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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Substance P synaptic interactions with GABAergic and dopaminergic neurons in rat substantia nigra: an ultrastructural double-labeling immunocytochemical study. 137 84

The synaptic organization of the mediodorsal thalamic nucleus (MD) in the rat was studied with the electron microscope, and correlated with the termination of afferent fibers labeled with wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Presynaptic axon terminals were classified into four categories in MD on the basis of the size, synaptic vesicle morphology, and synaptic membrane specializations: 1) small axon terminals with round synaptic vesicles (SR), which made asymmetrical synaptic contacts predominantly with small dendritic shafts; 2) large axon terminals with round vesicles (LR), which established asymmetrical synaptic junctions mainly with large dendritic shafts; 3) small to medium axon terminals with pleomorphic vesicles (SMP), which formed symmetrical synaptic contacts with somata and small-diameter dendrites; 4) large axon terminals with pleomorphic vesicles (LP), which made symmetrical synaptic contacts with large dendritic shafts. Synaptic glomeruli were also identified in MD that contained either LR or LP terminals as the central presynaptic components. No presynaptic dendrites were identified. In order to identify terminals arising from different sources, injections of WGA-HRP were made into cortical and subcortical structures known to project to MD, including the prefrontal cortex, piriform cortex, amygdala, ventral pallidum and thalamic reticular nucleus. Axons from the amygdala formed LR terminals, while those from the prefrontal and insular cortex ended exclusively in SR terminals. Fibers labeled from the piriform cortex formed both LR and SR endings. Based on their morphology, all of these are presumed to be excitatory. In contrast, the axons from the ventral pallidum ended as LP terminals, and those from the thalamic reticular nucleus formed SMP terminals. Both are presumed to be inhibitory. At least some terminals from these sources have also been identified as GABAergic, based on double labeling with anterogradely transported WGA-HRP and glutamic acid decarboxylase (GAD) immunocytochemistry.
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PMID:Synaptic organization of projections from basal forebrain structures to the mediodorsal thalamic nucleus of the rat. 170 22

Knollenorgans, low-threshold electroreceptors found in mormyrid fish, are involved primarily, if not exclusively, in communication. The rhombencephalic nucleus of the lateral line lobe (nLLL) is the target nucleus of knollenorgan afferents. Cells in the nLLL receive a few medium size to large endings with round synaptic vesicles (classified as spoon; large club; small club-, and rodlet-shaped endings) with which they form nexus (gap junction) and asymmetrical chemical synapses associated with the round synaptic vesicles. In addition these endings emit thin collaterals which terminate as small boutons on nLLL neurons; these boutons also have round vesicles and make mixed (electrotonic and chemical) synapses. In addition, cells in the nLLL receive synaptic input from numerous small boutons containing pleomorphic vesicles and making symmetric synapses. We have not found any interneurons within nLLL. Our ultrastructural analysis suggests that boutons synapsing on nLLL neurons belong to only two afferent fiber systems and that the wiring diagram of nLLL is extremely simple. We have studied the immunolocalization in nLLL of glutamic acid decarboxylase (GAD), the enzyme essential for the synthesis of GABA that is also a useful marker for this widely distributed inhibitory neurotransmitter. GAD immunoreactivity was confined to the small boutons with pleomorphic vesicles. GAD was also found in a nucleus projecting to the nLLL, here named the sublemniscal nucleus (SL), which probably conveys corollary discharge signals to the nLLL. This GABAergic projection may be responsible for the potent inhibition associated with the electric organ discharge command that has been described in these cells.
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PMID:Cytology and immunocytochemistry of the nucleus of the lateral line lobe in the electric fish Gnathonemus petersii (Mormyridae): evidence suggesting that GABAergic synapses mediate an inhibitory corollary discharge. 285 Jun 19

