Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was designed to investigate the existence of two key enzymes involved in the metabolism of gamma-aminobutyric acid, glutamic acid decarboxylase (GAD) and glutamine synthetase (GS), in the area postrema (AP) of the cat. The results showed that punctuate structures of variable size corresponding to axon terminals, exhibited GAD-immunoreactivity and were distributed in varying densities. The greatest accumulation was present in the caudal and middle segment of the AP and particularly in the area subpostrema, where the aggregation of terminals was extremely dense. The population of the GAD-labelled axon profiles gradually decreased toward the solitary complex. No neuronal bodies were labelled in our preparations. The electron microscopic studies revealed a large variety of contacts between labelled terminals and unlabelled dendrites, axons or neurons. The possibility that the GAD-immunoreactive terminals might correspond to vagal afferent projections was discussed on the basis of our observations and of other studies that employed horseradish peroxidase or degeneration methods. GS-immunoreactivity was seen in ependymoglial cells of the AP, particularly toward the caudal region, and in astrocytes and their processes of the AP proper. The latter were frequently observed around capillaries. The presence of both GAD-immunoreactive profiles and GS-immunostained ependymoglial cells and astrocytes in the AP, provided further immunocytochemical evidence of the functional correlation between the two enzymes.
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PMID:Immunocytochemical localization of glutamic acid decarboxylase (GAD) and glutamine synthetase (GS) in the area postrema of the cat. Light and electron microscopy. 288 70

Chandelier cell axons were studied in the sensory-motor cortex of adult monkeys. The axonal fields of Golgi-impregnated chandelier cells in layer II in motor cortex are flattened sagittally. The vertical terminal portions of the axons varied both in length and in the numbers converging to form terminations of greater or lesser complexity. Golgi-impregnated plexuses were embedded in plastic and resectioned serially at 2.5-3.0 micrograms. A single axonal field could have as many as 400 terminal rows. All lie 3-13 micrograms beneath pyramidal cell somata. These terminations are not randomly distributed but instead, form clusters. Further resectioning the plastic sections for electron microscopy revealed that all the terminations are on the initial axon segments of pyramidal cells and all form symmetric synaptic contacts. In immunocytochemical material stained for glutamic acid decarboxylase (GAD), the enzyme involved in the synthesis of GABA, GAD-positive boutons were found to form symmetric synaptic contacts with a variety of postsynaptic elements including the axon hillocks and axon initial segments of pyramidal cells. Serial reconstructions from electron micrographs revealed GAD-positive terminals synapsing with the axon initial segment of pyramidal cells joined by cytoplasmic bridges and forming vertically oriented rows identical to those of chandelier cell terminals identified positively in the resectioned Golgi material. The GAD-positive terminals forming initial segment synapses were never continuous with GAD-positive terminals forming axo hillock synapses. The latter probably arise from basket cell axons. Initial segments of pyramidal cell axons in layers II and III were contacted by more GAD-positive terminals than the initial segments of pyramidal cell axons in layer V. The largest pyramidal cells in layer III received the most synapses. Many larger pyramidal cells, identified as callosally projecting cells by the retrograde transport of horseradish peroxidase (HRP), were shown in serial electron micrographs to possess large numbers of initial segment synapses, comparable to those seen in the immunocytochemical material. Serial reconstructions of pyramidal cell axons from axon hillock to the first myelin internode in resectioned Golgi, immunocytochemical and HRP material showed that the number of synapses varied from 2 to 52 for layers II and III and from 2 to 26 for layer V. The number of synapses on the axon hillocks varied from zero to 12. The variability in these terminations may be an important factor in the shaping of the functional properties of the pyramidal cells.
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PMID:Variability in the terminations of GABAergic chandelier cell axons on initial segments of pyramidal cell axons in the monkey sensory-motor cortex. 298 7

