Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One type of striatonigral neuron in the rat has been characterized. Golgi impregnation of striatal neurons that had been retrogradely labeled by horseradish peroxidase has shown that the medium-sized, densely spiny neurons project to the substantia nigra. Some of the synapses on three of these identified striatonigral neurons have been studied in the electron microscope following replacement of the Golgi deposit by means of the 'gold-toning' method. Synapsing axonal boutons were found on the following sites: soma and axon initial segment (symmetrical, with flattened or pleomorphic vesicles); primary and secondary dendritic shafts (symmetrical with pleomorphic vesicles); dendritic spines (asymmetrical, with spheroidal vesicles). These findings show that new information concerning neuronal connectivity can be obtained by combining three classical procedures in the same material: first, the Golgi method, that characterizes the type of neuron on the basis of its dendritic morphology; second, a retrograde tracing method, that identifies the projection area of the neuron; and, third, ultrastructural analysis of the nature of afferent terminals on the neuron.
 ...
PMID:Projection of neostriatal spiny neurons to the substantia nigra. Application of a combined Golgi-staining and horseradish peroxidase transport procedure at both light and electron microscopic levels. 9 16

The peripheral membrane protein fraction released by washing Acholeplasma laidlawii membranes with low-ionic strength buffers contained about 50% of the total membrane-bound ribonuclease and deoxyribonuclease activities. The ATPase, NADH oxidase and p-nitrophenylphosphatase activities remained bound to the membrane even when EDTA was added to the wash fluids, and thus appear to belong to the integral membrane protein group. Serving as a marker for peripheral membrane proteins, the membrane-bound ribonuclease activity was solubilized by bile salts much more effectively than the integral membrane-bound enzymes. On the other hand, the solubilized ribonuclease showed a much lower capacity to reaggregate with other solubilized membrane components to membranous structures. Yet, most of the ribonuclease molecules which were bound to the reaggregated membranes could not be released by low-ionic strength buffer. The reaggregated membranes differed from the native membranes in the absence of particles on their fracture faces obtained by freeze cleaving, and by their much higher labeling by the [125-I]lactoperoxidase iodination system. These results suggest that most of the proteins are exposed on the reaggregated membrane surfaces, with very little, if any, protein embedded in its lipid bilayer core. Enzyme disposition in the A. laidlawii membrane was studied by comparing the activity of isolated membranes with that of membranes of intact cells after treatment with pronase or with an antiserum to membranes. The data indicate the asymmetrical disposition of these activities, the ATPase and NADH oxidase being localized on the inner membrane surface, while the nucleases are exposed on the external membrane surface.
 ...
PMID:Characterization of the mycoplasma membrane proteins. V. Release and localization of membrane-bound enzymes in Acholeplasma laidlawii. 23 52

Synaptic junctions located on the dendrites of lamprey (Petromyzon marinus) reticulospinal neurons labelled with intracellularly-injected horseradish peroxidase were studied. The normal ultrastructure of the synaptic junctions was defined and several quantitative measures made from each junction in order to test the hypothesis that distally-located synapses are ultrastructurally different from those located at proximal dendritic sites. A total of 820 contacts from one neuron and 279 from a second neuron ranging from 20 to 340 microns from the soma were quantified. The vast majority of the presynaptic endings contained round, clear-cored vesicles and formed an asymmetrical membrane differentiation with the postsynaptic dendrite. A small fraction of the population contained flattened or pleomorphic vesicles and these synapses were equally distributed with respect to distance from the soma. Many of the terminals contained a few large dark- and clear-cored vesicles. Four quantitative measures of each synaptic contact were made. These included vesicle number, length of differentiated membrane, vesicle area and terminal area. Four ratios relating the different quantitative measures were also calculated. Each ratio or measurement from the synaptic junctions was plotted as a function of distance from the soma to determine if differences existed at any distance. It was found that synaptic junctions are uniformly similar and that distal junctions did not differ significantly (P greater than 0.05) from those at proximal dendritic sites. It is concluded that if distal synapses do compensate for their remote location they do this is some other way, possibly by increasing the number of synaptic contacts made by each presynaptic axon.
 ...
PMID:The relationship between some measures of synaptic ultrastructure as a function of distance from the soma on lamprey reticulospinal neurons. 54 91

