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)

We have successfully used biocytin as a retrograde tracer in the mammalian visual system. Retinal ganglion cells, pyramidal and stellate cortical neurons were labelled. Both pressure injections and gel implants were used successfully for retrograde labelling. Biocytin was detected using avidin conjugates and horseradish peroxidase histochemistry. Retrograde filling with biocytin proved to be more reliable and to allow better morphological resolution than other commonly used neurotracers such as horseradish peroxidase. The fine details of cell morphology observable by this method are comparable in many cases to the results obtained with intracellular tracer injections. The morphological resolution obtained with this method allows the study of brain microcircuits using extracellular deposits of biocytin.
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PMID:Biocytin as a retrograde tracer in the mammalian visual system. 130 45

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.
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PMID:Cortical input to parvalbumin-immunoreactive neurones in the putamen of the squirrel monkey. 150 1

Correlation of electrophysiological and morphological, including ultrastructural, characteristics of neurones is important for understanding the functional organization of neuronal systems. Further correlation with neurotransmitter content is essential for determining the neurochemical(s) used by a given neurone for propagating its signal. The two main neuronal markers presently available (lucifer yellow and horseradish peroxidase) are not satisfactory for correlating all three aspects. We have devised a new simple procedure whereby retinal interneurones can be labelled with biocytin by positive ionophoresis of an unbuffered solution. Biocytin readily crosses gap junctions thus revealing extensive networks of coupled cells. In the case of H1 horizontal cells, which are known to be GABAergic, the neurotransmitter can also be demonstrated by superimposed immunocytochemistry.
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PMID:Biocytin: intracellular staining, dye-coupling and immunocytochemistry in carp retina. 172 86

The projections and terminal ramifications of electrophysiologically characterized myenteric neurons of the guinea pig small intestine were studied after intracellular injection of the marker substance biocytin. Myenteric neurons were impaled with microelectrodes containing 4% biocytin in 2 M KCl (pH 7.4) and characterized electrophysiologically as either AH-neurons or S-neurons. AH-neurons were neurons in which action potentials were followed by prolonged after-hyperpolarizations (lasting greater than 4 seconds). S-neurons were neurons in which such hyperpolarizations were not seen. Electrical stimulation of internodal strands evoked prominent fast excitatory synaptic potentials in S-neurons, but not in AH-neurons. Biocytin was injected electrophoretically into the impaled AH-neurons by passage of hyperpolarizing current (0.6-0.8 nA for 5-15 minutes) through the recording electrode. The preparation was then fixed in Zamboni's fixative, dehydrated, and exposed to avidin coupled to horseradish peroxidase which allowed the injected biocytin to be visualised via a diaminobenzidine reaction. In many cases, the injected biocytin appeared to fill all the processes of injected AH-neurons that ramified within the myenteric plexus. The filled processes included axons running up to 4 mm within the plexus and profuse varicose terminals ramifying within both the ganglion containing the injected cell body and nearby ganglia. Most (90%) cell bodies of the injected AH-neurons had the morphology of Dogiel type II neurons; large, mostly smooth cell bodies with few short processes and several long processes. The other 10% of the AH-neurons had similar cell bodies and long processes but also had prominent short filamentous processes. This population was termed dendritic AH-neurons. The projections and terminals of 28 AH/Dogiel type II neurons and 7 dendritic AH-neurons were analysed in detail. Both types of neurons project circumferentially to provide terminals to nearby ganglia, but the AH/Dogiel type II neurons also provide terminals to their own ganglia while the dendritic AH-neurons typically do not. Although many of the injected AH-neurons had projections orally or anally along the intestine no evidence for a preferential direction of projection was obtained. Analysis of the areas and distributions of the terminal fields of the AH/Dogiel type II neurons suggests that each may contact several other myenteric neurons and that each myenteric neuron may receive input from about ten AH/Dogiel type II neurons.
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PMID:Ramifications of the axons of AH-neurons injected with the intracellular marker biocytin in the myenteric plexus of the guinea pig small intestine. 181 72

This study examined the distribution of axons in the lateral geniculate (LGN) and adjacent nuclei following injections of wheat germ agglutinin bound to horseradish peroxidase (WGA-HRP), [3H]proline and Biocytin into area 17 in ferrets. Terminal label was found in the LGN, perigeniculate (PGN), medial interlaminar (MIN) and lateral posterior (LP) nuclei. LGN label was more concentrated in the interlaminar zones. Analysis of axonal morphology showed that different axon types project to LGN, MIN and LP. These findings suggest that feedback pathways from area 17 are complex and composed of several classes of axons.
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PMID:The distribution and morphology of corticogeniculate axons in ferrets. 227 42

As an alternative for radioimmunoassays a new enzyme immunoassay (EIA) for the determination of 13,14-dihydro-15-keto PGF2 alpha (PGFM) has been developed. Biocytin was linked to PGFM by the N-hydroxysuccinimide method and the product (biocytinyl-PGFM) purified by reversed phase column chromatography. Biocytinyl-PGFM was used in the EIA as a bridge between the immobilized PGFM-antibody and streptavidin-peroxidase. The absolute sensitivity of the assay was about 160 amol (92% rel. binding) and required only 2 microliters plasma for PGFM estimation within the whole physiological range (0.08-20 pmol/ml). All variabilities were less than 14%. The described assay procedure may be of general applicability for other prostaglandins.
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PMID:A biotin-streptavidin amplified enzymeimmunoassay for 13,14-dihydro-15-keto-PGF2 alpha. 267 97

