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

There are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT-HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT-HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri-SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, a light projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.
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PMID:Retinohypothalamic tract in the female albino rat: a study using horseradish peroxidase conjugated to cholera toxin. 171 Oct 60

In order to determine whether neurones in the parvicellular reticular formation are in direct synaptic contact with motoneurones innervating facial muscles, a combined retrograde and anterograde transport study was carried out in the rat. Animals received injections of the retrograde tracer cholera toxin B conjugated to horseradish peroxidase into facial muscles and of the anterograde tracer biocytin into the parvicellular reticular formation. The facial motor nucleus was then examined for anterograde and retrograde labelling in the light and electron microscopes. Retrogradely labelled neurones were found in the facial motor nucleus with a distribution that was dependent on the muscles injected. Terminals anterogradely labelled with biocytin from the parvicellular reticular formation was observed in the motor nucleus amongst the retrogradely labelled neurones. At the electron microscope, the retrogradely labelled cells were found to receive input from unlabelled terminals and from terminals that were anterogradely labelled from the injections of biocytin in the parvicellular reticular formation. The labelled terminals were 1-2 microns in diameter at the active zone and packed with spherical vesicles. They formed both symmetrical and asymmetrical synapses with their labelled or unlabelled targets. It is concluded that neurones in the parvicellular reticular formation form direct synaptic contact with motoneurones of facial muscles. This may represent a pathway by which the basal ganglia can directly influence orofacial movement, as the substantia nigra is known to project to that part of the reticular formation.
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PMID:Monosynaptic innervation of facial motoneurones by neurones of the parvicellular reticular formation. 753 50

An ultrastructural study is made of the synaptic contacts occurring between structures labelled anterogradely and retrogradely in the superficial dorsal horn following injections of cholera toxin subunit B or horseradish peroxidase in the dorsal reticular nucleus of the medulla oblongata of the rat. Both tracers revealed labelled axonal boutons in lamina I with round synaptic vesicles and a few large granular vesicles making asymmetrical synaptic contacts upon labelled somata and dendrites. After injections of Phaseolus vulgaris leucoagglutinin in the dorsal reticular nucleus, labelled boutons identical to those revealed by the two other tracers were presynaptic to unlabelled somata and dendrites. In addition, dorsoreticular neurons were labelled retrogradely following injections of cholera toxin subunit B into the superficial dorsal horn of the cervical enlargement. These observations show the occurrence of a reciprocal connection between dorsal reticular and lamina I neurons. Considering the putative excitatory nature of the axodendritic contacts in lamina I, a positive feedback circuit is suggested, whereby the nociceptive signals transmitted to the dorsal medullary reticular formation by marginal neurons are intensified.
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PMID:Descending projections from the medullary dorsal reticular nucleus make synaptic contacts with spinal cord lamina I cells projecting to that nucleus: an electron microscopic tracer study in the rat. 769 79

In order to determine whether neurones in the parvicellular reticular formation are in direct synaptic contact with motor neurones innervating masticatory muscles, a combined retrograde and anterograde transport study was carried out in the rat at both light and electron microscopic levels. The animals received injections of the retrograde tracers wheat germ agglutinin conjugated to horseradish peroxidase or cholera toxin B conjugated to horseradish peroxidase into the masticatory muscles and of the anterograde tracer biocytin into the ipsilateral parvicellular reticular formation. The trigeminal motor nucleus was then examined for both anterograde and retrograde labelling in the light and electron microscopes. Retrogradely labelled motor neurones were identified in the trigeminal motor nucleus. They were large and their locations within the nucleus depended on the muscle injected. In addition, terminals anterogradely labelled with the biocytin that was injected in the parvicellular reticular formation were identified throughout the motor nucleus. At the electron microscopic level, the retrogradely labelled cells were found to receive input both from distinct types of unlabelled terminals and from terminals that were anterogradely labelled from the parvicellular reticular formation. The labelled terminals comprised one of the four classes of afferent terminals, being 1-2 microns in diameter and densely packed with spherical vesicles. They formed mostly asymmetrical but also symmetrical synapses with the labelled perikarya and dendrites. Anterogradely labelled terminals were also observed to form both symmetrical and asymmetrical synaptic contacts with unlabelled structures in the motor nucleus. It is concluded that neurones in the parvicellular reticular formation form direct synaptic contact with motor neurones of masticatory muscles. This pathway may represent the anatomical substrate by which the reticular formation exerts at least part of its influence on mastication. Since the parvicellular reticular formation receives input from the substantia nigra pars reticulata, it is possible that this pathway represents a system whereby the basal ganglia directly influence orofacial movement.
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PMID:Monosynaptic innervation of trigeminal motor neurones involved in mastication by neurones of the parvicellular reticular formation. 825 13

