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)

In situ hybridization histochemistry and indirect immunofluorescence histochemistry were used to study changes in the expression of vasopressin (VP), oxytocin (OXY), tyrosine hydroxylase (TH), galanin (GAL), dynorphin (DYN) and cholecystokinin (CCK) in hypothalamic magnocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of rats. After prolonged administration of 2% sodium chloride as drinking water (salt-loading), the treatment increased the levels of VP, OXY, TH, GAL, DYN and CCK mRNA in the PVN and SON. The increase in CCK mRNA was, however, proportionally higher in the PVN than in the SON. Within cell bodies of the PVN and SON of salt-loaded rats, a depletion of VP- and OXY-like immunoreactivity (LI) and an increase in TH-LI were seen. In salt-loaded/colchicine-treated rats, a marked decrease in GAL- and DYN-LI, but no specific changes in CCK-LI were observed. Within nerve fibers of the posterior pituitary of salt-loaded rats, a marked depletion of VP-, GAL- and DYN-LI was found. Less pronounced depletion was observed in OXY- and CCK-LI, and no specific changes in TH-LI were seen. The results show that high plasma osmolality induces increased mRNA levels for VP, OXY, TH, GAL, DYN and CCK, presumably indicating increased synthesis, an increased export from cell somata of VP, OXY, GAL and DYN, and a decrease in levels of these peptides in the posterior pituitary, suggesting increased release. The catecholamine-synthesizing enzyme TH, however, which has a cytoplasmic localization and is not released from nerve endings, remains high in the cell bodies and nerve endings during this state of increased activity.
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PMID:Peptides and transmitter enzymes in hypothalamic magnocellular neurons after administration of hyperosmotic stimuli: comparison between messenger RNA and peptide/protein levels. 169 5

This study compared tyrosine hydroxylase (TH) mRNA signal levels, relative quantity of TH protein, and the catalytic activity of TH in the tuberoinfundibular dopaminergic neurons (TIDA) of male and ovariectomized (OVEX) female rats. In addition, the effects of monosodium glutamate (MSG) neurotoxicity on these parameters of TH regulation were evaluated. Neonatal rats were injected with MSG (4 mg/g body weight) or 10% sodium chloride (controls) on alternate days for the first 10 days of life. Females were ovariectomized on day 45 of age, and all rats were used between 60 and 80 days of age. The TH mRNA signal levels, as assessed by an in situ hybridization technique, were 2-fold higher in control females than in control males, whereas the number of TH mRNA-containing cells was similar between sexes. The TH immunostainings of the TIDA perikarya in the arcuate nucleus and of the nerve terminals in the median eminence were qualitatively more intense in females than males. The catalytic activity of TH, as determined by in vitro DOPA accumulation in the stalk-median eminence, was 3-fold greater in females than males. Neonatal MSG-treatment resulted in a marked reduction in the number of TH mRNA-containing cells and TH-immunopositive cells in the arcuate nucleus of both sexes, as well as a decrease in the intensity of TH immunostaining in the median eminence. The cellular mRNA signal levels for TH were markedly reduced in females after MSG treatment, but were unchanged in males. MSG treatment reduced TH activity to 20% of control levels in females, but did not alter enzyme activity in males.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sex-related alterations in hypothalamic tyrosine hydroxylase after neonatal monosodium glutamate treatment. 198 Jul 22

We examined by immunohistochemistry the effect of salt loading on the expression of tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), and GTP cyclohydrolase I (GCH) in Purkinje cells of the mouse cerebellum. In control mice, only a few Purkinje cells were positive for TH or AADC. No Purkinje cells were stained for GCH. Drinking 2% sodium chloride for 2 weeks resulted in an increase in the number of TH- or AADC-positive Purkinje cells in the caudal vermis, paraflocculus and flocculus of the cerebellum. In contrast, no Purkinje cells were immunoreactive to GCH or L-DOPA after the salt loading. The present findings suggest that the salt loading differentially affects the expression of TH, AADC and GCH in Purkinje cells of the mouse cerebellum.
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PMID:Enhanced expression of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in cerebellar Purkinje cells of mouse after hyperosmotic stimuli. 747

