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)

Neural retinas of genetically modified mouse embryos and fetuses entirely lacking extraocular striated muscles (designated as Myf5-/-:MyoD-/- or amyogenic) are used to study in vivo the role of extraocular muscle (i.e., fetal ocular movements) in the genesis of retinal cell diversity. Although retinal lamination and the total number of cells per retinal layer appeared unaffected in amyogenic fetuses, electron microscopy and histochemistry revealed the absence of cholinergic amacrine cell type. By contrast, the amounts of other amacrine cell subpopulations (calretinin-, tyrosine hydroxylase-, and parvalbumin-expressing) were increased, whereas the amounts of Islet1/2-expressing retinal ganglion cells were decreased. Surprisingly, it was not possible to detect any change in proliferation or cell death. Consistently, the number of progenitors for retinal ganglion cells (nestin-expressing precursors) were increased, whereas the amounts of precursors for amacrine cells (syntaxin- and VC1.1-expressing precursors) were decreased in the mutant retinas. The difference in requirements for extraocular muscle support in regulation of precise ratios of retinal neuronal cell types suggests an essential role of extrinsic cues in the determination of retinal cell fates. Taken together, it appears that patterning mechanisms intrinsic to the neural retina specify the basic organization of retinal spatial organization (e.g., retinal layers and total number of cells). However, extrinsic cues seem to change intrinsic properties (e.g., competence) of retinal progenitor cells and influence the ratios of the differentiated cell types (i.e., cell fate choice) they produce.
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PMID:Determination of retinal cell fates is affected in the absence of extraocular striated muscles. 1261 34

Although the rabbit brain, in particular the basal forebrain cholinergic system, has become a common model for neuropathological changes associated with Alzheimer's disease, detailed neuroanatomical studies on the morphological organization of basal forebrain cholinergic nuclei and on their output pathways are still awaited. Therefore, we performed quantitative choline acetyltransferase (ChAT) immunocytochemistry to localize major cholinergic nuclei and to determine the number of respective cholinergic neurons in the rabbit forebrain. The density of ChAT-immunoreactive terminals in layer V of distinct neocortical territories and in hippocampal subfields was also measured. Another cholinergic marker, the low-affinity neurotrophin receptor (p75(NTR)), was also employed to identify subsets of cholinergic neurons. Double-immunofluorescence labeling of ChAT and p75(NTR), calbindin D-28k (CB), parvalbumin, calretinin, neuronal nitric oxide synthase (nNOS), tyrosine hydroxylase, or substance P was used to elucidate the neuroanatomical borders of cholinergic nuclei and to analyze the neurochemical complexity of cholinergic cell populations. Cholinergic projection neurons with heterogeneous densities were found in the medial septum, vertical and horizontal diagonal bands of Broca, ventral pallidum, and magnocellular nucleus basalis (MBN)/substantia innominata (SI) complex; cholinergic interneurons were observed in the caudate nucleus, putamen, accumbens nucleus, and olfactory tubercule, whereas the globus pallidus was devoid of cholinergic nerve cells. Cholinergic interneurons were frequently present in the hippocampus and to a lesser extent in cerebral cortex. Cholinergic projection neurons, except those localized in SI, abundantly expressed p75(NTR), and a subset of cholinergic neurons in posterior MBN was immunoreactive for CB and nNOS. A strict laminar distribution pattern of cholinergic terminals was recorded both in the cerebral cortex and in CA1-CA3 and dentate gyrus of the hippocampus. In summary, the structural organization and chemoarchitecture of rabbit basal forebrain may be considered as a transition between that of rodents and that of primates.
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PMID:Rabbit forebrain cholinergic system: morphological characterization of nuclei and distribution of cholinergic terminals in the cerebral cortex and hippocampus. 1271 17

