The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
J-F Cloutier - One of the best experts on this subject based on the ideXlab platform.
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Slits and Robo-2 regulate the coalescence of subsets of olfactory sensory neuron axons within the Ventral Region of the olfactory bulb
Developmental biology, 2012Co-Authors: Jin H. Cho, Joseph Wai Keung Kam, J-F CloutierAbstract:Abstract Olfactory sensory neurons (OSNs) project their axons to second-order neurons in the olfactory bulb (OB) to form a precise glomerular map and these stereotypic connections are crucial for accurate odorant information processing by animals. To form these connections, olfactory sensory neuron (OSN) axons respond to axon guidance molecules that direct their growth and coalescence. We have previously implicated the axon guidance receptor Robo-2 in the accurate coalescence of OSN axons within the dorsal Region of the OB ( Cho et al., 2011 ). Herein, we have examined whether Robo-2 and its ligands, the Slits, contribute to the formation of an accurate glomerular map within more Ventral Regions of the OB. We have ablated expression of Robo-2 in OSNs and assessed the targeting accuracy of axons expressing either the P2 or MOR28 olfactory receptors, which innervate two different Regions of the Ventral OB. We show that P2-positive axons, which express Robo-2, coalesce into glomeruli more Ventrally and form additional glomeruli in the OB of robo-2lox/lox;OMP-Cre mice. We also demonstrate that Robo-2-mediated targeting of P2 axons along the dorsoVentral axis of the OB is controlled by Slit-1 and Slit-3 expression. Interestingly, although MOR28-positive OSNs only express low levels of Robo-2, a reduced number of MOR28-positive glomeruli is observed in the OB of robo-2lox/lox;OMP-Cre mice. Taken together, our results demonstrate that Slits and Robo-2 are required for the formation of an accurate glomerular map in the Ventral Region of the OB.
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Requirement for Slit-1 and Robo-2 in zonal segregation of olfactory sensory neuron axons in the main olfactory bulb
Journal of Neuroscience, 2007Co-Authors: J-F CloutierAbstract:The formation of precise stereotypic connections in sensory systems is critical for the ability to detect and process signals from the environment. In the olfactory system, olfactory sensory neurons (OSNs) project axons to spatially defined glomeruli within the olfactory bulb (OB). A spatial relationship exists between the location of OSNs within the olfactory epithelium (OE) and their glomerular targets along the dorsoVentral axis in the OB. The molecular mechanisms underlying the zonal segregation of OSN axons along the dorsoVentral axis of the OB are poorly understood. Using robo-2/ (roundabout) and slit-1/ mice, we examined the role of the Slit family of axon guidance cues in the targeting of OSN axons during development. We show that a subset of OSN axons that normally project to the dorsal Region of the OB mistarget and form glomeruli in the Ventral Region in robo-2/ and slit-1/ mice. In addition, we show that the Slit receptor, Robo-2, is expressed in OSNs in a high dorsomedial to low ventrolateral gradient across the OE and that Slit-1 and Slit-3 are expressed in the Ventral Region of the OB. These results indicate that the dorsal-to-Ventral segregation of OSN axons are not solely defined by the location of OSNs within the OE but also relies on axon guidance cues.
Jin H. Cho - One of the best experts on this subject based on the ideXlab platform.