Biocytin is a biotin-lysine complex of low molecular weight containing about 65% biotin, which retains a high affinity for avidin. Since the latter molecule has been conjugated to several histochemical markers, the use of biocytin as an intracellular marker was investigated. Electrodes were filled with a solution of 4-6% biocytin dissolved in 0.5 M KCl and 0.05 M Tris buffer, pH 7-7.6. Neurons were recorded intracellularly in the supraoptic nucleus of an explant preparation of the rat supraoptico-neurohypophysial system and injected for 1-20 min with either hyperpolarizing or depolarizing current. Following variable recovery times, the explants were fixed in either 10% formalin or 4% paraformaldehyde overnight, sectioned on a vibratome, and incubated with the avidin-biotin complex (ABC) or avidin which had been conjugated to fluorescein, rhodamine, Texas Red or horseradish peroxidase and containing 1% Triton-X 100. A high percentage of injected neurons were recovered using each of the labels with about equal success. Both negative or positive current injection could be used with little electrode clogging. Labeling with fluorescent conjugates was qualitatively similar to that of Lucifer Yellow, whereas labeling with avidin coupled to horseradish peroxidase or with ABC was qualitatively similar to filling neurons directly with horseradish peroxidase. The advantages of this technique are the ease of injection of biocytin and the versatility in allowing the investigator to choose among light-emitting and light-absorbing images.
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PMID:A versatile means of intracellular labeling: injection of biocytin and its detection with avidin conjugates. 314 70

Morphological methods were used to examine injury-induced growth of peripheral and central axons of nociceptive mechanosensory neurones in the ventrocaudal (VC) clusters of the pleural ganglia of Aplysia californica. Pedal nerve crush transected all axons in the nerve while leaving the overlying sheath largely intact. Immunohistochemical staining was performed with an antibody to a sensory-neurone-specific peptide, sensorin-A. Following bilateral crush of pedal nerve p9, which innervates the tail, sensorin-A immunofluorescence was lost distal to the crush site within 2 days. Fine immunopositive fibres began to invade the crush region within 5 days. These fibres arborized in the crush region and gradually extended down the crushed nerve. Immunopositive fibres were found near the tail within 3 weeks. Similar results were obtained after injecting individual sensory neurone somata in the tail/p9 region of the VC cluster with biocytin. Biocytin injections and horseradish peroxidase injections 3 weeks after ipsilateral pedal nerve crush revealed new fibres projecting rostrally from the tail/p9 region of the VC cluster and entering the pleural-cerebral and pleural-abdominal connectives. Such projections were never observed in control, uncrushed preparations. These results demonstrate that nerve injury triggers extensive growth of both peripheral and central processes of the VC sensory neurones.
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PMID:Peripheral regeneration and central sprouting of sensory neurone axons in Aplysia californica following nerve injury. 750 2

The compatibility of neuronal tract-tracing and decalcification procedures was examined in salamander nasal chemosensory systems. Biocytin, but not horseradish peroxidase, retained its labeling capacity following rapid decalcification of the cranial bone. The combination of biocytin tract-tracing and decalcification procedures allows the visualization of labeled neurons and/or their projections within bony regions of intact specimens.
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PMID:Biocytin: a neuronal tracer compatible with rapid decalcification procedures. 751 99

Vestibulospinal neurons in the caudal half of the medial and descending vestibular nuclei terminate in the cervical spinal cord, not only in the ventral horn and intermediate zone but also in the dorsal horn. The purpose of the present study was to examine whether the areas containing these vestibulospinal neurons are reached by cervical primary afferents. In one group of experiments, wheat germ agglutinin-horseradish peroxidase conjugate and horseradish peroxidase were pressure injected into spinal ganglia C2-C8 and revealed anterogradely labeled fibers and boutons in the caudal part (caudal to the dorsal cochlear nucleus) of the ipsilateral medial and descending vestibular nuclei. This projection was verified in experiments in which wheat germ agglutinin-horseradish peroxidase conjugate was microiontophoretically injected into the caudal half of either the medial or the descending vestibular nuclei and revealed retrogradely labeled cells only in ipsilateral spinal ganglia C2-C7, with a maximum of cells in C3. In another group of experiments, after microiontophoretic injections of Phaseolus vulgaris leucoagglutinin or Biocytin into either the medial or the descending vestibular nuclei, anterogradely labeled fibers and boutons were present in the cervical spinal cord, mainly bilaterally in the dorsal horn (laminae I-VI) but also, to a lesser extent, in the ventral horn and intermediate zone. The existence of a loop that relays cervical primary afferent information to vestibulospinal neurons projecting to the cervical spinal cord, in particular the dorsal horn, may have implications for vestibular control over local information processing in the cervical dorsal horn.
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PMID:Cervical primary afferent input to vestibulospinal neurons projecting to the cervical dorsal horn: an anterograde and retrograde tracing study in the cat. 753 13


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