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)

One of the major pathways of information flow through the basal ganglia is the pallidonigrofugal system. In order to better understand this system in the rat, experiments have been performed to study the topography, synaptic organization, and neurotransmitter content of the pallidonigral projection and to determine whether the pallidonigral neurones make direct synaptic contacts with nigrofugal cells. This was achieved by combining the anterograde transport of the lectin Phaseolus vulgaris-leucoagglutinin (PHA-L) with the retrograde transport of lectin-conjugated horseradish peroxidase (WGA-HRP), postembedding immunocytochemistry for gamma-aminobutyric acid (GABA), and pre-embedding immunocytochemistry for tyrosine hydroxylase (TH). Following injections of PHA-L in different regions of the lateral part of the globus pallidus, a substantial number of immunoreactive fibres and terminals occurred in the ipsilateral substantia nigra reticulata (SNr). The immunoreactive elements were distributed according to a rostral to medial and caudal to lateral topography. Injections that were restricted to the medial tip of the globus pallidus led to the anterograde labeling of a small number of fibres that were sparsely distributed in the SNr. The most characteristic feature of the pallidonigral fibres was the presence of large varicosities that were often grouped to form pericellular baskets. Injections of WGA-HRP in the ventromedial thalamic nucleus, superior colliculus, or midbrain tegmentum, including the pedunculopontine nucleus, showed that the perikarya and primary dendrites of the output cells of the SNr were often surrounded by the large pallidonigral varicosities. The number of varicosities surrounding a single cell varied from 2-12. Electron microscopic analysis showed that the varicosities contained round or slightly pleomorphic vesicles and numerous mitochondria and that they established symmetrical synaptic contacts. Quantitative measurements revealed that the varicosities had a maximum diameter varying from 0.5 to 2.5 microns and a mean cross-sectional area of 0.76 +/- 0.25 microns 2 (N = 237, mean +/- S.D.). The postsynaptic structures of the pallidonigral varicosities included perikarya (48%), large dendrites (38%), and small dendrites (14%). A large proportion of these postsynaptic targets were retrogradely labeled after injection of WGA-HRP in the ventromedial thalamic nucleus, superior colliculus, or midbrain tegmentum. Postembedding immunocytochemistry was used to show that the pallidonigral axons and terminals in contact with nigrofugal neurones displayed GABA immunoreactivity. The use of a double immunocytochemical method revealed, that in addition to the nondopaminergic SNr output neurones, the dendrites and perikarya of the substantia nigra pars compacta (SNc) receive an input from the globus pallidus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The output neurones and the dopaminergic neurones of the substantia nigra receive a GABA-containing input from the globus pallidus in the rat. 169 89

The co-expression of somatostatin (SOM)- and tyrosine hydroxylase (TH)-like immunoreactivities in nerve cells of the rat hypothalamus was investigated by the simultaneous application to the same sections of immuno-beta-galactosidase staining and the peroxidase-antiperoxidase (PAP) method. SOM-like immunoreactive cells stained blue with immuno-beta-galactosidase staining and TH-like immunoreactive cells stained brown with the PAP method. Double-labeled cells with overlapping blue and brown immunoreaction products were frequently identified in the preoptic periventricular nucleus (pope). These double-labeled cells were seen in clusters within the ventral half of the rostral pope. The periventricular hypothalamic nucleus at the level of the anterior hypothalamic nucleus contained only scattered nerve cells with both SOM- and TH-like immunoreactivities, despite the presence of many nerve cells immunoreactive for either SOM or TH in this nucleus. Double-labeled cells were also observed in some regions of the medial-basal hypothalamus, including the boundary between the ventromedial hypothalamic nucleus and the arcuate hypothalamic nucleus, and areas dorsal and lateral to the ventromedial hypothalamic nucleus. These findings may provide insight into the mechanisms underlying previously described catecholamine-mediated modulation of SOM release from the hypothalamus.
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PMID:Somatostatin co-localizes with tyrosine hydroxylase in the nerve cells of discrete hypothalamic regions in rats. 169 11

