Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intraocular injection of 120 nmol. of kainic acid, a powerful glutamate receptor agonist, induces a marked degeneration of cells in the inner nuclear layer of the retina. Within 2 hours after injection there is a significant decrement in the specific activities of tyrosine hydroxylase, choline acetyltransferase, and glutamic acid decarboxylase; by 48 hours after injection there is nearly a complete loss in the presynaptic neurochemical markers for the cholinergic and GABAergic neurons. The dopaminergic neurons, as assessed by activity of tyrosine hydroxylase and concentration of endogenous dopamine, are reduced only 50% by the kainic acid treatment. Although basal adenylate cyclase activity is unaffected by kainic acid, there is a 90 percent reduction in the activating effects of dopamine on adenylate cyclase in the kainic acid-treated retina.
 ...
PMID:Kainic acid: neurotoxic effects after intraocular injection. 83 74

We have shown that in embryos treated with ethanol in ovo during days 1-3, a critical period of neuroembryogenesis, cholinergic neuronal phenotypic expression is decreased whereas GABAergic and catecholaminergic neuronal populations are increased as assessed by neuronal markers choline acetyltransferase (ChAT), glutamic acid decarboxylase (GAD) and tyrosine hydroxylase (TH) respectively. In this study, ethanol was administered intracerebrally to embryos at embryonic day 8, embryos were sacrificed at day 9 and ChAT and GAD activities assayed separately in cerebral hemispheres and remaining brain (diencephalon-midbrain and optic lobes). We found that ChAT activity was enhanced in the cerebral hemispheres only, whereas GAD activity was decreased in both cerebral hemispheres and remaining brain. We have concluded that the differential responses of neuronal phenotypes to ethanol may reflect compensatory mechanisms to ethanol insult. Moreover, these findings emphasize the vulnerability of the GABAergic neuronal phenotypes to ethanol neurotoxicity during early brain development in the chick.
 ...
PMID:Differential sensitivity of cholinergic and GABAergic neurons in chick embryos treated intracerebrally with ethanol at 8 days of embryonic age. 135 Dec 51

Both aging and exercise are associated with alterations in circulating levels of catecholamines. To determine the interactions of age and exercise on tyrosine hydroxylase (TH) activity and TH mRNA, Fischer-344 female rats aged 5 months (young) and 25 months (old) were trained by treadmill running for 10 weeks. The elevation in maximum oxygen consumption in both groups was equivalent following exercise, indicating that training had occurred. In control rats, both TH activity and TH mRNA were greater in the older groups when compared with the younger animals. In young rats, exercise decreased TH activity by 25% and TH mRNA by 27%. In older rats, exercise was not associated with a decrease in TH activity and TH mRNA. Choline acetyltransferase activity (ChAT) was decreased and glutamic acid decarboxylase activity (GAD) was increased by exercise in young rats. The decrease in ChAT activity and increase in GAD activity suggest that trans-synaptic mechanisms play a role in the exercise-induced alteration of TH gene expression. Neither ChAT nor GAD was altered by exercise in older groups. Our data suggest that the previously reported diminution in catecholamines associated with exercise may be due to a decrease in TH mRNA and a resulting decrease in TH activity. There was no effect of exercise in the old rats, supporting previous observations that the plasticity of the sympathoadrenal system diminishes with age.
 ...
PMID:Modulation of tyrosine hydroxylase gene expression in the rat adrenal gland by exercise: effects of age. 135 55