Immunogold staining (IGS) for glutamic acid decarboxylase (GAD) was combined with the peroxidase-antiperoxidase (PAP) technique for tyrosine hydroxylase (TH) to analyze gamma-aminobutyric acid-catecholaminergic neuronal interactions in the rhesus hypothalamus. At the light-microscopic level, TH-immunoreactive (-IR) perikarya and their fibers (brown) were observed in the anterior ventral periventricular area (AVPV), the arcuate nucleus (ARC) and the adjacent periventricular zone (ARC-PVZ). GAD-IR processes (light red) were also present throughout the hypothalamus and appeared to contact some TH-IR neurons. At the electron-microscopic level, PAP was present in perikarya, dendrites, axons and axon terminals of TH-IR neurons. Colloidal gold particles (15 nm) were found only in dendrites and axon terminals of GAD-IR neurons. Labeled GAD terminals typically contained small, clear synaptic vesicles, while TH terminals contained these and sometimes one or two dense-core vesicles. In the ARC and ARC-PVZ, asymmetrical (Gray I) axodendritic synapses occurred between GAD and TH-IR profiles, with TH/GAD directionality more prevalent. Symmetrical (Gray II) synapses were less common, with either TH or GAD presynaptic in axodendritic and dendrodendritic contacts. GAD/GAD interactions were not observed, but TH/TH contacts appeared to be mostly dendrodendritic. In the AVPV, only symmetrical synapses were encountered, and their directionality was difficult to determine. GAD- and TH-IR dendrites frequently established dendrodendritic synapses, but GAD/TH dendrosomatic synapses were seldom seen. These results illustrate the complex interactions of GAD- and TH-containing elements in the neuroendocrine hypothalamus.
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PMID:GABAergic and catecholaminergic synaptic interactions in the macaque hypothalamus: double label immunostaining with peroxidase-antiperoxidase and colloidal gold. 287 51

GABAergic neurons have been identified in the piriform cortex of the opossum at light and electron microscopic levels by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase and by autoradiographic visualization of high-affinity 3H-GABA uptake. Four major neuron populations have been distinguished on the basis of soma size, shape, and segregation at specific depths and locations: large horizontal cells in layer Ia of the anterior piriform cortex, small globular cells with thin dendrites concentrated in layers Ib and II of the posterior piriform cortex, and multipolar and fusiform cells concentrated in the deep part of layer III in anterior and posterior parts of the piriform cortex and the subjacent endopiriform nucleus. All four populations were well visualized with both antisera, but the large layer Ia horizontal cells displayed only very light 3H-GABA uptake, thus suggesting a lack of local axon collaterals or lack of high-affinity GABA uptake sites. The large, ultrastructurally distinctive somata of layer Ia horizontal cells receive a very small number of symmetrical synapses; the thin, axonlike dendrites of small globular cells are exclusively postsynaptic and receive large numbers of both symmetrical and asymmetrical synapses, in contrast to somata which receive a small number of both types; and the deep multipolar and fusiform cells receive a highly variable number of symmetrical and asymmetrical synapses on somata and proximal dendrites. Labeled puncta of axon terminal dimensions were found in large numbers in the neuropil surrounding pyramidal cell somata in layer II and in the endopiriform nucleus. Moderately large numbers of labeled puncta were found in layer I at the depth of pyramidal cell apical dendrites with greater numbers in layer Ia at the depth of distal apical segments than in layer Ib. High-affinity GABA uptake was demonstrated in the termination zone of the projection from the anterior olfactory nucleus to the anterior piriform cortex. Cell bodies of origin of this projection displayed heavy retrograde labeling with 3H-GABA. Matching neuropil and cellular labeling was demonstrated with the GABA-BSA antiserum but not with the GAD antiserum, thus suggesting that GABA is normally present in these cells but is taken up from the neuropil rather than synthesized. No comparable high-affinity GABA uptake was demonstrated in the association fiber systems that originate in the piriform cortex.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Distribution and ultrastructure of neurons in opossum piriform cortex displaying immunoreactivity to GABA and GAD and high-affinity tritiated GABA uptake. 343 76

