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)

PAP immunocytochemistry with an antiserum against serotonin (5-HT)-glutaraldehyde-protein conjugate (kindly donated by M. Geffard) was used to analyze the ultrastructural relationships of 5-HT axon terminals (varicosities) in the frontal (Fr1-Fr2), parietal (Par1), and occipital (Oc1M-Oc2) cortex of adult rats. One hundred-forty-five immunostained varicosities from Fr1-Fr2 (54 from layers I-II; 91 from layer VI) and 97 each from the upper layers (I-II) of Par1 and OcM1-Oc2 were examined in groups of serial thin sections (mean number of sections in series: 3.2 to 7.3). These terminals were of comparable shape and size in the 4 cortical sectors examined, and averaged 0.66 +/- 0.2 microns in mean diameter. The proportion of varicosities engaged in synaptic contact was evaluated by linear transformation of the relationship between the frequency of observed synaptic junctions and the number of thin sections available for examination. Reliability of the sampling was evidenced by a high coefficient of correlation (r greater than 0.95) in each cortical sector. The synaptic incidence extrapolated for whole varicosities ranged from 28% (layer VI of Fr1-Fr2) to 46% (Par1), without statistically significant differences between the 4 sectors examined. The interregional mean could thus be evaluated at 38%. The synaptic 5-HT terminals always made asymmetrical junctions, which were exclusively found on dendritic spines and shafts, and appeared more frequent on spines than shafts in the deep frontal and the upper occipital cortex. In all 4 sectors, dendritic shafts and spines and other axonal varicosities were frequently encountered in the immediate microenvironment of the immunostained varicosities. It is concluded that the cortical 5-HT innervation is predominantly nonjunctional throughout the neocortex of the adult rat, which reinforces earlier views of a highly divergent afferent system with particular functional properties and perhaps capable of widespread, global and/or sustained influences in this part of the brain.
 ...
PMID:Ultrastructural relationships of serotonin axon terminals in the cerebral cortex of the adult rat. 280 57

Sleep and wakefulness are two active states of the central nervous system, and sleep is further subdivided into two components: orthodox sleep (OS) and paradoxical sleep (PS). The relationships between sleep and wakefulness are asymmetrical inasmuch as wakefulness can override sleep whereas the converse occurs much more rarely. This probably indicates that sleep and wakefulness are mediated by different sorts of neurotransmitter systems. The types of neurotransmission, and the concepts of cotransmitter and neuromodulation are briefly outlined. The role of particular wiring of some neurones is also relevant in the understanding vigilance regulation. Activation of catecholamine pathways is coincident with wakefulness and deactivation is one of the conditions necessary for sleep to take place. The induction of PS is also positively related to brain catecholaminergic activity; the level of activation of these systems appears, however, to be lower during PS than during wakefulness. Serotonin, once thought to be the main transmitter in sleep, now appears to regulate the synthesis of yet unidentified sleep factors, responsible for OS and PS realization. Cholinergic mechanisms are also involved in wakefulness and in PS triggering. Such mechanisms may be part of the switch between wakefulness and PS, possibly by controlling the level of catecholaminergic activity. Gamma-aminobutyric acid also participates in the vigilance states, and benzodiazepines exert hypnogenic effects by modulating gamma-aminobutyric acid transmission. Sleep factors and hypnogenic peptides probably exist, but none of the substances so far described can yet be identified as the critical component in the subtle and still largely elusive mechanisms of vigilance regulation.
 ...
PMID:Neurochemical regulation of the states of alertness. 286 32

Recent evidence indicates that when 1-(3-trifluoromethylphenyl)piperazine (TFMPP) is used as a training drug in the drug discrimination paradigm it produces a stimulus effect that is site-selective at the 5-HT1B receptor. The present study sought to employ this procedure in order to assess the similarity of novel agents to TFMPP. First, rats were trained to reliably discriminate between the stimulus properties of intraperitoneally administered 1.0 mg/kg TFMPP and its vehicle. Following the acquisition of this discrimination, administration of various doses of TFMPP produced a typical dose-response relationship with an ED50 of 0.27 mg/kg. Rats were subsequently tested with another 5-HT1B specific agonist 1-(3-chlorophenyl)piperazine (mCPP) and a 5-HT releasing agent norfenfluramine and both produced TFMPP-like discriminative responding in a dose-dependent manner. In contrast, the 5-HT2 agonist 4-iodo-1-(2,5-dimethoxyphenyl)-2-aminopropane (DOI) did not generalize from TFMPP. Other drugs, previously trained in other rats and shown to generalize to TFMPP, viz., ethanol, tetrahydro-beta-carboline (THBC) and 3,4-methylenedioxymethamphetamine (MDMA) did not produce TFMPP-like responding. These results provide further evidence for the 5-HT1B receptor acting as the site for the discriminative effects of TFMPP. In addition, the transfer of discrimination between TFMPP and either ethanol, THBC or MDMA appears to be asymmetrical. Reasons for this one-way generalization are suggested.
 ...
PMID:Use of TFMPP stimulus properties as a model of 5-HT1B receptor activation. 325 60