Anatomical and electrophysiological methods were used to investigate the projections and response properties of neurons in the second cervical (C2) spinal segment of the cat giving origin to a previously undescribed projection to the ipsilateral thalamus. The method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify neurons in C2 giving rise to thalamic projections. Following large (3.0 microliter) thalamic HRP injections, a large number of labeled neurons was observed in lateral laminae VII-VIII of C2 ipsilateral to the injections. They occurred as small clusters of cells along the longitudinal axis of C2. Labeled neurons were also observed contralaterally in the lateral cervical nucleus, dorsal horn (especially medial lamina VI), and loosely distributed in the ventral horn. The ipsilaterally projecting neurons were also labeled following small (0.2--0.5 microliter) HRP injections restricted to individual spinothalamic terminal zones (intralaminar nuclei, ventrobasal complex-nucleus ventralis lateralis border zone, medial division of the posterior nuclei), indicating that as a group they project widely throughout the thalamus. Single unit recording methods were used to obtain complementary information on the functional properties of these neurons. The antidromic stimulation method was applied to identify units in C2 projecting to the ipsilateral thalamus in anesthetized, paralyzed cats. Three categories of ipsilaterally projecting C2 units were identified: (1) units not driven by any type of natural stimulation; (2) units having large cutaneous receptive fields (RFs) and wide dynamic response ranges ("widefield"), and (3) units with smaller RFs and varied properties ("other"). Widefield units with bilaterally symmetrical and asymmetrical RFs were observed. Co-stimulation of different portions of an excitatory RF produced summation of the unit response. Inhibitory RF components were identified in one-third of the widefield units. Unit recordings after spinal tract lesions revealed that the afferent input passed via the ipsilateral lateral and/or ventral funiculi. Widefield unit responses to somatosensory stimuli could be inhibited by dorsal column conditioning stimulation. Several "other" units resembled widefield units, while a second group had small RFs restricted to the C2 dermatome. Possible functional roles of the projecting C2 neurons in somatosensory and non-specific systems are discussed.
 ...
PMID:Anatomical and physiological properties of ipsilaterally projecting spinothalamic neurons in the second cervical segment of the cat's spinal cord. 70 88

Four spinocervical tract cells in lumbosacral spinal cords of adult cats were physiologically characterized and intracellularly labelled with horseradish peroxidase. The neurones were examined with a light microscope and reconstructed. Selected regions were chosen for ultrastructural analysis. Thin sections were treated to reveal the presence of L-glutamate by using the postembedding immunogold method. Two antisera, which specifically recognise the presence of fixed glutamate in tissue, were used in the study. Somata, proximal, and distal dendrites of all four neurones received synaptic contacts from boutons which displayed an obvious immunogold reaction. These boutons formed between 35% and 48% of all synaptic contacts onto spinocervical tract cells. Glutamate-enriched boutons were associated with gold particle densities which were 2-3 times greater than the average densities associated with the surrounding neuropil. Their profiles had a mean diameter of 1.68 microns, contained round agranular synaptic vesicles, and formed asymmetrical synaptic junctions. However, not all boutons displaying these characteristics were enriched with glutamate. Immunogold studies of alternate thin sections, which were incubated with glutamate or GABA antiserum, demonstrated that synaptic boutons on spinocervical tract cells were either enriched with GABA or with glutamate and formed two separate populations which had distinct morphological characteristics. GABA-containing boutons contained irregularly shaped agranular vesicles and formed symmetrical synaptic junctions, whereas glutamate-enriched boutons corresponded to those described above. A further population of boutons, containing highly flattened vesicles, was not immunoreactive for GABA or glutamate. The evidence supports the idea that much of the excitatory transmission into the SCT is mediated by L-glutamate.
 ...
PMID:Direct observations of synapses between L-glutamate-immunoreactive boutons and identified spinocervical tract neurones in the spinal cord of the cat. 136 31

The efferent projections of the medial geniculate nucleus (MG) and its adjacent nuclei to the basal ganglia were studied in the rat by the antero- and retrograde tracing methods. Injections of wheat germ agglutinin conjugated to horseradish peroxidase into the caudal parts of the striatum and globus pallidus produced retrograde neuronal labeling in the medial division of the MG (MGm) and its adjacent structures including the suprageniculate, posterior intralaminar and peripeduncular nuclei, and substantia nigra pars lateralis. Injections of [3H]leucine into the MG and its surroundings resulted in anterograde labeling not only in the striatum but also in the globus pallidus. The resulting labeling was distributed exclusively in the caudal parts of these two nuclei. The electron microscopic autoradiography showed preferential radiolabeling of terminals and myelinated axons in both the globus pallidus and striatum. Labeled terminals in the pallidum mostly made symmetrical synapses on somata and major dendrites, while labeled terminals in the striatum established asymmetrical synapses on dendritic spines. These morphological differences in the synapses of the efferent systems originating from the MGm and its surrounding region suggest functional/chemical differentiations at their target sites in the basal ganglia.
 ...
PMID:Ultrastructural morphology of projections from the medial geniculate nucleus and its adjacent region to the basal ganglia. 138 84