Light-microscopical examination was carried out to investigate the emergence and development of several classes of immunoreactive cells in regenerating retinas of the adult newt (Triturus pyrrhogaster) after total retinal ablation. Immunoreactive proliferating cell nuclear antigen (ir-PCNA, a marker for replicating cells) was present in nuclei of all neuroblasts in the early mono-layered to several-layered stages (15-20 days after retinal ablation; days 15-20), but was lost progressively in an intermediate-to-central/peripheral order as cells and layers increased (days 20-25). Cells, which had lost ir-PCNA, began to separate to form the outer nuclear, inner nuclear and ganglion cell layers around days 25-30 (the cell separation stage). Finally, the location of ir-PCNA was restricted to a band of neuroblast cells at the retinal margin (days 30-35) as seen in intact adult retinas. Visinin-immunoreactive (ir) cells, mainly destined to be cones, appeared first singly or as clusters at the most distal layer in the intermediate region of retinas multi-layered with PCNA-ir neuroblasts, which was followed by appearance of opsin-ir rod outer segments and tyrosine hydroxylase-ir amacrine cells around the cell separation stage. Shortly later, cells respectively immunoreactive to glutamic acid decarboxylase, neuropeptide Y, serotonin, glucagon, glutamine synthetase, glial fibrillary acidic protein, substance P and protein kinase C were found to emerge also in an intermediate-to-central/peripheral sequence. Some of the glucagon-ir cells appeared to be of an interplexiform type.
 ...
PMID:An immunohistochemical study of regenerating newt retinas. 135 60

We have demonstrated the coexistence of GABA-like and tyrosine hydroxylase-like immunoreactivities (GABA-LI and TH-LI, respectively) in the same neurons of the rat locus ceruleus (LC). The profiles of these cells were labeled by alternately immunostaining adjacent sections for GABA-LI or TH-LI by the avidin-biotin-peroxidase complex method or the peroxidase-anti-peroxidase method after perfusion (either Zamboni's fixative or PPG), and observation at light and electron microscopic levels. For light microscopy, pairs of adjacent sections of more than 590 (Zamboni's) and 260 (PPG), and for electron microscopy, 40 ultrathin sections cut from adjacent semithin plastic sections (Zamboni's), were examined. GABA-LI was found in 80% (1,309/1,642 in total) of small and medium-sized neurons, uniformly scattered throughout the LC. Observations unequivocally show that the majority of GABA-ergic neurons are also noradrenergic. Several neurons are neither noradrenergic nor GABA-ergic, while other noradrenergic neurons do not show GABA-LI. It is shown that astrocytes, but not oligodendrocytes, contain GABA. In situ hybridization using a probe DNA fragment of the glutamic acid decarboxylase (GAD) cDNA, amplified by the polymerase chain reaction, detected GAD mRNA signals in many neurons throughout the LC, supporting the presence of a GAD/GABA system in the LC. Multiple "classical" transmitters, including GABA, serotonin, and noradrenaline, coexist in many LC neurons and may contribute to its widely diverging projections throughout the entire CNS.
 ...
PMID:Immunocytochemical and in situ hybridization evidence for the coexistence of GABA and tyrosine hydroxylase in the rat locus ceruleus. 136 Jul 72

By means of dual ultrastructural immunostaining the followings patterns are visualized: gamma-aminobutyric acid (GABA) immunoreactive neurons, dendrites, axons and axon terminals and tyrosine hydroxylase (TH) immunopositive fibers, varicosities and boutons in rat striatum. Additionally single glutamic acid decarboxylase (GAD) immunolabeling is carried out. Four subgroups of GABA and GAD immunoreactive striatal neurons are revealed. These neuronal types are identified on the basis of sectional diameters, nuclear form and nuclear envelope invaginations, quantity of cytoplasm and cell organelles. Plasmalemmal appositions between GABAergic and between GABAergic and immunonegative neurons are observed. All subgroups of striatal GABAergic neurons contact with GABA and GAD immunoreactive, TH immunoreactive and immunonegative boutons. In the striatal neuropil numerous GABAergic, dopaminergic and immunonegative axonal endings synapsed with dendrites and spines are found out. Massive dopaminergic striatal structures using dual immunostaining is evident. Some GABA and GAD immunoreactive dendrites are revealed in direct contact with capillary walls.
 ...
PMID:Gamma-aminobutyric acid, glutamic acid decarboxylase and tyrosine hydroxylase in rat striatum demonstrated by single and dual immunocytochemistry. 136 5

