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)

We studied the distribution of tyrosine hydroxylase (TH) immunoreactive (IR) neurons in the adult human hypothalamus using a modification of the peroxidase-antiperoxidase immunohistochemical method which can be applied on autopsy brain material following prolonged formalin fixation. We observed that most of the TH-IR perikarya localized within the paraventricular (PVN) and supraoptic (SON) nuclei were large and showed homogeneous staining over the entire cytoplasm and processes. These results show that in the human brain a large population of neurons within the neurosecretory nuclei are able to synthesize a catecholamine.
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PMID:Tyrosine hydroxylase-immunoreactive neurons in paraventricular and supraoptic nuclei of the human brain demonstrated by a method adapted to prolonged formalin fixation. 168 32

Retrograde tracing techniques were used to identify supraspinal neurons that project to sacral, lumbar and cervical levels of the spinal cord in the gray short-tailed Brazilian opossum, Monodelphis domestica. Injections of Fast Blue, True Blue or wheat germ agglutinin conjugated to horseradish peroxidase into the sacral or lumbar cord labeled neurons in hypothalamic and brainstem nuclei reported to innervate the same levels in other mammals. Injections at cervical levels produced extensive labeling in the same areas as well as labeling within the isocortex, the medial preoptic area, the central and basomedial amygdaloid nuclei, the medial and interposed nuclei of the cerebellum, and several additional areas of the brainstem. In some of the cases, lumbar injections of wheat germ agglutinin conjugated to horseradish peroxidase were combined with a contralateral hemisection of the thoracic cord in order to determine laterality. The origins of monoaminergic projections were assessed using the retrograde transport of True Blue from the cervical cord and immunofluorescence for serotonin and tyrosine hydroxylase. Our results suggest that the origins of supraspinal projections to the spinal cord of Monodelphis are similar to those described for the North American opossum, Didelphis virginiana. Differences appear to exist, however, particularly in the amount of isocortex containing corticospinal neurons, the existence of spinal projections from the amygdala and preoptic area, the degree of rubrospinal somatotopy, and the origins of certain monoaminergic projections.
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PMID:The origins of supraspinal projections to lumbosacral and cervical levels of the spinal cord in the gray short-tailed Brazilian opossum, Monodelphis domestica. 168 17

A enzyme-linked immunosorbent assay has been developed for tyrosine hydroxylase (TH). The method uses a polyclonal antibody to trap TH, a monoclonal antibody to bind the immobilized TH, a biotinylated, anti-mouse immunoglobulin to bind the monoclonal antibody, and streptavidin covalently coupled to horseradish peroxidase (SA-HRP). The antigen-antibody complex is detected colorometrically following incubation with an HRP substrate. The method detects less than 1 ng (16 fmol) of TH and can be performed in 3 h. The high specificity of the assay is attributed to the use of both polyclonal and monoclonal antibodies, each of which are specific for TH. Data acquisition and reduction is rapid and linked directly to a common desktop computer. Levels of TH protein average 1 ng/microgram protein in striatum and, following treatment with the neurotoxicant MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), are decreased to a similar extent as is catalytic activity. In contrast, MPTP did not alter TH homospecific activity. The monoamine oxidase B inhibitor deprenyl blocked both the decrease in activity and the decrease in immunoreactive protein caused by MPTP.
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PMID:Measurement of tyrosine hydroxylase apoenzyme protein by enzyme-linked immunosorbent assay (ELISA): effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal tyrosine hydroxylase activity and content. 168 29