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Slits and Robo-2 regulate the coalescence of subsets of olfactory sensory neuron axons within the Ventral Region of the olfactory bulb
Developmental biology, 2012Co-Authors: Jin H. Cho, Joseph Wai Keung Kam, J-F CloutierAbstract:Abstract Olfactory sensory neurons (OSNs) project their axons to second-order neurons in the olfactory bulb (OB) to form a precise glomerular map and these stereotypic connections are crucial for accurate odorant information processing by animals. To form these connections, olfactory sensory neuron (OSN) axons respond to axon guidance molecules that direct their growth and coalescence. We have previously implicated the axon guidance receptor Robo-2 in the accurate coalescence of OSN axons within the dorsal Region of the OB ( Cho et al., 2011 ). Herein, we have examined whether Robo-2 and its ligands, the Slits, contribute to the formation of an accurate glomerular map within more Ventral Regions of the OB. We have ablated expression of Robo-2 in OSNs and assessed the targeting accuracy of axons expressing either the P2 or MOR28 olfactory receptors, which innervate two different Regions of the Ventral OB. We show that P2-positive axons, which express Robo-2, coalesce into glomeruli more Ventrally and form additional glomeruli in the OB of robo-2lox/lox;OMP-Cre mice. We also demonstrate that Robo-2-mediated targeting of P2 axons along the dorsoVentral axis of the OB is controlled by Slit-1 and Slit-3 expression. Interestingly, although MOR28-positive OSNs only express low levels of Robo-2, a reduced number of MOR28-positive glomeruli is observed in the OB of robo-2lox/lox;OMP-Cre mice. Taken together, our results demonstrate that Slits and Robo-2 are required for the formation of an accurate glomerular map in the Ventral Region of the OB.
Katia Gysling - One of the best experts on this subject based on the ideXlab platform.
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Lateral septum stimulation disinhibits dopaminergic neurons in the antero-Ventral Region of the Ventral tegmental area: Role of GABA-A alpha 1 receptors.
Neuropharmacology, 2017Co-Authors: Ignacio Vega-quiroga, Hector E Yarur, Katia GyslingAbstract:Abstract The mechanisms commanding the activity of dopaminergic neurons of the Ventral tegmental area (VTA) and the location of these neurons are relevant for the coding and expression of motivated behavior associated to reward-related signals. Anatomical evidence shows that several brain Regions modulate VTA dopaminergic neurons activity via multiple mechanisms. However, there is still scarce knowledge of how the lateral septum (LS) modulates VTA activity. We performed in-vivo dual-probe microdialysis to measure VTA dopamine, glutamate and GABA extracellular levels after LS stimulation in the presence or absence of GABAergic antagonists. Anterograde tracing and immunohistochemical analysis was used to reveal the anatomical relationship between LS and VTA. LS stimulation significantly increased dopamine and GABA, but not glutamate, VTA extracellular levels. Intra VTA infusion of bicuculline, GABA-A receptor antagonist, inhibited the increase of dopamine but not of GABA VTA levels induced by LS stimulation. Intra VTA infusion of indiplon, selective positive allosteric modulator of GABA-A receptors containing alpha1 subunit, significantly increases VTA dopamine extracellular levels induced by LS. Combined c-Fos and tyrosine hydroxylase immunohistochemistry, revealed that LS stimulation increases the activity of dopaminergic neurons in the antero-Ventral Region of the VTA. Consistently, anterograde tracing with biotinylated dextran amine revealed the existence of fibers arising from the LS to the antero-Ventral Region of the VTA. Taken together, our results suggest that LS modulates dopaminergic activity in the antero-Ventral Region of VTA by inhibiting GABAergic interneurons bearing GABA-A receptors containing alpha1 subunit.
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Studies of cholecystokinin in the rat bed nucleus of stria terminalis
Biochemical Pharmacology, 1993Co-Authors: María Estela Andrés, María Inés Forray, Carmen Gloria Barría, Katia GyslingAbstract:The release of cholecystokinin from the dorsal and Ventral Region of the rat bed nucleus of stria terminalis was studied. Minislices from both Regions were superfused with Krebs-Ringer-phosphate, and the cholecystokinin released into the physiological medium was concentrated previous to radioimmunoassay determination. For this purpose, cholecystokinin was adsorbed onto a C18 reverse-phase column and eluted with acetonitrile. Cholecystokinin standards (10-50 pg) were subjected to the above procedure, which allowed a 20- to 50-fold concentration of the peptide with an 80% recovery. Potassium-induced release of cholecystokinin from minislices of dorsal and Ventral Regions of the bed nucleus of stria terminalis was measured successfully using the above procedure to concentrate the peptide. Lesion of the stria terminalis, a fiber tract originating in the amygdala, provoked a significant decrease in cholecystokinin levels in the Ventral Region of the bed nucleus of strial terminalis. Thus, cholecystokinin released from minislices of the Ventral Region of the stria terminalis may be of amygdaloid origin.