The nucleus accumbens septi (Acb) represents an interface between limbic and motor systems and a site for modulation of these integrative functions by ascending catecholaminergic, principally dopaminergic, axons. This modulatory regulation is most likely attributed to pre- or postsynaptic associations between limbic telencephalic and brainstem afferents. In the present investigation, we examined the ultrastructure and synaptic associations of hippocampal afferents, as well as their relation to catecholaminergic terminals, in the medial Acb of adult rats. Hippocampal afferents were identified by anterograde transport of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) injected in the ventral subiculum, and by anterograde degeneration seen 2-3 days following lesion of the fimbria. Specific comparisons between these methods were made (1) to determine whether similar populations of terminals were labeled and (2) to assess the feasibility of combining degeneration with immunoperoxidase labeling for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). Hippocampal afferents labeled with HRP were finely myelinated or unmyelinated and gave rise to small terminals (mean diameter 0.58 micron) containing mostly clear, round vesicles. Of the HRP-labeled terminals which made recognizable junctions, 85% (104/122) formed asymmetric synapses with the heads of dendritic spines. The remainder either formed asymmetric axodendritic synapses or symmetric junctions. Degenerating terminals were significantly smaller (mean diameter 0.35 micron) than terminals labeled with HRP. However, these also formed principally asymmetric axospinous synapses (89/102, 87%). Whether identified by HRP transport or anterograde degeneration, the hippocampal afferents comprised approximately 10% of all terminals and 30% of all asymmetric axospinous synapses in the medial Acb. In contrast to hippocampal afferents, TH-labeled terminals formed primarily symmetric contacts with dendritic shafts and the heads and necks of spines. Quantitative analysis of sections containing both anterograde degeneration and TH-immunoreactivity showed that 25% (26/104) of associations formed by degenerating hippocampal terminals involved convergent inputs with TH-labeled terminals on the same postsynaptic structure. These included dual input either to the same spine head or to different parts of the same dendrite. In addition, the plasma membranes of hippocampal and TH-labeled terminals were often directly apposed to each other (10/58, 17% of axo-axonal associations formed by degenerating terminals), without recognizable synaptic specializations.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In the rat medial nucleus accumbens, hippocampal and catecholaminergic terminals converge on spiny neurons and are in apposition to each other. 170 38

The purpose of the present study was to determine whether neurochemicals normally found within neuron somata, fibers, and terminals of the hippocampal formation would also be present in transplanted hippocampal tissue that had developed in lesion cavities made in adult rat brains by aspiration of the hippocampus and overlying dorsolateral neocortex. Embryonic Day 15 or 16 rat brian tissue containing hippocampus with some medial pallial anlage was transplanted into the site of hippocampal aspiration lesions in adult male rats. One hundred ten to one hundred thirty-five days later the brains of these rats were sectioned and processed using the avidin-biotin-horseradish peroxidase immunocytochemical procedure to visualize choline acetyltransferase, met-enkephalin (MENK), neurotensin (NT), somatostatin, substance P, tyrosine hydroxylase (TH), or vasoactive intestinal polypeptide. Sections from two brains were stained using the thiocholine technique for visualization of acetylcholinesterase. All of these substances were found within cell bodies and/or fibers in the transplants. However, several abnormalities were noted. In addition to TH-immunoreactive fibers, TH-immunoreactive cell bodies were found in the transplants. Since TH is not expressed in mature hippocampal or cortical neurons this suggests that mechanisms for suppression of manufacture of this enzyme are lacking or inhibited in the transplants. Further, although all of the peptides were present either in fibers or in both cell bodies and fibers, the density of staining for NT and MENK was less than would be expected for normal hippocampus, and none of the cell bodies or fibers reacting for the peptides exhibited any apparent organization resembling that normally observed in hippocampus or cortex. However, some histological organization was present and the cholinergic markers were associated with this organization. These data suggest that some tropic and/or trophic factor such as nerve growth factor is present in the transplants to guide cholinergic innervation.
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PMID:Neurochemical anatomy of fetal hippocampus transplanted into large lesion cavities made in the adult rat brain. 170 34