Glutamate (Glu) and gamma-aminobutyric acid (GABA) are the most abundant excitatory and inhibitory neurotransmitters in the mammalian hypothalamus. Glu and GABA-containing neurons have both been shown to synapse with gonadotropin-releasing hormone (GnRH) and other neuroendocrine systems in the hypothalamus of several species. Since their direct interactions could play a pivotal role in governing neuroendocrine function, we performed double-label immunostaining for Glu and for glutamic acid decarboxylase (GAD) as a marker for GABAergic neurons in hypothalamic sections from adult female cynomolgus monkeys. Ultrastructural analysis of 785 Glu-immunoreactive (-ir) and GAD-ir elements in the medial septum (MS), arcuate nucleus-ventral hypothalamic tract (VHT1), supraoptic nucleus (SON), paraventricular nucleus (PVN), and median eminence (ME) revealed that 63% were Glu-ir, 28% were GAD-ir, and 9% were Glu + GAD-ir. In addition, we observed surprisingly consistent labeling of 2-4% somata (SOM), 65-80% dendrites (DEN), and 15-30% axons and terminals (AXO) in all of these areas. Characterization of 177 interactions (36% synapses, 64% contacts) by pre/post-transmitter content indicated that 29% contained Glu/GAD, 15% Glu/Glu, and 15% Glu/Glu + GAD, while 16% were unlabeled/Glu, 9% were unlabeled/GAD, and 16% expressed other transmitter combinations. Regional analysis of these interactions showed that 43% occurred in the MS, 22% in VHT1, 14% in SON, 9% in PVN, and 12% in the ME. AXO/DEN interactions made up 51% of all labeled interactions characterized, and were comprised 29% of Glu/GAD, 22% of Glu/Glu, and 18% of the Glu/Glu, and 18% of the Glu/Glu + GAD type. AXO/DEN synapses were more prevalent than contacts in all areas except the PVN and of course the ME, where anatomical synapses do not occur. AXO/SOM interactions represented approximately 15% of all those identified, and were predominantly unlabeled/Glu (71%) and unlabeled/GAD (18%) synapses. Almost all (95%) AXO/SOM synapses and 75% of the contacts occurred in the MS. DEN/DEN interactions, 28% of the total, were composed 50% of Glu/GAD, 12% of Glu/Glu, and 18% of the Glu/Glu+GAD type. The relatively few DEN/DEN synapses all appeared in the MS, whereas much more abundant DEN/DEN contacts were more widely distributed. DEN/SOM interactions, 6% of the total, appeared only as contacts, with the majority (60%) again located in the MS. In addition, the MS contained 48% of all asymmetrical synapses (vs. 35% in VHT1 and 17% in SON), 62% of all symmetrical synapses (vs. 19% in VHT1 and 14% in SON), and 35% of all contacts (vs. 21% in VHT1 and 12% in SON) identified.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Glutamate and GABAergic neurointeractions in the monkey hypothalamus: a quantitative immunomorphological study. 761 24

Synaptic contacts between noradrenaline (NA) neurons and GABA (gamma-aminobutyric acid) afferents and/or substance P (SP) afferents in the locus coeruleus (LC) were examined by a combination of immunoelectron microscopic mirror method and double-immunostaining method. For visualization of NA and GABA, we used antibodies against NA and GABA synthesizing enzymes, i.e., tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD). GAD-immunoreactive (IR) and SP-IR axon terminals often made synaptic contacts with NA neurons, respectively. Furthermore, we identified that a single NA neuron simultaneously receives synaptic inputs from GAD-IR and SP-IR afferents. These NA neurons made symmetrical synaptic contacts with GAD-IR axon terminals and asymmetrical contacts with SP-IR axon terminals. This suggests that central NA neuronal mechanisms are affected by GABA and SP neurons in a different manner.
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PMID:GABA-ergic and substance P-ergic double-innervation to noradrenergic neurons in the rat locus coeruleus. 930 37