Immunocytochemical methods were used to study the distribution and ultrastructure of serotonin (5-hydroxytryptamine; 5-HT) immunoreactive fibers innervating the monkey sensory-motor cortex. Beaded 5-HT positive fibers were found in all cortical layers of both areas but with relatively fewer in middle cortical layers. Examination of 2 micron-thick plastic sections at the light microscope level, revealed that the vast majority of the bouton-like structures on the fibers lay in the neuropil and not adjacent to neuronal somata. A few beaded immunoreactive fibers were seen around certain pyramidal and non-pyramidal cell somata, very occasionally forming modest pericellular ramifications. Serial reconstructions made from electron micrographs after resectioning the 2 micron-thick sections, revealed that the dilatations of the fibers are 5-HT positive boutons but the boutons examined rarely formed morphologically identifiable synaptic contacts. Of 191 reconstructed boutons only 5 made contacts with obvious membrane specializations, all of which were of the asymmetrical type. No immunoreactive synaptic contacts were seen on pyramidal cell somata in the cortex, nor on dendrites or somata in the white matter underlying the cortex, although 5-HT positive boutons commonly lay closely adjacent to neuronal profiles in both sites. 5-HT fibers in the cortex and white matter have a similar morphological appearance and both myelinated and unmyelinated types are seen.
 ...
PMID:A light and electron microscopic study of serotonin-immunoreactive fibers and terminals in the monkey sensory-motor cortex. 341 48

Serotonergic axonal endings in layers I and II of the dorsal horn of the medulla were identified by autoradiography. In adult cats, pretreated with a monoamine oxidase inhibitor, tritiated serotonin ([3H]5-HT) was topically applied onto the surface of the caudal medulla. Light autoradiographs from 1 micrometer sections demonstrated silver grains in both layers I and II. In EM autoradiographs, two categories of axonal endings were labeled by [3H]5-HT uptake: dome-shaped endings which form a single synapse and scalloped endings which form multiple synapses. Each category was further divided into several types based on morphological criteria. The [3H]5-HT-labeled endings synapse primarily on small caliber dendritic shafts and spines, with the dome-shaped endings forming both symmetrical and asymmetrical synapses and the scalloped endings forming only asymmetrical synapses. Dome-shaped endings were most common and two types were found in layers I and II while a third type was found only in layer II. Layer I contained a single type of scalloped ending while layer II contained three types of scalloped endings. In a series of experiments designed to provide another approach to identifying serotonergic endings, 5,6-dihydroxytryptamine, a serotonin neurotoxin, was either topically applied onto the caudal medulla or injected into the fourth ventricle. Following treatment with the neurotoxin, blackened degenerating dome-shaped and scalloped endings similar to those labeled in the [3H]5-HT uptake experiments were found in layers I and II. The presence of serotonergic endings in layer I suggests that some of these endings synapse on the dendrites of layer I projection neurons where they may inhibit the output of the projection neuron directly. Serotonergic endings in layer II may modulate the activity of layer II interneurons by synapsing directly on these interneurons. The interneurons in layer II may function by mediating the transfer of inputs from primary endings in these layers to layer I projection neurons.
 ...
PMID:Ultrastructural characterization of axonal endings in the substantia gelatinosa which take up [3H]serotonin. 615 52

Using a modification of the peroxidase-antiperoxidase technique, serotonin immunoreactivity was localized at the ultrastructural level in the nucleus of the solitary tract of the cat. Structures containing serotonin immunoreactivity included unmyelinated axons, varicosities (0.5 to 2 micrometers in diameter), and synaptic terminals. The serotonin-containing synaptic terminals were found less frequently than axons or varicosities. Within unmyelinated axons and varicosities, the immunoreactivity was associated mainly with large granular vesicles (80 to 150 nm). While large granular vesicles were found in all immunoreactive structures, greater numbers were observed in axons and nonsynaptic varicosities. Serial sections of several nonsynaptic serotonin-immunoreactive varicosities indicated the lack of synaptic specializations associated with these structures. In a typical section, only one or two granular vesicles were in synaptic terminals which contained numerous small clear vesicles. Serotonin-immunoreactive terminals formed asymmetrical contacts with dendrites and spines. No synaptic contacts involving immunoreactive terminals were found on cell bodies or other axonal structures. Serotonin-containing neuronal perikarya within the nucleus of the solitary tract were never observed. The abundance of nonsynaptic varicosities containing large granular vesicles suggests a possible neurohumoral role for serotonin within the feline nucleus of the solitary tract. This is discussed in relation to previous reports concerning the paucity of genuine synaptic contacts involving serotonin in other regions of the central nervous system. The presence of serotonin-immunoreactive terminals in the nucleus of the solitary tract also suggests its function as a putative neurotransmitter.
 ...
PMID:The ultrastructural localization of serotonin immunoreactivity within the nucleus of the solitary tract of the cat. 675 49