In order to examine the synaptic input to dopaminergic neurones in the substantia nigra from GABAergic terminals and terminals that contain substance P, double and triple immunocytochemical studies were carried out at the light and electron microscopic levels in the rat. In a first series of experiments sections of the substantia nigra were incubated to reveal axon terminals containing either substance P or glutamate decarboxylase and then incubated to reveal dopaminergic neurones using tyrosine hydroxylase immunocytochemistry. Examination of this material in the light microscope revealed that many substance P- and glutamate decarboxylase-immunoreactive boutons were associated with the dopaminergic cells. In the electron microscope it was found that the perikarya and dendrites of the dopaminergic neurons received symmetrical synaptic input from terminals that displayed immunoreactivity for substance P or glutamate decarboxylase. A small proportion of the substance P-positive boutons formed asymmetrical synapses. In a second series of experiments sections of the substantia nigra were processed by the pre-embedding immunocytochemical technique for tyrosine hydroxylase and then the post-embedding immunogold technique for gamma-aminobutyric acid (GABA). Examination in the electron microscope revealed that the tyrosine hydroxylase-positive neurons received symmetrical synaptic input from many GABA-positive terminals. Quantitative analyses demonstrated that a minimum of 50-70% of all boutons afferent to the dopaminergic neurones display glutamate decarboxylase or GABA immunoreactivity. Triple immunocytochemical studies i.e. pre-embedding immunocytochemistry for tyrosine hydroxylase and substance P, combined with post-embedding immunogold staining for GABA, revealed that some of the substance P-immunoreactive boutons that were in contact with the dopaminergic neurones also displayed GABA immunoreactivity. In a third series of experiments the combination of anterograde transport of lectin-conjugated horseradish peroxidase or biocytin with post-embedding GABA immunocytochemistry demonstrated that at least one of the sources of GABA-containing terminals in the substantia nigra is the striatum. The results of the present study: (1) demonstrate that dopaminergic neurones in the substantia nigra receive symmetrical synaptic input from GABAergic and substance P-containing terminals, (2) show that a proportion of these terminals contain both substance P and GABA and (3) suggest that the major synaptic input to dopaminergic neurones is from GABAergic terminals and that a part of this innervation is derived from the striatum.
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PMID:The GABA and substance P input to dopaminergic neurones in the substantia nigra of the rat. 170 87

A method is described that allows an estimation of the neurotransmitter-related immunoreactivity, morphology and relationship to other immunoreactive elements, of single functionally identified neurons in the central nervous system. First, neurons are identified electrophysiologically using intracellular recording and labelled by iontophoresis of lucifer yellow (LY). After fixation and sectioning of the brain tissue, the location of the labelled neuron is determined by fluorescence microscopy. Sections are then processed using an indirect immunofluorescence procedure in order to determine the antigen content of the labelled neurons. Antisera to LY and an avidin-biotin immunoperoxidase technique is then used to localize LY in a permanent form, while the other previously localized antigen is permanently visualised by using the fluorescent-labelled second antibody as a bridge antibody in a peroxidase anti-peroxidase technique. The method is illustrated by an examination of neurons in the medulla oblongata of the rat, that have been stained intracellularly with LY, their content of tyrosine hydroxylase assessed, and their relationship to other tyrosine hydroxylase immunoreactive neurons determined.
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PMID:Dual fluorescence combined with a two-color immunoperoxidase technique: a new way of visualizing diverse neuronal elements. 171 61

The serous lingual glands of von Ebner secrete lingual lipase, an enzyme that begins fat digestion in the stomach. The objective of this study was to characterize the neuromodulators in the rat tongue and von Ebner glands using immunocytochemical techniques. Rat lingual tissues were fixed in formalin, embedded in paraffin and sectioned at 4 microns for light microscopic studies. Immunocytochemical localization of neuromodulators was performed with monospecific anti-rat neuromodulator IgG or control (preimmune) IgG as the primary antibody, using the peroxidase-antiperoxidase (PAP) technique. No staining was seen with control anti-rat IgG. Immunospecific staining for vasoactive intestinal peptide (VIP), tyrosine hydroxylase and choline acetyltransferase (CHAT) was observed in nerves in the tongue, and cells containing immunospecific staining for serotonin (5-hydroxytryptamine) were seen in the stroma between the lingual glands. Selected cells in the serous glands stained positively for the presence of substance P and somatostatin. Adrenergic, VIP-containing and cholinergic nerves appear to innervate the tongue and serous glands. Substance P and somatostatin were identified in cells of the lingual serous glands and may be additional local modulators regulating lingual lipase release.
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PMID:Neuromodulators of the lingual von Ebner gland: an immunocytochemical study. 171 11