Previous cytoarchitectural and electron micrographic studies have indicated that the gustatory zone of the nucleus of the solitary tract (NST) may contain local circuit neurons. It is known that neurons of the caudal "visceroceptive" NST contain GABA, glutamic acid decarboxylase (EC 4.1.1.15), and GABA-transaminase (GABA-T; 4-aminobutyrate: 2-oxoglutarate aminotransferase; EC 2.6.1.19). The present study was conducted to determine whether or not neurons in the gustatory zone of the NST of rat contain GABA and the principle degradative enzyme of GABA, GABA-T. Transganglionic transport of horseradish peroxidase (HRP) was used to identify chorda tympani (CT) nerve terminal fields. Immunohistochemical studies were combined with transport experiments to evaluate the organization of GABA immunoreactive neurons in CT terminal fields. Results show that GABA immunoreactive neurons and puncta are located within CT terminal fields. These neurons evince small ovoid morphologies resembling Golgi interneurons, and comprise an average of 18% of total neurons in CT terminal fields. Independent histochemical studies reveal that approximately 82% of GABA immunoreactive neurons within CT terminal fields exhibit GABA-T activity. Retrograde transport of HRP was used in additional studies to evaluate whether or not axons of putative GABAergic neurons project to the second-order central gustatory relay located in the caudal parabrachial nucleus (PBNc), to the caudal NST, or to regions surrounding the rostral or caudal NST. Combined studies indicate that GABA immunoreactive neurons in the gustatory NST do not project axons to the PBNc, to the caudal NST, or to regions adjacent to the rostral or caudal NST.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Organization of GABA and GABA-transaminase containing neurons in the gustatory zone of the nucleus of the solitary tract. 320 50

Quetol 651 was used as an embedding medium for the demonstration of gamma aminobutyric acid (GABA) in semithin sections by the peroxidase-anti-peroxidase method. In order to demonstrate the immunoreactivity, the embedding medium was partially dissolved using absolute ethanol containing 0.8-1 M NaOH or KOH for 5-7 min. The experimental procedure was elaborated by testing the GABAergic sites in the endings surrounding the small neurones of the anterior exterolateral nucleus of a mormyrid fish and in the pyramidal cells of the electrosensory lateral line lobe of gymnotoid fish by applying anti-GAD (glutamic acid decarboxylase) antiserum. To test the general validity of the use of Quetol 651, GABAergic sites were also identified in the central nervous system of an insect, the honey bee, with anti-GABA and anti-GAD antisera. The intensity of labelling revealed by immunoperoxidase applied to Quetol 651-embedded semithin sections, demonstrated high precision and gave good resolution for light microscopical observations.
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PMID:The use of Quetol 651 for the post-embedding immunohistochemical demonstration of gamma-aminobutyric acid on semithin sections. 320 22

This is a study of the form, density, and distribution of glutamic acid decarboxylase (GAD) immunoreactive neurons and puncta (axon terminals) in the adult rat medial geniculate complex. GAD-positive elements were stained by either the peroxidase-antiperoxidase or avidin-biotin procedures. Thalamic architectonic subdivisions were defined independently in Golgi, Nissl, plastic-embedded semi-thin, and fiber-stained preparations, and from investigations of medial geniculate connectivity. GAD-positive neurons represent only approximately 1% of medial geniculate neurons. They occur in the three major medial geniculate subdivisions (ventral, dorsal, and medial). There is variability between subdivisions in the form and number of such neurons, and among the puncta. In the ventral division, immunopositive somata may have sparsely branched dendrites as long as 300-400 microns and capped with varicose expansions or bouton-like sprays of appendages. These closely appose the somata or primary dendrites of other cells; the axons of these GAD-positive neurons are also immunostained. In the dorsal division there are fewer GAD-positive neurons and their structure is different. Their dendrites are rarely immunoreactive for more than 100-150 microns; nor can their immunostained axons be traced very far. In the medial division the number of GAD-positive neurons, considering the relatively small size of this division, was high. These neurons rarely have immunostained dendrites, and more than one type of neuron is immunoreactive. The average somatic diameter of GAD-positive neurons is about 60% of that of non-immunostained cells in semi-thin material; however, the range of somatic area and the dendritic variability of these neurons suggest that cells representing more than one population are immunopositive and include all but the largest neurons. The puncta also show regional differences. Small (0.5-2 microns in diameter), medium (2-3 microns), or large (greater than 3 microns) puncta occur. In the ventral division, the predominantly medium-sized puncta are about four times as numerous on a unit/area basis than in the dorsal division, where they are far smaller and more delicate; medial division puncta are as numerous as those in the ventral division, but are much larger and coarser, and may form perisomatic arrangements. Controls were devoid of specific immunostaining.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Anatomy of glutamic acid decarboxylase immunoreactive neurons and axons in the rat medial geniculate body. 320 52