The distribution of substance P (SP), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD) immunoreactivity in the substantia nigra of the rat was studied by means of an ultrastructural double-labeling immunocytochemical method. Direct synaptic contact between SP-immunoreactive terminals and GAD-positive nigral neurons was more often observed in the pars lateralis than the pars reticularis and was rarely observed in the pars compacta. Substance P-positive terminals also formed synapses with cell bodies and dendrites of TH-positive, dopaminergic neurons in the pars compacta and pars reticulata. Multiple SP-immunoreactive terminals were often observed with symmetrical and, less frequently, asymmetrical synapses on individual TH-containing dendrites. Evidence of SP-containing terminals contacting both GABAergic and dopaminergic neurons in the substantia nigra suggests a direct excitatory action upon nigral projection neurons.
 ...
PMID:Substance P synaptic interactions with GABAergic and dopaminergic neurons in rat substantia nigra: an ultrastructural double-labeling immunocytochemical study. 137 84

In order to analyze the feedback action of prolactin (PRL) on the hypothalamus on the cellular level, we used primary cultures of rat embryonic diencephalon to measure the calcium response of individual neurons to PRL by means of fast fluorescence photometry. The cultures were subsequently stained with antibodies against the neuronal marker MAP-2, glutamic acid decarboxylase (GAD) or tyrosine hydroxylase (TH). PRL caused a rapid rise of intracellular free Ca2+ in a specific type of GABAergic neuron characterized by a spindle-shaped bipolar morphology and immunoreactivity to MAP-2 and GAD but not to TH. It is concluded that a subpopulation of hypothalamic GABAergic but not dopaminergic neurons react to PRL with a rapid increase in intracellular free Ca2+. These data are compatible with the assumption of a rapid negative feedback regulation of the secretion of PRL from the pituitary mediated by tuberoinfundibular GABAergic neurons.
 ...
PMID:Diencephalic GABAergic neurons in vitro respond to prolactin with a rapid increase in intracellular free calcium. 140 68

Immunoreactivities for tyrosine hydroxylase (TH), gamma-aminobutyric acid (GABA) and, in some cases, glutamic acid decarboxylase (GAD) were detected by light and electron microscopy in axons projecting into the median eminence and pituitary gland of various mammals (rats, mice, guinea pigs, cats, rabbits and hares). Light microscope immunoperoxidase reactions were performed on adjacent semithin sections of plastic-embedded samples. In the median eminence external zone, the distributions of the TH- and GAD- or GABA-immunoreactive endings were very similar in the anterior and lateral areas, while medially the GABA-labelled endings predominated. Comparable distribution patterns were found in the various species examined. In the pituitary gland, the distributions of GABA- and TH-immunoreactivities were superimposable in the intermediate lobes of all species examined, except in the rabbit and hare in which both types of innervation were lacking. For electron microscopy, the immunogold procedure was applied to sections of lowicryl-embedded samples; simultaneous detection of GABA- and TH-immunoreactivities was enabled by recto-verso double labelling with gold particles of distinct diameters. In the median eminence, GABA-immunoreactivity occurred systematically in the TH-positive endings, while distinct GABA-positive/TH-negative axons were also detected. In the intermediate lobe, the colocalization of TH- and GABA-immunoreactivities was a constant feature of the axons innervating the melanotrophic cells in all the species examined, except in the Leporidae. The functional significance of this colocalization remains to be determined.
 ...
PMID:Systematic presence of GABA-immunoreactivity in the tubero-infundibular and tubero-hypophyseal dopaminergic axonal systems: an ultrastructural immunogold study on several mammals. 167 30

Transneuronal regression in substantia nigra reticulata (SNR) and substantia nigra compacta (SNC) neurons was studied in Fischer 344 male rats by immunocytochemistry and by in situ hybridization. Three months after striatal lesioning by ibotenic acid, there was a shrinkage (30%) of the SNR region cross-sectional area and a 50% disappearance of neurons that contain glutamic acid decarboxylase (GAD)-mRNA, but only in the ventromedial portion of this nucleus. Loss of dopaminergic neurons, as recognized by tyrosine hydroxylase immunoreactivity, occurred only in caudal portions of the SNC and SNR. These findings suggest that lesions in reciprocally connected pathways, like the nigrostriatal and striatonigral systems, may produce a vicious cycle (feedforward cascade) of neurodegeneration due to interference with retrograde ana anterograde influences.
 ...
PMID:Disappearance of GAD-mRNA and tyrosine hydroxylase in substantia nigra following striatal ibotenic acid lesions: evidence for transneuronal regression. 167 92


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>