The levels of the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) are known to be closely regulated by neural feedback. Moreover, we have shown that intensity of TH-immunoreactivity varies with afferent input to the A10 group of dopaminergic neurons in the rat ventral tegmental area (VTA). This region is extensively and heterogeneously innervated by GABAergic afferents that mediate a number of different behavioral responses to iontophoretically applied GABA mimetics. We sought to determine: (1) whether there was an ultrastructural substrate for GABAergic innervation of TH-immunoreactive neurons; and (2) whether detectable TH-immunoreactivity varied in proportion to their GABAergic input in the two major subdivisions of the VTA, the parabrachial pigmentosus and paranigral subnuclei. Rabbit antiserum to TH and rat antiserum to GABA were visualized in single coronal sections of acrolein-fixed rat brain using a combination of peroxidase-antiperoxidase (PAP) and immunoautoradiography (ARG) or PAP and silver-intensified immunogold (SIG). Two dual-labeling electron microscopic immunocytochemical methods were employed to optimize detection of antigens and to more accurately quantify densities of TH-immunoreactivity and types of synaptic associations. Ninety-six GABA-labeled terminals (43 in the parabrachial and 53 in the paranigral subdivisions) were examined with PAP and ARG; 462 (238 in parabrachial and 224 in paranigral subdivisions) were examined with PAP and SIG. Analyses of both subnuclei yielded similar results; thus, the data were combined. With both methods, most GABA-labeled terminals (63% for SIG, 66% for PAP) formed direct synapses with TH-labeled profiles. These synaptic specializations were symmetric, the type thought to mediate inhibition. In single sections where GABA-labeled terminals were presynaptic to TH-labeled profiles, they comprised 45% (PAP) to 54% (SIG) of the total number of synaptic inputs onto TH-labeled cell bodies and 65% (SIG) to 80% (PAP) of the synaptic input onto TH-labeled dendrites. This value would be significantly less, if the analysis included all sections containing only GABA or TH irrespective of their synaptic relationships. The density of TH-immunolabeling, whether low (light) or high (intense), was determined in PAP- and SIG-labeled tissue. By both labeling methods, the numbers of GABA-immunopositive terminals forming synapses with lightly and intensely TH-immunoreactive profiles appeared equal. However, lightly TH-labeled neurons received fewer synaptic contacts from unlabeled terminals and, consequently, received proportionally more GABA-labeled terminals. GABA-labeled and unlabeled terminals were often in direct apposition to each other and were surrounded laterally, but not separated from each other, by astrocytic processes.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:GABA-labeled terminals form proportionally more synapses with dopaminergic neurons containing low densities of tyrosine hydroxylase-immunoreactivity in rat ventral tegmental area. 168 38

We have developed a double labeling immunocytochemical method utilizing peroxidase conjugated Fab fragments and 125I-labeled protein A to localize two neuronal markers on the same light or electron microscopic section with primary antibodies raised in the same animal species. The technique is applicable to the study of chemical connectivity in the brain, as illustrated by data obtained in the hypothalamus using rabbit polyclonal antisera against tyrosine hydroxylase (TH), phenylethanolamine-N-methyltransferase (PNMT), neuropeptide Y (NPY), and vasoactive intestinal peptide (VIP). Moreover, due to a high level of sensitivity and resolution, the technique offers considerable advantages over many previously developed dual labeling immunocytochemical methods for the demonstration of transmitter axonal co-localizations. Utilizing the peroxidase Fab/[125I]protein A method, we present here the first direct evidence that PNMT is present in many endings also containing NPY in the thalamic and hypothalamic paraventricular nuclei and in the arcuate nucleus. The method also may be combined as required with other labeling methods for localizing more than two neurochemical markers on one and the same electron microscopic section.
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PMID:Dual immunocytochemistry using 125I-labeled protein A: a new electron microscopic technique applied to the investigation of chemical connectivity and axonal transmitter co-localization in the brain. 168 61

Frozen and vibratome sections from the adrenal gland of the rat were hybridized in situ using a biotinylated oligonucleotide probe specific for tyrosine hydroxylase (TH) messenger ribonucleic acid (mRNA). Hybridization was detected using the streptavidin-peroxidase-diaminobenzidine (DAB) system in combination with silver-gold postintensification. The signal appeared as a black coloration and was localized to the cytoplasm of catecholamine-synthesizing chromaffin cells in the adrenal medulla. This coloration was due to the deposition of the silver-gold intensified DAB chromogen onto the probe hybridized to mRNA in carrier organelles. Compared with the conventional peroxidase-DAB labelling, the silver-gold amplified version was more sensitive in detecting TH mRNA. Using this modification, we were able to adapt the procedure to electron microscopy, thereby further localizing the hybridized signal to ribosomes. Because this hybridization detection system produces grains, not just color, this method has the potential for measurement of changes in mRNA levels at the ultrastructural level.
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PMID:Amplification of the in situ hybridization signal by silver postintensification: the biotin-dUTP-streptavidin-peroxidase diaminobenzidine-silver-gold detection system. 168 63