The anatomy of the inferior-collicular complex of the barn owl, situated below the fourth ventricle in the tectal lobe, was studied by determining the distribution of antigens with antibodies directed against tyrosine hydroxylase, gamma-aminobutyric acid (GABA)(Abeta), dopamine- and cyclic AMP-regulated phosphoprotein (DARPP-32), calretinin, and calbindin. Additionally, the somata were stained with cresyl violet, and fibers were marked according to the Gallyas procedure. These markers were chosen to allow for an easy delineation of the boundaries between the subnuclei of the inferior colliculus. We could discriminate eight structures that belong to the three subnuclei of the inferior colliculus [the central nucleus (ICC), the superficial nucleus (ICS), the external nucleus (ICX)] and to the optic tectum. Periventricular tectal layers 15a and 15b stained well with all the antibodies used. The ICS, embedded in tectal layer 15a, may be divided into a dorsal and a ventral lamina. It does not have direct contact with the other nuclei of the inferior colliculus. The border between tectal layer 15a and ICX was well marked by all antibodies, but less so in Gallyas and cresyl violet stains. The ICC consists of a core and a medial and lateral shell. The core was clearly demarcated with antibodies against calretinin and calbindin. The border between the lateral shell and the ICX was marked less well than the borders between ICX and 15a, but the somata were much more darkly labeled with the DARPP-32 antibody in ICX than in the lateral shell of ICC. None of the markers delineated the border between the medial and lateral shell of ICC.
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PMID:Anatomical markers for the subdivisions of the barn owl's inferior-collicular complex and adjacent peri- and subventricular structures. 1292 22

The cellular location and rhythmic expression of Period 1 (Per1) circadian clock gene were examined in the retina of a Per1::GFP transgenic mouse. Mouse Per1 (mPer1) RNA was localized to inner nuclear and ganglion cell layers but was absent in the outer nuclear (photoreceptor) layer. Green fluorescent protein (GFP), which was shown to colocalize with PER1 protein, was found in a few subtypes of amacrine neuron, including those containing tyrosine hydroxylase, calbindin, and calretinin, but not in cholinergic amacrine cells. A small subset of ganglion cells also contained GFP immunoreactivity (GFP-IR), but the melanopsin-containing subtype, which projects to the suprachiasmatic nuclei (SCN), lacked GFP-IR. Although the intensity of GFP-IR varied among the populations of amacrine cells at each time point that was examined, both diurnal and circadian rhythms were found for the fraction of neurons showing strong GFP-IR, with peak expression between Zeitgeber/circadian (ZT/CT) times 10 and 14. In SCNs that were examined in the same mice used for the retinal measures, the peak in GFP-IR also occurred at approximately ZT/CT 10. Our results are the first to demonstrate a circadian rhythm of a biological clock component in identified neurons of a mammalian retina.
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PMID:Cellular location and circadian rhythm of expression of the biological clock gene Period 1 in the mouse retina. 1293 Aug 6

Ground squirrel retinas were immunostained with antibodies against calcium binding proteins (CBPs) and classical neurotransmitters in order to describe neuronal phenotypes in a diurnal mammalian retina and to then compare these neurons with those of more commonly studied nocturnal retinas like cats' and rabbits'. Double immunostained tissue was examined by confocal microscopy using antibodies against the following: rhodopsin and the CBPs, calbindin, calretinin, parvalbumin, calmodulin and recoverin (CB, CR, PV, CM, RV), glycine, GABA, choline acetyltransferase (CHAT) and tyrosine hydroxylase (TOH). In ground squirrel retina, the traditional cholinergic mirror symmetric amacrine cells colocalize CHAT with PV and GABA and faintly with glycine. A second cholinergic amacrine cell type colocalizes glycine alone. CR is found in at least 3 different amacrine cell types. The CR-immunoreactive (IR) cell population is a mixture of glycinergic and GABAergic types. The dopamine cell type IR to tyrosine hydroxylase has the typical morphology of a wide field cell with dendrites in S1 but the "rings" seen in cat or rabbit retina are not as numerous. TOH-IR amacrine cells send large club-shaped processes to the outer plexiform layer. CB and CR are in bipolar cells, A- and B-type horizontal cells and several amacrine cell types. Anti-rhodopsin labels the low density rod photoreceptor population in this species. Anti-recoverin labels cones and some bipolar cells while PKC is found in several different bipolar cell types. One ganglion cell with dendritic branching in S3 is strongly CR-IR. We find no evidence for an AII amacrine cell in the ground squirrel, with either anti-CR or anti-PV. An amacrine cell with similarity to the DAP1-3 cell of rabbit is CR-IR and glycine-IR. We discuss this labeling pattern in relationship to other mammalian species. The differences in staining patterns and phenotypes revealed suggest a functional diversity in the populations of amacrine cells according to whether the retinas are rod or cone dominated.
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PMID:The neurons of the ground squirrel retina as revealed by immunostains for calcium binding proteins and neurotransmitters. 1450 Dec 5