We have recently revealed that large multipolar neurons, presumed mossy cells in the hamster dentate gyrus (DG), were calretinin (CR)-immunoreactive (IR) at the ventral level, although these neurons were CR-negative at the dorsal level. In the present study, we confirmed this identification with several methods and analyzed structural features of hamster mossy cells in detail. Golgi impregnationi and intracellular Lucifer yellow labeling studies revealed that mossy cells in the hamster dentate hilus had extraordinarily prominent thorny excrescences on their somata as well as on their proximal dendrites. Mossy cells exhibited dorsoventral differences in their structural features; proximal dendrites of single mossy cells were fewer, and thorny excrescences were larger and more complicated at the dorsal level than at the ventral level. Electron microscopic serial section three-dimensional reconstructions revealed that somatic thorny excrescences consisted of large and complicated spines, which received numerous asymmetrical synapses from mossy fiber terminals. In addition, our confocal laser scanning microscopic observations also revealed many glutamic acid decarboxylase-immunoreactive punctae abutting the mossy cell somata and dendrites. Our present and previous observations revealed the structural features of hamster mossy cells and their differences along the dorsoventral axis and further indicated that mossy cells were prominently different in their chemical and morphological features among species.
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PMID:Structural features of mossy cells in the hamster dentate gyrus, with special reference to somatic thorny excrescences. 1108 93

We revealed the structural features of particular synaptic regions, nidi, and newly found neurons, tasseled cells, in the main olfactory bulb (MOB) of the laboratory musk shrew (Suncus murinus). Nidi were intensely immunoreactive for glutamic acid decarboxylase (GAD) and calbindin D28k (CB), were 30-80 microm in diameter, and were located beneath glomeruli, appearing to make glomerulus-nidus unit-like complexes. In contrast to glomeruli, they contained few or no olfactory nerves. Nidi were distributed throughout the whole MOB and made a distinctive layer, nidal layer. Tasseled cells were located in the mitral cell layer and in the middle of the external plexiform layer (EPL) and extended single primary dendrites to the nidus, where their small tuft-like complicated branches intermingled with processes of perinidal cells surrounding nidi. Primary dendrites of mitral/tufted cells also penetrated nidi but passed to glomeruli. In the outer half of the EPL, columnar structures were seen, where CB- and GAD-positive elements appeared to associate with bundles of cylindrical dendrites of presumed mitral/tufted and tasseled cells. By electron microscopic examinations, nidi were confirmed to be particular synaptic areas where GAD-positive processes made symmetrical synapses to GAD-negative presumed tasseled and mitral/tufted cell dendrites and received asymmetrical synapses from the latter. Retrograde tracings revealed that tasseled cells, in addition to mitral/tufted cells, projected their axons to the lateral olfactory tract, indicating that there were two parallel projection systems in the shrew MOB, which might interact with each other via various types of gamma-aminobutyric acid (GABA)ergic interneurons. The present study clearly showed that the neuronal organization of the shrew MOB was distinctly different from that in rodents.
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PMID:Nidus and tasseled cell: distinctive neuronal organization of the main olfactory bulb of the laboratory musk shrew (Suncus murinus). 1116 86

Previously, several studies attempting to analyze olfactory functions using dissociated culture systems of the olfactory bulb (OB) have been reported. Reciprocal dendrodendritic synapses between secondary neurons (mitral/tufted cells) and interneurons (periglomerular/granule cells) are considered to play the most important role in signal processing in the OB. However, it is unclear whether these reciprocal synapses are formed in vitro in the same way as they are in the intact OB. Thus, we synaptologically investigated the nature of cultured OB neurons. These neurons from embryonic rats were classified into four groups based on the size of their somata and their glutamic acid decarboxylase (GAD) immunoreactivity. At 14 days in vitro, most of the neurons synchronously showed spontaneous intracellular Ca2+ oscillations that were reversibly inhibited by application of D-APV and CNQX. Moreover, the frequency of the oscillations decreased and their amplitude became larger following application of bicuculline. These results suggest functional glutamatergic synaptic coupling and inhibitory GABAergic synaptic modulation. Immunocytochemical staining revealed many dot-like products (puncta) that were immunoreactive to GAD as well as to synaptophysin surrounding the cultured neurons. These results strongly indicate the presence of GABAergic synapses. The existence of synaptic contacts in OB neuron cultures was also confirmed by electron microscopy. Two types of synapses, symmetrical and asymmetrical, were morphologically recognizable. Moreover, we could also identify peculiar synapses resembling the in vivo reciprocal dendrodendritic synapses. The use of these primary culture systems will facilitate the elucidation of mechanisms underlying olfactory functions.
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PMID:A primary culture system of rat olfactory bulb forming many synapses similar to intact ones and spontaneously generating synchronous intracellular calcium oscillations. 1119 91


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