The study of the deep pineal gland of the Mongolian gerbil and other neuronal tissue from the rat by means of confocal laser scanning microscopy (CLSM) is described. Opical serial sectioning was performed on thick (100-200 microns) sections of the deep pineal gland of the Mongolian gerbil stained immunohistochemically using antisera to S-antigen and tyrosine hydroxylase (TH). Both dual-stained and single-stained material was examined using the fluorochromes fluorescein isothiocyanate (FITC) and Texas Red. High resolution images were obtained showing that pinealocytes have 1-3 processes that extend primarily to other pinealocytes or presumptive pinealocytes. Pinealocytes are located within the deep pineal gland as well as adjacent to the posterior aspect of the medial habenular nuclei. Pinealocyte processes were not seen extending into the habenular nuclei, but rather ended within the deep pineal gland a significant distance from their perikarya. The TH-immunopositive fibers were distributed throughout the deep pineal gland, often forming "baskets" of fibers around pinealocytes rather than being associated primarily with blood vessels. Other uses of the confocal microscope are demonstrated on rat neural tissue reacted with peroxidase/diaminobenzidine (DAB) immunohistochemistry and FITC fluorescence immunohistochemistry (paraventricular nucleus) as well as Golgi-stained neuronal tissue (cerebral cortex). The HRP/DAB and Golgi-stained images were visualized using the reflected image mode of the confocal system.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Application of confocal laser scanning microscopy to the deep pineal gland and other neural tissues. 168 36

Physiological and pharmacological studies have suggested that catecholamines modulate cholinergic neurons in the medial septal and diagonal band nuclei (i.e., the septal complex). Thus, the ultrastructural morphology of neurons containing choline acetyltransferase (ChAT), the biosynthetic enzyme for acetylcholine, and their relation to catecholaminergic terminals exhibiting immunoreactivity for the catecholamine synthesizing enzyme tyrosine hydroxylase (TH) were examined in the rat septal complex. Dual immunoautoradiographic and peroxidase anti-peroxidase labeling methods were used to simultaneously localize antibodies raised in rabbits against TH and from rat-mouse hybridomas against ChAT in single sections. At least two types of perikarya with ChAT-immunoreactivity (ChAT-I) were observed. The first type were large (20-30 microns), elongated or round, and contained a small indented nucleus with an abundant cytoplasm and an occasional lamellar body. The second type was also either ovoid or round but was medium-sized (15-20 microns) and contained a larger indented nucleus and a smaller amount of cytoplasm than the first type. Both types of perikarya as well as dendrites with ChAT-I were surrounded by astrocytic processes apposed to most of their plasmalemmal surfaces. The distribution and types of terminal associations (i.e., asymmetric synapses, symmetric synapses and appositions which lacked a membrane specialization in the plane of section analyzed) with ChAT-labeled perikarya and dendrites were quantitatively evaluated. The majority (68% of 197) of the presynaptic terminals were unlabeled; the remaining terminals were immunoreactive for TH (25%) or ChAT (7%). All three types of terminals contacted primarily the shafts of small dendrites and more rarely ChAT-labeled perikarya and large dendrites. ChAT-labeled terminals: (1) formed associations with unlabeled perikarya and dendrites (31% of 176); (2) formed associations with perikarya and dendrites with ChAT-I (7%); (3) contacted the same unlabeled perikarya and dendrite as a TH-containing terminal (21%); (4) were in apposition to TH-labeled terminals (25%); or (5) were either in apposition to unlabeled or ChAT-labeled terminals or lacked associations with any processes. The majority of associations formed by the terminals with ChAT-I were on the shafts of small dendrites. Moreover, most of the associations formed were either symmetric synapses or appositions not separated by astrocytes in the plane of section analyzed. These findings provide cellular substrates in the septal complex (1) for sparse synaptic input relative to astrocytic investment of cholinergic neurons and (2) for direct synaptic modulation of cholinergic and non-cholinergic neurons by catecholamines and/or acetylcholine. These findings have direct relevance to catecholaminergic-cholinergic interactions and to the neuropathological basis for Alzheimer's disease.
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PMID:Cholinergic neurons in the rat septal complex: ultrastructural characterization and synaptic relations with catecholaminergic terminals. 168 77