Combined injections of ibotenic acid and horseradish peroxidase (HRP) were made into the region of the mouse ventrobasal thalamus that is related to the large mystacial vibrissae. Examination 4 and 5 days later of the corresponding area of the primary somatosensory cortex (i.e., barrel cortex), in thick and in thin sections, showed it to contain numerous corticothalamic projection cells the somata, dendrites and axons of which were densely labeled by the retrograde transport of HRP. Analysis of serial thin sections showed that thalamocortical axon terminals, which had degenerated in response to the injection of ibotenic acid, formed approximately 20% of the asymmetrical synapses in barrel cortex. The fine structure and distribution in cortex of degenerating thalamocortical axon terminals and of intrinsic HRP-labeled corticothalamic axon terminals were identical to those reported in previous studies in which the injection of HRP into the thalamus was combined with the making of electrolytic lesions. This indicates that injecting ibotenic acid is an effective replacement for electrolytic lesioning of the thalamus. The combined injection of ibotenic acid and HRP represents a new and efficient approach for studying reciprocal projection pathways.
 ...
PMID:A simplified approach to retrograde/anterograde axonal labeling using combined injections of horseradish peroxidase and ibotenic acid. 140 32

The cortex projects heavily to the striatum and makes asymmetrical synaptic contact mainly with the spines of medium-sized densely spiny neurones. The possibility exists that corticostriatal terminals also make synaptic contact with classes of striatal interneurones. The primary objective of the present experiment was to determine whether parvalbumin-immunoreactive neurones, which represent a class of GABAergic interneurones in the striatum, also receive a direct synaptic input from corticostriatal fibres. The anterograde tracer biocytin was injected into the motor and premotor cortices of the squirrel monkey (Saimiri sciureus). Following perfuse-fixation, sections of the striatum were processed histochemically to reveal the transported biocytin using an avidin-biotin-peroxidase complex and diaminobenzidine as the chromogen. They were then immunostained to reveal parvalbumin using benzidine dihydrochloride as the chromogen. In both the light and electron microscopes, the morphological features and the afferent synaptic input of the parvalbumin-immunoreactive neurones were similar to those observed in other species. Similarly, the morphology and postsynaptic targets of the corticostriatal terminals were similar to those described in other species. Light microscopic examination revealed that the anterogradely labelled corticostriatal terminals were often in close apposition to the parvalbumin-positive neurones. At the electron microscopic level the biocytin-positive corticostriatal terminals were found to make asymmetrical synaptic contacts mainly with spines. The parvalbumin-positive neurones were seen to have an invaginated nucleus, extensive cytoplasm and relatively few spines. Parvalbumin-immunoreactive dendrites received a dense synaptic input consisting mainly of asymmetric synapses and only a few symmetric synapses. Biocytin-labelled corticostriatal terminals were often seen in asymmetrical synaptic contact with parvalbumin-immunoreactive dendrites. These results show that GABAergic interneurones identified on the basis of parvalbumin immunoreactivity, in addition to the projection neurones of the striatum, are under the direct influence of the cerebral cortex.
 ...
PMID:Cortical input to parvalbumin-immunoreactive neurones in the putamen of the squirrel monkey. 150 1

In order to determine whether the cholinergic fibres that innervate the substantia nigra make synaptic contact with dopaminergic neurons of the substantia nigra pars compacta, a double immunocytochemical study was carried out in the rat and ferret. Sections of perfusion-fixed mesencephalon were incubated first to reveal choline acetyltransferase immunoreactivity to label the cholinergic terminals and then tyrosine hydroxylase immunoreactivity to label the dopaminergic neurons. Each antigen was localized using peroxidase reactions but with different chromogens. At the light microscopic level, in confirmation of previous observations, choline acetyltransferase-immunoreactive axons and axonal boutons were found throughout the substantia nigra. The highest density of these axons was found in the pars compacta where they were often seen in close apposition to tyrosine hydroxylase-immunoreactive cell bodies and dendrites. In the ferret where the choline acetyltransferase immunostaining was particularly strong, bundles of immunoreactive fibres were seen to run through the reticulata perpendicular to the pars compacta. These bundles were associated with tyrosine hydroxylase-immunoreactive dendrites that descended into the reticulata. The choline acetyltransferase-immunoreactive fibres made "climbing fibre"-type multiple contacts with the tyrosine hydroxylase positive dendrites. At the electron microscopic level the choline acetyltransferase-immunoreactive axons were seen to give rise to vesicle-filled boutons that formed asymmetrical synaptic specializations with nigral dendrites and perikarya. The synapses were often associated with sub-junctional dense bodies. On many occasions the postsynaptic structures contained the tyrosine hydroxylase immunoreaction product, thus identifying them as dopaminergic. It is concluded that at least one of the synaptic targets of cholinergic terminals in the substantia nigra are the dendrites and perikarya of dopaminergic neurons and that in the ferret at least, the dendrites of dopaminergic neurons that descend into the pars reticulata receive multiple synaptic inputs from individual cholinergic axons.
 ...
PMID:Cholinergic input to dopaminergic neurons in the substantia nigra: a double immunocytochemical study. 167 2

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.
 ...
PMID:The GABA and substance P input to dopaminergic neurones in the substantia nigra of the rat. 170 87


1 2 3 4 5 6 7 8 9 10 Next >>