The rostral ventrolateral medulla oblongata plays an important role in the control of arterial blood pressure and it has strong descending projections into the intermediolateral nucleus of the thoracic spinal cord, where the majority of sympathetic preganglionic neurons are located. The purpose of this study was to see whether these projections form synaptic contacts with sympathetic preganglionic neurons in the rat. Projections from both the lateral part of the rostral ventrolateral medulla (rostroventrolateral reticular nucleus) and from the more medial region (lateral paragigantocellular nucleus) were investigated separately in view of their different functional roles in sympatho-regulation and their different chemical composition. Using anterograde tract-tracing of descending medullary pathways with Phaseolus vulgaris leucoagglutinin and retrograde labelling of sympatho-adrenal preganglionic neurons with cholera B chain conjugated to horseradish peroxidase, the existence of monosynaptic connections was sought by electron microscopy. Synaptic inputs from both the lateral and medial aspects of the rostral ventrolateral medulla oblongata were found on identified sympathetic preganglionic neurons. Synaptic specializations were of both the symmetrical and asymmetrical type. The targets of boutons forming asymmetrical synaptic contacts differed according to their origin: boutons originating from neurons in the rostroventrolateral reticular nucleus were mainly in contact with dendrites of sympathetic preganglionic neurons, while those originating from the lateral paragigantocellular nucleus mainly innervated the cell bodies. Our observations provide anatomical support for the view that there are two distinct classes of sympatho-regulatory cells in the rostral ventrolateral medulla, each of which can directly influence the activity of sympathetic preganglionic neurons; they also emphasize the importance of detailed investigation of the subregions of the ventrolateral medulla with respect to their sympatho-regulatory functions.
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PMID:Monosynaptic projections from the rostral ventrolateral medulla oblongata to identified sympathetic preganglionic neurons. 833 59

The pathway conveying the descending inhibitory noradrenergic input elicited from the caudal ventrolateral medulla (VLM) onto the spinal cord dorsal horn was studied in the rat. Retrograde labeling with cholera toxin subunit B (CTb) injected into the dorsal horn was combined with immunostaining for dopamine-beta-hydroxylase (DBH) in the VLM and other brainstem nuclei containing noradrenergic cells. CTb-labeled neurons occurred in the lateral part of the VLM (VLMlat), located ventrolaterally to the DBH-immunoreactive cells of the A1 noradrenergic cell group. Neuronal profiles stained for CTb and DBH (double labeled) occurred in the A5 (31%), A6 (57%), and A7 (12%) noradrenergic cell groups. To ascertain whether noradrenergic cells targeting the spinal cord in those groups received projections from the VLMlat, this area was injected with the anterograde tracer biotinylated dextran amine (BDA). Labeled terminal fibers with boutons en passant were apposed to numerous double-stained neurons in the A5 cell group. Similar appositions occurred in small amounts in the ventral subcoerulear component of the A6. Correlated light and electron microscopic analyses of the labeled appositions revealed that the BDA-labeled axonal boutons contained spherical vesicles and were presynaptic at asymmetrical contacts to somata and dendritic profiles of the double-stained A5 neurons. These data indicate the occurrence of an indirect dysynaptic pathway connecting the VLM to the spinal cord, with a relay in the A5 cells. This pathway may convey the antinociceptive effects mediated by alpha 2-adrenoreceptors, which have been previously observed in the spinal cord following VLM stimulation.
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PMID:The ventrolateral medulla of the rat is connected with the spinal cord dorsal horn by an indirect descending pathway relayed in the A5 noradrenergic cell group. 889 48

The nucleus retroambiguus (NRA) is a group of premotor neurons at the transition between brainstem and spinal cord. It projects to certain motoneuronal cell groups, among which is a distinct set of motoneurons in the lumbar enlargement innervating muscles including iliopsoas, adductor longus, and hamstrings. To find out whether these NRA-motoneuronal projections are monosynaptic, injections of wheat germ-agglutinin horseradish peroxidase (WGA-HRP) into the NRA were combined with injections of cholera toxin subunit b (CTb) into the hamstring muscles. Electron microscopical examination revealed that the NRA terminal profiles make monosynaptic contacts with dendrites of motoneurons innervating these muscles. The NRA terminal profiles formed asymmetrical synapses, and contained spherical and a few dense core vesicles. These findings provide evidence of monosynaptic NRA-hindlimb motoneuronal projections which are likely to be excitatory.
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PMID:Evidence for monosynaptic projections from the nucleus retroambiguus to hindlimb motoneurons in the cat. 913 84