Neurotensin and catecholamines in the central nucleus of the amygdala (CNA) have both been implicated in the integration of autonomic responses to stress. We examined whether there might be a cellular substrate for interactions involving these putative neurotransmitters in the CNA. Sections of acrolein-fixed rat brain were processed either (1) for the ultrastructural localization of a rat antiserum against neurotensin using the peroxidase-antiperoxidase (PAP) method, or (2) for the dual localization of rat neurotensin antiserum and rabbit antiserum against the catecholamine-synthesizing enzyme, tyrosine hydroxylase (TH), using the PAP method and immunoautoradiography. The rat polyclonal antiserum against neurotensin was shown in immunoblots to recognize neuromedin N and Lys-Arg-neurotensin (LANT-6) in addition to neurotensin. In single and dual labeling studies, the neurotensin-like immunoreactivity (NTLI) was detected in perikarya and processes. The NTLI was localized predominantly to dense core vesicles in one group of perikarya and dendrites, while a second group had labeling both in dense core vesicles and more diffusely throughout the cytoplasm. Terminals also showed NTLI, particularly in association with dense core vesicles. The labeled terminals formed primarily symmetric junctions with both cell bodies and dendrites. In the dual labeling study, perikarya contained only NTLI while terminals contained TH and/or NTLI. Terminals containing TH or NTLI separately innervated cell bodies and dendrites displaying NTLI, and formed separate or convergent inputs onto unlabeled neuronal targets. Terminals colocalizing both TH and NTLI formed junctions only on unlabeled dendrites. These findings show that in the rat CNA two populations of neurons differ with respect to their distribution of NTLI, and that the output from neurons containing NTLI is modulated by direct synaptic input from terminals containing neurotensin and/or catecholamines. Release of neurotensin and catecholamines, most likely dopamine, from the same or separate terminals on common targets in the CNA may account for certain similarities in their stress-related functions.
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PMID:Vesicular and cytoplasmic localization of neurotensin-like immunoreactivity (NTLI) in neurons postsynaptic to terminals containing NTLI and/or tyrosine hydroxylase in the rat central nucleus of the amygdala. 168 86

The present study sought to establish the cellular basis for the catecholaminergic (i.e., noradrenaline and dopamine) modulation of neurons in the horizontal limb of the diagonal band of Broca (HDB) in the rat brain. The light and electron microscopic localization of antigenic sites for a polyclonal antibody directed against the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH), were examined in the HDB using a double-bridged, peroxidase-antiperoxidase method. By light microscopy, numerous punctate, varicose processes with intense TH-immunoreactivity (TH-I) were detected in the HDB. Additionally, a few small, bipolar, or multipolar TH-immunoreactive neurons were observed. Ultrastructural analysis of single sections revealed that the TH-labeled processes were axons and axon terminals. Axons (n = 134) with TH-I were primarily unmyelinated. Terminals with TH-I (n = 169) were 0.3-1.4 microns in diameter and contained many small, clear vesicles and 0-5 larger dense-core vesicles. The types of associations (i.e., asymmetric synapses, symmetric synapses, and appositions which lacked a membrane specialization in the plane of section analyzed) formed by the TH-labeled terminals were quantitatively evaluated. The TH-labeled terminals: (1) formed associations with unlabeled perikarya and dendrites (134 out of 169), (2) were closely apposed without glial intervention to unlabeled and TH-labeled terminals (11 out of 169), or (3) had no neuronal associations in the plane of section analyzed (24 out of 169). The relatively rare (n = 4) associations with unlabeled perikarya were mostly characterized by symmetric synaptic specializations. The majority of the TH-labeled terminals were associated with the shafts of small dendrites (66% of 134). Moreover, most of the associations on dendrites and dendritic spines were further characterized by asymmetric synaptic specializations; however, many were also appositions without any apparent glial intervention in the plane of section analyzed. Additionally, the TH-labeled terminals were often associated with only one dendrite, which, in the same plane of section, was sparsely innervated by other terminals. Astrocytic processes usually surrounded the portions of the terminals and dendrites not involved in the region of association. The TH-immunoreactive perikarya were small (7-12 microns), ovoid, and had an indented nucleus with some heterochromatin. Their scant cytoplasm contained mitochondria, Golgi complexes, and endoplasmic reticulum. A few immunoreactive dendrites, presumably derived from the local neurons, were also detected. Both TH-immunoreactive perikarya and dendrites were associated primarily with unlabeled terminals, although a few terminals with TH-I also contacted them.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Ultrastructural localization of tyrosine hydroxylase immunoreactivity in the rat diagonal band of Broca. 168 18


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