This paper is a short review of serotonergic (5-HT) fibers in the striatum. Data concerning biochemical demonstrations of striatal 5-HT and tryptophan hydroxylase and of ascending serotonergic pathways are quickly reviewed. This study deals particularly with the morphology of striatal 5-HT fibers. Little information concerning these fibers is available in the literature. Fluorescence histochemistry of 5-HT in the striatum is difficulty used, and ultrastructural studies are rare. In our work (ARLUISON and DE LA MANCHE, 1980), using cerebro-ventricular injections of tritiated serotonin in the rat and autoradiography three types of nerve terminals are labelled along the ventricle. The first has spherical and clear synaptic vesicles and is characterized by rather numerous asymmetrical synaptic contacts. The second has particularly small, often granular, synaptic vesicles of ovoid or tubular shape and shows rare synaptic contacts. The third category of labelled nerve terminals is provides with both of the previously described types of synaptic vesicles and shows few synaptic contacts. The heterogeneity of serotonergic nerve terminals in the striatum is compared to that observed in other regions of the brain, and the possibility of their origin in different midbrain raphe nuclei is discussed.
 ...
PMID:[The serotonergic fibers in the striatum. Ultrastructural characteristics (author's transl)]. 701 36

Morphine antagonized d-amphetamine circling in rats which had received unilateral 6-OHDA lesions of the striatum but failed to reduce the circling in rats with both a unilateral 6-OHDA striatal lesion and a raphe (5-HT) lesion. Naloxone precipitated withdrawal of morphine tolerant rats greatly enhanced d-amphetamine circling when the rats had a 6-OHDA lesion but not when both 6-OHDA and raphe lesions were present. It is concluded that 5-HT is necessary for the morphine-induced inhibition of the circling. The effect of morphine tolerance and naloxone precipitated withdrawal on brain 5-HT function was investigated using a putative 5-HT rotation model in which both a dopamine and a 5-HT agonist were administered to rats with an asymmetrical medial raphe lesion. The findings suggest that chronic treatment with morphine increases striatal 5-HT function.
 ...
PMID:Effect of morphine on circling behaviour in rats with 6-hydroxydopamine striatal lesions and electrolesions of the raphe nucleus. 719 77

Serotonin-immunoreactive somata in the pteropod mollusc Clione limacina were restricted to the cerebral and pedal ganglia. 10-14 pairs of cells were consistently found in the cerebral ganglia, including one large pair that had soma positions and axon branching patterns reminiscent of those of the metacerebral cells of other molluscs. Two clusters of somata were found on the midline near the cerebral commissure, one on the anterior-lateral margin and one posterior-laterally. A distinct paired cluster of up to nine somata was found on the dorso-lateral margin of the pedal ganglia, near the emergence of the pedal commissure. Up to five of these cells innervated the ipsilateral wing via the wing nerve. Dye-fills of these cells showed that they branch repeatedly in the ipsilateral wing and innervate the swim musculature. Double-labelling experiments indicated that the filled neurons were also serotonin-immunoreactive. Neurobiotin fills that were processed for electron microscopy revealed two types of terminals associated with the swim musculature: direct contacts and reactive terminals adjacent to non-labelled presynaptic terminals. Additional immunoreactive neurons in the pedal ganglia included the asymmetrical heart excitor neuron of the left pedal ganglion and up to nine ventral somata.
 ...
PMID:Serotonergic modulation of swimming speed in the pteropod mollusc Clione limacina. I. Serotonin immunoreactivity in the central nervous system and wings. 773 Jul 52

This work describes an experimental protocol studying action of Serotonin (5-HT) on vessels feeding human pharyngolaryngeal carcinoma. Right and left superior laryngeal arteries were obtained during total (pharyngo)laryngectomy. As tumor growth is asymmetrical, tumor and opposite side arteries were considered as tumor (T) and control (C) vessels, respectively. (T) and (C) vessels were cut in 3 mm rings and suspended in organ chambers for pharmacological studies. Preliminary results (2 tumors, 7 tumoral rings and 5 control rings) indicate that 5-HT induces specific vasoconstriction in (T) arteries feeding human pharyngolaryngeal carcinoma.
 ...
PMID:[Specific reactivity to serotonin of afferent vessels in human pharyngolaryngeal carcinoma. Methodology and initial results]. 775 5


<< Previous 1 2 3 4 Next >>