We examined a corticotectobulbar pathway from the orofacial motor cortex (OfM) to the parvicellular reticular formation (RFp), where numerous premotor neurons for the orofacial motor nuclei were known to be distributed, light and electron microscopically by using a combination of anterograde and retrograde tracing techniques. After contralateral injections of biotinylated dextranamine (BDA) into the OfM and cholera toxin B subunit (CTb) into the RFp, the overlapping distribution of ipsilateral axon terminals labeled with BDA and contralateral neurons labeled with CTb was found in the lateralmost part of the superior colliculus (SC). Furthermore, contralateral injections of BDA into the OfM and wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the RFp resulted in that ipsilateral axons labeled with BDA made asymmetrical synaptic contacts with the dendrites of contralateral SC neurons labeled with WGA-HRP.
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PMID:Demonstration of the corticotectobulbar pathway from the orofacial motor cortex to the parvicellular reticular formation in the rat. 916 52

In mammals, the suprachiasmatic nuclei are involved in the generation of biological rhythms and are synchronized by light input coming from the retina. The targets of retinal afferents and the involvement of neurons containing gastrin-releasing and vasoactive intestinal peptides in photic reception were investigated in the suprachiasmatic nuclei of the Syrian hamster by using light- and electron-microscopic immunocytochemistry. Cholera toxin was used to trace retinal fibers and Fos immunoreactivity to visualize cellular response to light stimulation. Ultrastructural observations were made in the intermediate third of the nuclei, the area of highest overlap for the immunoreactivities investigated. Gastrin-releasing peptide and vasoactive intestinal peptide cell bodies were localized in the ventral part of the nuclei; their dense immunoreactive fiber network often displayed synaptic contacts. Both neuropeptides were colocalized in elongated cells observed near the optic chiasm. Following a light pulse in the middle of the subjective night, Fos protein was expressed in most gastrin-releasing peptide perikarya and in some vasoactive intestinal peptide cells. Retinal terminals mostly occurred in the midline zone between the suprachiasmatic nuclei. Symmetrical or asymmetrical retinal synapses were observed on gastrin-releasing peptide-immunoreactive dendrites and somata, but never on vasoactive intestinal peptide neurons. These results are discussed in relation to the photic entrainment of the circadian clock.
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PMID:Neurons containing gastrin-releasing peptide and vasoactive intestinal polypeptide are involved in the reception of the photic signal in the suprachiasmatic nucleus of the Syrian hamster: an immunocytochemical ultrastructural study. 942 11

The morphology of retinal ganglion cells projecting to the superior colliculus (SC) of the thirteen-lined ground squirrel (Spermophilus tridecemlineatus) was studied after retrogradely labeling the cells with cholera toxin subunit B. On the basis of previous reports, labeled cells were classified as small (6-10 microm in soma diameter), medium (11-14 microm), or large (>14 microm). A total of 3,427 cells were studied. Small cells constituted 78% of the population, 21% were medium cells, and only 1% were classified as large. The morphology of medium-sized cells was studied in more detail because large cells were few in number and the staining of the dendritic tree of small cells was not optimal. The best labeled medium-sized cells were classified on the basis of the shape and size of their dendritic tree and the pattern of dendritic ramification. Four types were identified among the medium-sized ganglion cells. Two types were classified as symmetric delta-like and asymmetric delta-like cells considering the relative symmetric or asymmetric distribution of their dendritic branches and their similarities with the delta type of the cat. Approximately 52% of all the medium-sized cells studied were symmetrical delta-like, and 19% were classified as asymmetrical delta-like. These cells were also very similar to the symmetrical and asymmetrical directionally selective ganglion cells described in rabbit retina. Other cells were termed beta-like. They had the smallest dendritic tree diameter, and their tree size seemed to be related to retinal eccentricity. Medium beta-like cells comprised approximately 21% of all cells projecting to the SC. The fourth type was termed "acute angle" because most of their dendritic branches were relatively straight and formed acute angles (10-45 degrees) at their branching points. These cells were few in number (approximately 8% of all medium-sized cells studied) and did not resemble any reported previously in cats. Thus, a variety of morphological types of retinal ganglion cells projected to the SC. Of these, the symmetrical and asymmetrical delta-like cells appeared to correspond to the directionally selective type described in the ground squirrel (Michael, C.R. [1968] J. Neurophysiol. 31:257-267) and reported in the rabbit retina.
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PMID:Four retinal ganglion cell types that project to the superior colliculus in the thirteen-lined ground squirrel (Spermophilus tridecemlineatus). 962 90


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