The vast majority of striatonigral projection neurons in pigeons contain substance P (SP), and the vast majority of SP-containing fibers terminating in the substantia nigra arise from neurons in the striatum. To help clarify the role of striatonigral projection neurons, we conducted electron microscopic single- and double-label immunohistochemical studies of SP+ terminals and/or dopaminergic neurons (labeled with either anti-dopamine, DA, or anti-tyrosine hydroxylase, TH) in pigeons to determine: (1) the synaptic organization of SP+ terminals, (2) the synaptic organization of TH+ perikarya and/or dendrites, and (3) the synaptic relationship between SP+ terminals and TH+ neurons in the substantia nigra. Tissue single-labeled for SP revealed numerous SP+ terminals contacting thin unlabeled dendrites in the substantia nigra, but few SP+ terminals were observed contacting perikarya or large-diameter dendrites. SP+ terminals contained round, densely packed, clear vesicles, and often contained one or more dense-core vesicles. Synaptic junctions between SP+ terminals and their targets were more often symmetric (86%) than asymmetric. In tissue single-labeled for DA, we observed few terminals contacting DA+ perikarya, whereas terminals contacting DA+ dendrites were more abundant. Terminals contacting DA+ structures comprised at least four different morphologically distinct types based on the morphology of the clear synaptic vesicles and the type of synaptic junction. One type of terminal contained round clear vesicles and made symmetric synapses, and thus resembled the predominant type of SP+ terminal. The second type contained round clear vesicles and made asymmetric synapses, the third type contained medium-size pleomorphic clear vesicles and made symmetric synapses, and the fourth type contained small pleomorphic clear vesicles and made symmetric synapses. The presence of contacts between SP+ terminals and dopaminergic dendrites in the substantia nigra was directly demonstrated in tissue double-labeled for SP (by the peroxidase-antiperoxidase procedure, or PAP, with diaminobenzidine) and TH (by either the silver-intensified immunogold procedure or the PAP procedure with benzidine dihydrochloride). SP+ terminals commonly contacted thin TH+ dendrites in the substantia nigra, but few SP+ terminals contacted large-diameter TH+ dendrites or perikarya. Synapses between SP+ terminals and TH+ neurons were always symmetric. TH+ dendrites also were contacted by terminals not labeled for SP, which were more abundant than were SP+ terminals. Non-TH+ neurons were also contacted by both SP+ terminals and non-SP+ terminals.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Ultrastructural single- and double-label immunohistochemical studies of substance P-containing terminals and dopaminergic neurons in the substantia nigra in pigeons. 171 17

Direct projections from serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) to the ventromedial hypothalamic nucleus (VMH) in the rat were investigated by the retrograde horseradish peroxidase tracing method combined with the immunocytochemical technique. Serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive PAG neurons sending their axons to the VMH were distributed in the ventrolateral subnucleus and ventral portion of the medial subnucleus of PAG at the middle and caudal levels.
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PMID:Serotonin-, substance P- and tyrosine hydroxylase-like immunoreactive neurons projecting from the periaqueductal gray to the ventromedial hypothalamic nucleus in the rat. 172 16

We localized serotonin (5-HT), leu-enkephalin (LENK), and tyrosine hydroxylase (TH) immunoreactive cells in the brain of a holocephalian, Hydrolagus colliei, by use of antibodies made in rabbit and the peroxidase-antiperoxidase technique. Only three locations contained TH+ cells, the caudal myelencephalon, the locus coeruleus, and the diencephalon. Of these locations, the diencephalon contained the most cells and the locus coeruleus the least cells. The caudal TH+ myelencephalic cells formed a single large group that spanned both the dorsal and ventral portions of the brain (A1A2). The diencephalic TH+ cells were located in the posterior tuberculum, in the ventromedial and ventrolateral thalamic nuclei, and in the inferior lobe of the hypothalamus. Hydrolagus differed from mammals and the elasmobranchs, their sister group, in that no substantia nigra (A9), ventral tegmental area (A10), or A5 cell group was found. Distribution of LENK+ and 5-HT+ cells were similar to each other; the raphe nuclei contained most of the 5-HT+ and LENK+ cells. These 5-HT+ and LENK+ cells were found at all rostrocaudal levels of the myelencephalon. The nucleus reticularis magnocellularis, reticularis paragigantocellularis lateralis, the ventral met- and mesencephalon (B7 and B9 cell groups), the hypothalamus, and the pretectal area contained additional 5-HT+ and LENK+ cells. The solitary complex contained LENK+ cells but not but 5-HT+ cells. A dorsal raphe nucleus, which is the largest 5-HT+ cell group in mammals, was absent in Hydrolagus. A dorsal raphe nucleus is present in one galeomorph shark radiation but is absent in three radiations of batoids (rays, skates, and guitarfish). Thus even within cartilaginous fish, there are differences in the distribution of neurochemicals and possibly nuclei within their brains.
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PMID:Immunohistochemical localization of serotoninergic, enkephalinergic, and catecholaminergic cells in the brainstem and diencephalon of a cartilaginous fish, Hydrolagus colliei. 191 46


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