Alfredo Rodríguez-tébar - One of the best experts on this subject based on the ideXlab platform.
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Vitronectin is expressed in the Ventral Region of the neural tube and promotes the differentiation of motor neurons
Development (Cambridge England), 1997Co-Authors: Juan Ramón Martínez-morales, Julio A. Barbas, Elisa Martí, Paola Bovolenta, David Edgar, Alfredo Rodríguez-tébarAbstract:The extracellular matrix protein vitronectin and its mRNA are present in the embryonic chick notochord, floor plate and in the Ventral neural tube at the time position of motor neuron generation. When added to cultures of neural tube explants of developmental stage 9, vitronectin promotes the generation of motor neurons in the absence of either notochord or exogenously added Sonic hedgehog. Conversely, the neutralisation of endogenous vitronectin with antibodies inhibits over 90% motor neuron differentiation in co-cultured neural tube/notochord explants, neural tube explants cultured in the presence of Sonic hedgehog, and in committed (stage 13) neural tube explants. Furthermore, treatment of embryos with anti-vitronectin antibodies results in a substantial and specific reduction in the number of motor neurons generated in vivo. These results demonstrate that vitronectin stimulates the differentiation of motor neurons in vitro and in vivo. Since the treatment of stage 9 neural tube explants with Sonic hedgehog resulted in induction of vitronectin mRNA expression before the expression of floor plate markers, we conclude that vitronectin may act either as a downstream effector in the signalling cascade induced by Sonic hedgehog, or as a synergistic factor that increases Shh-induced motor neuron differentiation.
Hironobu Ito - One of the best experts on this subject based on the ideXlab platform.
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Area dorsalis pars lateralis of the telencephalon in a teleost (Sebastiscus marmoratus) can be divided into dorsal and Ventral Regions.
Brain behavior and evolution, 1996Co-Authors: Yoichi Yamane, Masami Yoshimoto, Hironobu ItoAbstract:Area dorsalis pars lateralis was shown to be subdivided into a dorsal Region and a Ventral Region by a shallow groove on the telencephalic surface. In the dorsal Region, three layers were distinguished by Nissl staining; a surface layer I, a middle layer II, and a deep layer III. Although a three-layered structure was also observed in the Ventral Region, it was not as clear as that in the dorsal Region. Cells in area dorsalis pars lateralis were classified by Golgi-Cox staining into 5 types; small cells, horizontal cells, pyriform cells, inverted cells, and multipolar cells. The distribution of zinc was examined by the Neo-Timm method and found to be present in layers I and II and weakly in layer III of the dorsal Region but not in layers I and II of the Ventral Region. The presence of zinc in synaptic terminals in the dorsal Region was verified by analytical electron microscopy. Following separate and localized injections of horseradish peroxidase into dorsal and Ventral Regions, some different fiber connections were revealed. Both dorsal and Ventral Regions had reciprocal connections with ipsilateral area dorsalis pars centralis, area Ventralis pars supracommissuralis, area Ventralis pars dorsalis, area Ventralis pars posterior, nucleus prethalamicus, and had afferent connections from area Ventralis pars lateralis, area Ventralis pars intermedia, raphe nuclei, and locus ceruleus. Only the dorsal Region, however, received projections from contralateral area dorsalis pars centralis, ipsilateral area dorsalis pars dorsalis, area dorsalis pars medialis, and area dorsalis pars posterior and sent fibers to the inferior lobe, nucleus paracommissuralis, and optic tectum. Although area dorsalis pars lateralis had been thought to be a homogeneous Region of the primary visual area of the telencephalon, histochemistry of zinc and fiber connections of the Region indicates that the area is subdivided into two Regions: dorsal and Ventral.