Islet beta cell adaptation to dexamethasone-induced insulin resistance was characterized with respect to glucose-stimulated insulin secretion and islet innervation. Male Sprague-Dawley rats were injected daily with dexamethasone (2 mg/kg for 12 days), which resulted in hyperinsulinemia and hyperglycemia compared with controls (which were injected with sodium chloride). Insulin secretion was characterized in collagenase-isolated islets. Islet innervation was examined by immunocytochemical analysis of tyrosine hydroxylase, neuropeptide Y (sympathetic nerves), and vasoactive intestinal polypeptide (cholinergic nerves). In islets isolated from the insulin-resistant animals, the insulin response to 3.3 or 8.3 mM glucose was three times greater during perifusion compared with controls (p < 0.001). Incubation of islets at 0 to 20 mM glucose revealed a marked leftward shift of the glucose dose-response relation after dexamethasone treatment (potency ratio, 1.78; p < 0.01), with no difference at 0 or 20 mM glucose. Thus, the potency but not the efficacy of glucose was increased. The number of islet nerves did not differ between dexamethasone-treated rats and controls. Dexamethasone-induced insulin resistance leads to adaptively increased glucose responsiveness of the islet beta cells, with increased potency, but not increased efficacy, of glucose to stimulate insulin secretion without any evidence of altered islet innervation.
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PMID:Beta cell adaptation to dexamethasone-induced insulin resistance in rats involves increased glucose responsiveness but not glucose effectiveness. 1124 69

The mammalian olfactory bulb (OB) is among the few regions in adult brain which generates interneurons. A subpopulation of these phenotypically diverse interneurons is dopaminergic (DA) periglomerular cells. Full phenotypic development as indicated by expression of tyrosine hydroxylase (TH), the first enzyme in DA biosynthesis, requires afferent activity or equivalent depolarizing conditions. To investigate the hypothesis that cFOS regulates TH expression, this study analyzed OB slice cultures obtained from neonatal transgenic mice expressing 9 kb of TH promoter directing expression of green fluorescent protein (TH/GFP). Cultures were depolarized with 50 mM potassium chloride (KCl), the calcium channel blocker, nifedipine (10 microM) with KCl, or an equimolar concentration of sodium chloride (NaCl). Depolarization increased cFOS expression 6-fold peaking at about 3 h. Staining decreased rapidly returning to control, NaCl, levels by 48 h post-stimulation when TH/GFP expression was highest. Nifedipine blocked the increase in TH and cFOS suggesting that similar signal transduction pathways mediate both responses.
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PMID:Temporal and spatial disparity in cFOS expression and dopamine phenotypic differentiation in the neonatal mouse olfactory bulb. 1694 18

In this study we try to simultaneously investigate the response of neurons and astrocytes of rats following hyperosmotic stimulation and test the possibility that the reciprocal pathways between medullary visceral zone (MVZ) and hypothalamic paraventricular nucleus (PVN) or supraoptic nucleus (SON). Hyperosmotic pressure animal model was established by administering 3% sodium chloride as drinking water to rats. The distribution and expression of the HRP retrogradely labeled neurons, Fos, tyrosine hydroxylase (TH) or vasopressin (VP) positive neuron and glial fibrillary acidic protein (GFAP) positive astrocytes in the MVZ, SON and PVN were observed by quadruplicate-labeling methods of WGA-HRP retrograde tracing combined with anti-Fos, TH (or VP) and GFAP immunohistochemical technique. Fos positive neurons within the MVZ, PVN and SON increased markedly. There were also a large number of GFAP positive structures in the brain and their distribution pattern was fundamentally similar or analogous to Fos positive neurons in the above-mentioned areas. The augmented GFAP reactivities took on hypertrophic cell bodies, thicker and longer processes. Quadruplicate immunohistochemical staining showed that a neuron could be closely surrounded by many astrocytes and they formed neuron-astrocytic complex (N-ASC). Fos+/TH+/HRP+/GFAP+ and Fos+/VP+/HRP+/GFAP+ quadruplicate labeled N-ASC could be found in the MVZ, PVN and SON, respectively. The present results indicated that the neurons and astrocytes might be very active following hyperosmotic pressure and N-ASC as a functional unit might serve to modulate osmotic pressure. There were reciprocal osmoregulation pathways between the MVZ and SON or PVN in the brain.
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PMID:Reciprocal pathway between medullary visceral zone and hypothalamic supraoptic nucleus or paraventricular nucleus involved in hyperosmotic regulation. 1872 99