The ultrastructure, afferent input, and sites of termination of neurons containing neuropeptide Y-like immunoreactivity (NPY-LI) were examined in the adult rat nucleus accumbens by using the peroxidase-antiperoxidase (PAP) method. The NPY-LI was seen in sparsely distributed, spindle-shaped perikarya having cross-sectional diameters of 15-20 microns. These perikarya exhibited highly invaginated nuclear membranes and thin rims of cytoplasm containing Golgi lamellae, dense-core vesicles, and other organelles. A few large, principally aspiny, dendrites also showed NPY-LI. The dendrites received synaptic input from unlabeled terminals forming both symmetric and asymmetric junctions. Immunolabeling for NPY was evident in other processes that were not clearly differentiated as dendrites or axons. These were seen primarily near glial processes and the basal laminae of blood vessels. A few myelinated and many unmyelinated axons and axon terminals also were labeled for NPY. These terminals contained numerous, small (40-60 nm), clear and one or more large (80-100 nm) dense core vesicles. Forty-seven percent (27 out of 57) of the terminals containing NPY-LI formed symmetric junctions with unlabeled dendrites or dendritic spines. The remainder lacked recognizable densities within single planes of section. The neurons exhibiting NPY-LI in the nucleus accumbens were characterized further with respect to their afferent input from terminals labeled for the GABA-synthesizing enzyme, glutamic acid decarboxylase (GAD). Immunogold labeling of a rabbit antiserum against NPY and PAP labeling for a sheep antiserum to GAD were sequentially applied to the same sections. The GAD-labeled terminals formed symmetric junctions primarily with the more numerous unlabeled dendrites. However, a few synaptic junctions also were detected between the GAD-labeled terminals and dendrites showing immunogold labeling for NPY. We conclude (1) that in the rat nucleus accumbens, NPY-LI is found principally in neurons of the aspiny type and (2) that the output from these presumably intrinsic neurons to other neighboring neurons or blood vessels is at least partially modulated by GABA.
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PMID:Neuropeptide Y in the rat nucleus accumbens: ultrastructural localization in aspiny neurons receiving synaptic input from GABAergic terminals. 336 92

The coexistence of immunoreactivities for choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) and/or gamma-aminobutyric acid (GABA) was revealed in some brain regions of the rat, using the peroxidase-antiperoxidase method. Consecutive 40 micron thick vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning so as to be included at the paired surfaces of two adjacent sections were identified. The coexistence of the immunoreactivities for ChAT and GAD or GABA in the same cell could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. In the retina, cerebral cortex, basal forebrain and spinal cord, colocalization of ChAT-like and GAD-like or GABA-like immunoreactivities was observed in some cell types, whereas no such colocalization was observed in cells in the striatum or brainstem. In the retina, the majority of ChAT-like immunoreactive (ChAT-LI) amacrine cells contained GABA-like or GAD-like immunoreactivity. About half of the ChAT-LI neurons in the cerebral cortex showed GABA-like immunoreactivity. In the basal forebrain only a small proportion of ChAT-LI neurons (0.6%) contained GAD-like immunoreactivity. In the spinal cord, about one-third of ChAT-LI central canal cluster cells and about half of ChAT-LI dorsal horn cells showed GAD-like and/or GABA-like immunoreactivities. These observations indicate the possible coexistence of two classical transmitters, GABA and acetylcholine, in various brain regions and spinal cord of the rat.
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PMID:Cholinergic neurons containing GABA-like and/or glutamic acid decarboxylase-like immunoreactivities in various brain regions of the rat. 338 59

