-DGP) by ion exchange chromatography as well as the performance of other biochemical measurements on the extracts. Using this method, the effect of unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra on 2-DG retention and 2-DGP formation by the striatum and the cerebral cortex was investigated. Animals were studied both 3 days and 2--4 weeks after lesioning. The location and efficacy of the lesions were verified histologically, behaviorally (by observing rotational behavior), and biochemically (by assay of striatal dopamine concentration or tyrosine hydroxylase activity). The lesions induced a mean asymmetry of less than 10% in 2-DG retention and in 2-DGP formation in striatum and cerebral cortex. This result was verified by [14C]2-DG autoradiography. Systemic administration of amphetamine (5 mg/kg) or apomorphine HBr (1.5 mg/kg) elicited rotational behavior, but did not induce a marked asymmetry of 2-DG retention in the regions studied. It is concluded that unilateral lesions of the nigrostriatal dopaminergic pathway have, at most, a modest effect on 2-DG retention by forebrain structures. We also conclude that vehicle injections may produce morphological and chemical evidence of brain injury, including small but reproducible changes in deoxyglucose retention.
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PMID:Effects of substantia nigra lesions on forebrain 2-deoxyglucose retention in the rat. 610 86

Data demonstrating the direct phosphorylation of tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] purified from rat pheochromocytoma by ATP, Mg2+ and cyclic AMP-dependent protein kinase catalytic subunit are presented. The incorporation of phosphate is highly correlated with the activation of the hydroxylase when either the time of preincubation or the amount of protein kinase subunit is varied. The rate of phosphorylation of tyrosine hydroylase compares favorably with that of H1 histone, a known substrate of protein kinase. Lineweaver-Burk analysis of crude or purified rat pheochromocytoma tyrosine hydroxylase activity, as a function of pterin cofactor concentration, in the absence of ATP, Mg2+, and protein kinase catalytic subunit, yields a curvilinear relationship which can be resolved into two lines, suggesting two enzyme forms with different affinities for pterin cofactor. A fraction of the hydroxylase present in the tumor exists in the activated state, presumably due to the presence of ATP and endogenous protein kinase activity. When the solubl enzyme is activated by cyclic AMP, ATP, Mg2+, and protein kinase, virtually all of the enzyme is converted to the low Km state. We conclude that tyrosine hydroxylase is a substrate of cyclic AMP-dependent protein kinase in vitro and, presumably, in vivo.
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PMID:Tyrosine hydroxylase: a substrate of cyclic AMP-dependent protein kinase. 610 82

Administration of 6-hydroxydopamine to adult rats results in changes in the superior cervical ganglion similar to those noted after axotomy; namely, a decrease in muscarinic receptor binding and increases in activities of the oxidative enzymes of the pentose phosphate pathway. These changes were either prevented or attenuated markedly by the systemic administration of nerve growth factor. Administration of nerve growth factor alone did not significantly increase N-methylscopolamine binding in the ganglion or reduce the activities of the oxidative enzymes. Explants of the ganglion maintained in serum-free medium over a period of 3 days demonstrated increases in oxidative enzyme activity and a decrease in N-methylscopolamine binding. Addition of 20 nM nerve growth factor to the culture medium prevented the decline in N-methylscopolamine binding in ganglion explants. The increases in oxidative enzyme activities were unaltered. Addition of high amounts of nerve growth factor, 200 nM, resulted in a significant increase in tyrosine hydroxylase activity but no further increase in N-methylscopolamine binding in ganglion explants. Glucocorticoids added to the culture medium did not affect the muscarinic binding or enzyme activities. Thus, decreases in muscarinic binding activity which occur in the superior cervical ganglion after axotomy or 6-hydroxydopamine treatment may be explained by a loss of nerve growth factor supplied to the ganglion. Increases in the oxidative enzymes of the pentose phosphate pathway that occur in the ganglion after axonal injury appear to involve additional factors.
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PMID:Muscarinic receptor binding and oxidative enzyme activities in the adult rat superior cervical ganglion: effects of 6-hydroxydopamine and nerve growth factor. 613 21