We have studied the organization of the hypothalamus in an Australian diprotodontid metatherian mammal, the wallaby ( Macropus eugenii), using cytoarchitectural, histochemical and immunohistochemical techniques. Coronal sections of adult brains were processed for Nissl staining, histochemical reactivity (cytochrome oxidase, nicotinamide adenine dinucleotide phosphate diaphorase and acetylcholinesterase) and immunohistochemistry (antibodies to tyrosine hydroxylase, calbindin, calretinin, non-phosphorylated neurofilament protein, oxytocin and vasopressin). The distribution of immunoreactive neurons for these substances was mapped with the aid of a computer-linked microscope. In general, the wallaby hypothalamus showed a similar nuclear organization to that seen in rodents. The paraventricular nucleus could be divided into several subdivisions based on the different cellular parcellation, similar to that described in rodents. The ventromedial hypothalamic nucleus had cell-sparse dorsomedial and cell-dense ventrolateral subdivisions as seen in eutheria, suggesting a similar functional compartmentalization in all theria. The positions of tyrosine hydroxylase-positive neurons in the wallaby hypothalamus were also similar to those in eutheria. Oxytocin and vasopressinergic neurons were found in all the same major nuclear groups as seen in eutheria, although a nucleus circularis could not be identified. The general similarities between wallaby and eutherian hypothalamus indicate that the basic chemo- and cytoarchitectural features of the hypothalamus are common to eutheria and metatheria and validate the use of the wallaby as a mammalian model of wide applicability in investigations of hypothalamic functional development.
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PMID:Cyto- and chemoarchitecture of the hypothalamus of a wallaby ( Macropus eugenii) with special emphasis on oxytocin and vasopressinergic neurons. 1451 76

This study focused on the temporal and spatial pattern of expression of the cell adhesion molecule axonin-1 in amacrine cells and the identification of these cells in the developing chick retina. We analyzed 5-20-day-old chick embryos. The antigen was localized and visualized by the indirect immunogold and the immunofluorescence technique. Colocalization studies with antibodies against tyrosine hydroxylase, acetylcholinesterase, choline acetyltransferase, parvalbumin, calbindin, and calretinin served to characterize these cells further and to explore whether they have other properties in common. Axonin-1 was expressed in amacrine cells from E8 onward in the inner nuclear, in the inner plexiform, and in the ganglion cell layer. Their maturation showed a gradient similar to that found for amacrinogenesis. Expression was closely correlated with the period when the cells develop and shape their processes. The interneurons were classified with reference to Cajal, and most of the morphological types described by him were found. In addition, some cells were considered as axon-bearing amacrine cells. However, the total number of labeled cells was rather small. At least two morphologically different types terminated in each of the inner plexiform sublayers. Narrow- and wide-field arbors indicated the existence of a diversified network. The colocalization studies revealed that the neurotransmitters and neuropeptides overlapped partially with axonin-1 expression. This indicated that axonin-1-immunoreactive amacrine cells were also functionally diverse.
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PMID:Expression of axonin-1 in developing amacrine cells in the chick retina. 1468 82