Synaptic interactions between striatal projection neurons and axon terminals containing immunoreactive glutamic acid decarboxylase (GAD) or Leu-enkephalin were examined in the rat neostriatum using a combined method of horseradish peroxidase retrograde transport from the substantia nigra and immunohistochemistry at the electron microscopic level. Results showed that numerous immunoreactive GAD and enkephalin boutons formed synapses with the cell bodies and dendrites of medium-sized striatonigral neurons. These findings demonstrate that within the neostriatum GABA and enkephalin directly influence caudate output pathways.
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PMID:Glutamic acid decarboxylase and enkephalin immunoreactive axon terminals in the rat neostriatum synapse with striatonigral neurons. 351 36

Amygdalopetal cholinergic neurons in the ventral pallidum were identified by combining choline acetyltransferase (ChAT) immunohistochemistry with retrograde tracing of horseradish peroxidase (HRP) following injections of the tracer in the basolateral amygdaloid nucleus. Although ChAT-positive terminals were identified in the ventral pallidum, they were never seen in contact with either immunonegative or ChAT-positive amygdalopetal neurons. In material, in which immunostaining against glutamic acid decarboxylase (GAD), the synthesizing enzyme for GABA was combined with retrograde tracing of HRP from the basolateral amygdaloid nucleus, GAD-positive terminals were seen to contact immunonegative amygdalopetal neurons. In addition, when sections of the rostral forebrain were processed, first to preserve and identify the transported HRP, and then were sequentially tested for both ChAT and GAD immunohistochemistry with the immunoperoxidase reaction for both tissue antigens, GAD-immunopositive terminals were seen to make synaptic contacts with cholinergic amygdalopetal neurons. These results suggest that amygdalopetal, presumably cholinergic, neurons receive GAD-positive terminals. In separate experiments using immunoperoxidase for ChAT and ferritin-avidin for GAD labeling, we confirmed the presence of GAD-containing terminals on cholinergic neurons. In addition, cholinergic terminals were seen in synaptic contact with GAD-positive cell bodies. These morphological studies suggest that direct GABAergic-cholinergic and cholinergic-GABAergic interactions take place in the rostral forebrain.
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PMID:GABAergic input to cholinergic forebrain neurons: an ultrastructural study using retrograde tracing of HRP and double immunolabeling. 352 37

Postembedding immunocytochemistry with a gamma-aminobutyric acid (GABA) antiserum was done on semithin sections of cat lateral geniculate nucleus (LGN) previously processed with the rapid-Golgi and gold-toning procedures, to determine which of the three main morphological types (1, 2,3) of neurons in the A-laminae show immunoreactivity and are, therefore, presumably GABAergic. Only type 3 cells were found to be GABA positive. These cells were characterized by small somata and few, scarcely branched dendrites bearing almost exclusively appendages with long slender stalks. Some of these cells have extensive filiform "axonlike" processes originating from different regions of dendrites and having appendages similar to those originating directly from dendrites. Many of these Golgi gold-toned impregnated dendritic appendages of type 3 cells were analyzed in the electron microscope and were identified as typical F2 terminals by their content of pleomorphic synaptic vesicles; by being postsynaptic to retinal (RLP), cortical (RSD), and perigeniculate (F1) terminals; and by being presynaptic to dendrites. In addition, since it was previously demonstrated that glutamic acid decarboxylase (GAD) and GABA-positive cells are not retrogradely labeled with horseradish peroxidase (HRP) from the visual cortex, the present results, by showing that GABA-positive cells have type 3 morphology, provide supporting evidence for the interneuronal nature of type 3 cells in cat LGN.
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PMID:Localization of gamma-aminobutyric acid (GABA) in type 3 cells and demonstration of their source to F2 terminals in the cat lateral geniculate nucleus: a Golgi-electron-microscopic GABA-immunocytochemical study. 354 41


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