The ideal methodologies for the localization of tyrosine hydroxylase-like immunoreactivity were investigated using the quantitative capabilities of the Leitz MPV-3 microspectrofluorometer to determine the best protocol. The following method was found to give the best results. The animals were perfused with the two-stage procedure [1] consisting of an initial perfusion with 4% paraformaldehyde at pH 6.5 and a second perfusion of 4% paraformaldehyde at pH 11. The brains were sectioned on a cryostat and the loose sections were placed in the primary antibody for 80 hours (the time of saturation of the reaction). The primary antibody solution contained 0.1-0.5% lambda-carregeenan and 0.3% Triton-X 100 in phosphate buffered saline. The sections were rinsed and placed in a 0.1-0.3% carregeenan solution with 0.1% Triton-X 100 and containing the secondary antibody. The sections were mounted onto chrome alum subbed slides and allowed to dry. The sections were coverslipped with buffered glycerine (pH 8.6) containing 2 mg/ml paraphenylene diamine as a mounting medium. This medium provided excellent protection from fading but certain subsequent enzyme staining (notably acetylcholinesterase) required the use of buffered glycerine alone. Various counterstains were evaluated for their compatability with the FITC fluorescence. A detailed methodology is presented.
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PMID:The localization of tyrosine hydroxylase-like immunoreactivity in the central nervous system: methodological considerations. 614 32

Chronic denervation of the heart leads to depletion of tissue catecholamines, giving rise to metabolic abnormalities, including a reduction in cardiac glucose oxidation. Impaired glucose oxidation could cause an increased oxidation of fat, which in turn could lead to development of coronary artery disease. Cardiac glucose oxidation (using 14C-(U),D-glucose) was studied in female baboons, before, and three to five weeks after, autotransplantation. Systemic arterial and coronary sinus samples were analyzed for total CO2 content, O2 content, 14CO2, glucose, lactate, pH, PCO2, and PO2. Tissue for metabolite assays (adenosine-5'-triphosphate [ADP] and creatine phosphate [CP]; glucose-6-phosphate [G6P] and fructose 6-phosphate [F6P] was obtained from the right ventricle before and after autotransplantation in some animals. There were no significant changes. Tissue was also obtained postmortem for analysis of noradrenaline, soluble tyrosine hydroxylase activity, and contractile and regulatory proteins. There was a large decrease in tissue noradrenaline, suggesting almost total sympathetic denervation. The level of tyrosine hydroxylase activity shows that the denervated heart can synthesize dopamine. There were no detectable changes in the contractile or regulatory proteins. In six of the nine baboons successfully studied, there was a distinct decrease in the oxidation of glucose after autotransplantation (P less than 0.05). This indicates that the removal of the sympathetic and parasympathetic nerve supply to the heart affects the ratio of glucose oxidized to other substrates.
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PMID:Metabolic changes in the autotransplanted baboon heart. 614 39

Nitric oxide synthase-like immunoreactivity was found in a subpopulation of sympathetic postganglionic neurons in the cat stellate and lower lumbar ganglia. In the ganglia of other segments such cells were rare. Double staining for tyrosine hydroxylase-like immunoreactivity and nitric oxide synthase-like immunoreactivity or the reduced nicotinamide adenine dinucleotide phosphate diaphorase reaction indicated that nitric oxide synthase-like immunoreactivity and reduced nicotinamide adenine dinucleotide phosphate diaphorase reactivity was always co-localized and was confined to tyrosine hydroxylase-negative (presumably cholinergic) ganglion cells, and was present in most of them. The occurrence of nitric oxide synthase in two subpopulations of cholinergic postganglionic neurons was investigated in triple staining experiments. Presumptive sudomotor neurons have been previously defined as scattered cells containing calcitonin gene-related peptide-like immunoreactivity, usually accompanied by vasoactive intestinal peptide-like immunoreactivity: 99% of these contained nitric oxide synthase. Presumptive muscle vasodilator neurons have been previously identified as clumped cells with strong vasoactive intestinal peptide-like immunoreactivity but no calcitonin gene-related peptide-like immunoreactivity: 70% of these contained nitric oxide synthase. Sweat glands were found in the paw pad skin surrounded by varicose fibres showing calcitonin gene-related peptide-like immunoreactivity and vasoactive intestinal peptide-like immunoreactivity, confirming previous work. Such fibres also stained for nitric oxide synthase-like immunoreactivity and reduced nicotinamide adenine dinucleotide phosphate diaphorase reactivity, although their staining was relatively weaker than in the corresponding cell bodies. Varicose fibres with the same chemical coding were also found around all large and most medium and small arteries in the paw skin as well as around arteriovenous anastomoses. Fibres with the muscle vasodilator coding (vasoactive intestinal peptide-like immunoreactivity without calcitonin gene-related peptide-like immunoreactivity) were not seen in paw skin. These results suggest that nitric oxide may act as a co-transmitter (with acetylcholine, substance P, vasoactive intestinal peptide and calcitonin gene-related peptide) in sudomotor neurons and (with acetylcholine and vasoactive intestinal peptide) in vasodilator neurons. Collateral branches of sudomotor neurons may innervate skin vessels, and release vasodilator transmitters including nitric oxide to cause the vasodilatation which provides the fluid supply for sweat formation. Alternatively, separate vasodilator neurons to skin may share the same chemical code as sudomotor neurons.
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PMID:Nitric oxide synthase and chemical coding in cat sympathetic postganglionic neurons. 747 30