We used immunohistochemical techniques to analyze the localization and distribution of the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) and the neuropeptides methionine-endephalin (M-Enk), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calretinin (Cal), calcitonin gene-related peptide (CGRP), substance P (SP), and galanin (Gal) in the stellate ganglia of two species of domestic animal (cattle and horses). NPY, VIP and Gal immunoreactive neurons (both cell body and nerve fiber) were observed in the stellate ganglia of both animals. M-Enk and CGRP immunoreactive nerve fibers were detected in the stellate ganglia of both animals, but positive cell bodies were found only in the stellate ganglia of the horse. In contrast, Cal- and SP-positive cell bodies existed in the stellate ganglia of cattle but not in the horse. SP-immunoreactive cells were observed only in young cattle. In both cattle and horses, almost all ganglion cell bodies exhibited TH immunoreactivity, but no positive nerve fibers were found.
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PMID:Neuropeptide distribution in the stellate ganglia of the domestic animal. 1497 66

The subventricular zone (SVZ) is a major neurogenic region in the adult brain. Cells from the SVZ give rise to two populations of olfactory bulb interneurons: the granule cells and periglomerular (PG) cells. Currently, little is known about the signaling pathways that direct these newly generated neurons to become either granule or PG neurons. In the present study, we used the nestin promoter and enhancer to direct expression of the tetracycline transactivator (tTA). We generated two independent strains of nestin-tTA transgenic animals and crossed founder mice from both lines to mice containing a tetracycline-regulated transgene (mCREB) whose expression served as a marker for the activity of the nestin-tTA transgene. mCREB expression occurred in a subset of proliferating cells in the SVZ and rostral migratory stream in both lines. Surprisingly, in both lines of nestin-tTA mice transgene expression in the olfactory bulb was limited to PG neurons and was absent from granule cells, suggesting that this nestin promoter construct differentiates between the two interneuronal populations. Transgene expression occurred in several subtypes of PG neurons, including those expressing calretinin, calbindin, GAD67, and tyrosine hydroxylase. These results suggest that a unique subset of SVZ precursor cells gives rise to PG, and not granule cells. The ability to express different transgenes within this subpopulation of neuronal precursors provides a powerful system to define the signals regulating the differentiation and survival of adult-generated neurons in the olfactory bulb.
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PMID:Nestin promoter/enhancer directs transgene expression to precursors of adult generated periglomerular neurons. 1517 89

The subventricular zone (SVZ) is known to be the major source of neural stem cells in the adult brain. In rodents and nonhuman primates, many neuroblasts generated in the SVZ migrate in chains along the rostral migratory stream (RMS) to populate the olfactory bulb (OB) with new granular and periglomerular interneurons. In order to know if such a phenomenon exists in the adult human brain, we applied single and double immunostaining procedures to olfactory bulbs obtained following brain necropsy in normal adult human subjects. Double immunofluorescence labelling with a confocal microscope served to visualize cells that express markers of proliferation and immature neuronal state as well as markers that are specific to olfactory interneurons. Newborn cells that express cell cycle proteins [Ki-67, proliferating cell nuclear antigen (PCNA)] were detected in the granular and glomerular layers (GLs) of the human olfactory bulb; these cells coexpressed markers of immature neuronal state, such as Doublecortin (DCX), NeuroD and Nestin. Numerous differentiating cells expressed molecular markers of early committed neurons [beta-tubulin class III (TuJ1)] and were also immunoreactive for glutamic acid decarboxylase (GAD), a marker of GABAergic neurons, or tyrosine hydroxylase (TH), a marker of dopaminergic neurons. Other early committed neurons expressed the calcium-binding proteins calretinin (CR) or parvalbumin (PV). These results provide strong evidence for the existence of adult neurogenesis in the human olfactory system. Despite its relatively small size compared to that in rodents and nonhuman primates, the olfactory bulb in humans appears to be populated, throughout life, by new granular and periglomerular neurons that express a wide variety of chemical phenotypes.
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PMID:Evidence of newly generated neurons in the human olfactory bulb. 1524 2


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