Nitric oxide (NO) is synthesized in neurons and is a potent relaxor of vascular and nonvascular smooth muscle. The uterus contains abundant NO-synthesizing nerves which could be autonomic and/or sensory. This study was undertaken to determine: 1) the source(s) of NO-synthesizing nerves in the rat uterus and 2) what other neuropeptides or transmitter markers might coexist with NO in these nerves. Retrograde axonal tracing, utilizing Fluorogold injected into the uterine cervix, was employed for identifying sources of uterine-projecting neurons. NO-synthesizing nerves were visualized by staining for nicotinamide adenine dinucleotide phosphate (reduced)-diaphorase (NADPH-d) and immunostaining with an antibody against neuronal/type I NO synthase (NOS). NADPH-d-positive perikarya and terminal fibers were NOS-immunoreactive (-I). Some NOS-I/NADPH-d-positive nerves in the uterus are parasympathetic and originate from neurons in the pelvic paracervical ganglia (PG) and some are sensory and originate from neurons in thoracic, lumbar, and sacral dorsal root ganglia. No evidence for NOS-I/NADPH-d-positive sympathetic nerves in the uterus was obtained. Furthermore, double immunostaining revealed that in parasympathetic neurons, NOS-I/NADPH-d-reactivity coexists with vasoactive intestinal polypeptide, neuropeptide Y, and acetylcholinesterase and in sensory nerves, NOS-I/NADPH-d-reactivity coexists with calcitonin gene-related peptide and substance P. In addition, tyrosine hydroxylase(TH)-I neurons of the PG do not contain NOS-I/NADPH-d-reactivity, but some TH-I neurons are apposed by NOS-I varicosities. These results suggest NO-synthesizing nerves in the uterus are autonomic and sensory, and could play significant roles, possibly in conjunction with other putative transmitter agents, in the control of uterine myometrium and vasculature.
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PMID:Nitric oxide nerves in the uterus are parasympathetic, sensory, and contain neuropeptides. 753 54

Spleens from representatives of the three amphibian orders were examined using sucrose-potassium phosphate-glyoxylic acid (SPG) histofluorescence to detect catecholamines and immunocytochemistry to detect several neural antigens. Nerve fibers are scattered throughout the spleens of adult salamanders (Taricha torosa, Notophthalmus viridescens, and Ambystoma mexicanum). A less abundant but similarly diffuse pattern of innervation characterizes the spleen of the caecilian, Typhlonectes sp. The spleen of the adult frog, Xenopus laevis, is separated into clearly defined compartments of red pulp and white pulp, much as is seen in the mammalian spleen. As in mammals, sympathetic innervation of the Xenopus spleen is noradrenergic (NA) and confined to the white pulp. The white pulp of Xenopus spleen also contains fibers which stain for neuropeptide Y and substance P. The spleen of the anuran, Rana pipiens, is also highly compartmentalized, with tyrosine hydroxylase positive fibers in proximity to blood vessels. These findings provide an anatomical substrate for neural-immune interactions in the Amphibia.
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PMID:Noradrenergic and peptidergic innervation of the amphibian spleen: comparative studies. 753 85


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