The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Michael J. Mckinley - One of the best experts on this subject based on the ideXlab platform.
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Neurons in the median Preoptic Nucleus of the rat with collateral branches to the subfornical organ and supraoptic Nucleus
Brain research, 1992Co-Authors: Brian J. Oldfield, D.k. Hards, Michael J. MckinleyAbstract:A novel pathway between the subfornical organ and the supraoptic Nucleus involving the collateral branches of cell bodies situated in the lamina terminalis has been studied. Fluorogold was injected into the supraoptic Nucleus and rhodamine-labelled microspheres into the subfornical organ of rats. Nineteen % of neurons in the median Preoptic Nucleus and 30% of neurons in the OVLT projecting to the subfornical organ also had axons extending to the supraoptic Nucleus. These pathways may represent a novel trajectory for the rely of information from the lamina terminalis to the supraoptic Nucleus.
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Projections from the subfornical organ to the supraoptic Nucleus in the rat: ultrastructural identification of an interposed synapse in the median Preoptic Nucleus using a combination of neuronal tracers.
Brain research, 1991Co-Authors: Brian J. Oldfield, D.k. Hards, Michael J. MckinleyAbstract:The subfornical organ, along with other regions of the lamina terminalis, may contain osmoreceptors and is likely to be a site of action of blood-borne angiotensin II. The neural pathways by which these stimuli lead to vasopressin secretion, have been suggested to extend from the subfornical organ to hypothalamic sites of vasopressin production either directly or via synapses in an intervening Nucleus such as the median Preoptic Nucleus. In the present study, cholera toxin conjugated to horseradish peroxidase (CT/HRP) or colloidal gold (CT/Au) has been injected, respectively, into the subfornical organ and supraoptic Nucleus of the same animal. The anterograde and retrograde transport of the toxin from these two sites has made possible the identification, at the ultrastructural level, of a synapse in the median Preoptic Nucleus interposed in the pathway between the subfornical organ and the supraoptic Nucleus. Moreover, the presence of retrogradely transported CT/HRP and CT/Au in the same neurone in the median Preoptic Nucleus indicates that some neurones in this Nucleus have axons with collateral branches to both the subfornical organ and supraoptic Nucleus. Either or both of these pathways may transmit information related to the tonicity of the blood or circulating levels of angiotensin II to sites in the hypothalamus.
Jennifer M. Swann - One of the best experts on this subject based on the ideXlab platform.
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Stereological sex difference during development of the magnocelluar subdivision of the medial Preoptic Nucleus (MPN mag).
Brain research, 2007Co-Authors: E.k. Govek, Jennifer M. SwannAbstract:Abstract In Syrian hamsters, reproductive behaviors are initiated in the presence of appropriate hormonal and chemosensory cues. These cues are detected and integrated within a highly conserved pathway that converges on a small nuclear group in the lateral aspect of the medial Preoptic area, the magnocellular subdivision of the medial Preoptic Nucleus (MPN mag). The MPN mag plays a critical role in the regulation of male mating behavior—bilateral ablation of the MPN mag eliminates copulation. The MPN mag is sexually differentiated in both neuron number and density, but not in overall volume or volume of individual neurons. The current study used unbiased stereological methods to determine when the MPN mag becomes sexually differentiated. Our data indicate that the MPN mag becomes sexually dimorphic in volume and cell number after the critical period when steroid treatment induces male sexual behavior.
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The magnocellular medial Preoptic Nucleus I. sources of afferent input
Neuroscience, 2006Co-Authors: Joseph Wang, Jennifer M. SwannAbstract:The magnocellular medial Preoptic Nucleus plays a crucial role in the regulation of male sexual behavior in Syrian hamsters. Histological and behavioral studies suggest that the magnocellular medial Preoptic Nucleus regulates male mating behavior by integrating chemosensory and hormonal signals. The present study is the first to systematically identify the afferent connections of the magnocellular medial Preoptic Nucleus by tracing the uptake of cholera toxin B from deposits in the magnocellular medial Preoptic Nucleus of adult male Syrian hamsters. Our findings indicate that the magnocellular medial Preoptic Nucleus receives 1) chemosensory input from areas in the main and accessory olfactory pathways including the posterior medial bed Nucleus of the stria terminalis, anterior medial, anterior cortical and posterior cortical nuclei of the amygdala; 2) input from steroid responsive structures such as the posterior medial Nucleus of the amygdala, bed Nucleus of the stria terminalis, lateral septum, anteroventral periventricular Nucleus, medial Preoptic Nucleus, ventromedial Nucleus of the hypothalamus and arcuate Nucleus; 3) input from structures in the brainstem such as the subparafascicular thalamic Nucleus, peripeduncular Nucleus and the premamillary Nucleus in the hypothalamus that carry sensory information from the genitalia. The major afferent input to the magnocellular medial Preoptic Nucleus was confirmed by injecting anterograde tracer biotinylated dextran amine into the anterior medical Nucleus of the amygdala, the posterodorsal part of the medial Nucleus of the amygdala, the posteromedial part of the bed Nucleus of the stria terminalis and the posterointermediate part of the bed Nucleus of the stria terminalis. Our results support the hypothesis that the magnocellular medial Preoptic Nucleus is part of the chemosensory pathway that receives chemosensory and hormonal input to regulate mating behavior and suggest that the magnocellular medial Preoptic Nucleus may utilize information from the genitalia to regulate male mating behavior.
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Sex differences in the magnocellular subdivision of the medial Preoptic Nucleus in Syrian hamsters
Neuroscience, 2003Co-Authors: E.k. Govek, Joseph Wang, Jennifer M. SwannAbstract:Abstract Exposure to pheromonal cues initiates male mating behavior. Pheromones are processed within a pathway that converges on the magnocellular subdivision of the medial Preoptic Nucleus. Lesions of this area eliminate male copulatory behavior, but do not affect anogenital investigation. Exposure to pheromones stimulates cells of the magnocellular subdivision of the medial Preoptic Nucleus in a sex-specific manner. In this study, we hypothesize that sex differences in cell number may underlie sex differences in pheromone-induced neural stimulation. The current study used unbiased stereological methods to identify sexual dimorphisms in the magnocellular subdivision of the medial Preoptic Nucleus. Sex differences were found in the number and density of neurons, but not in overall volume or neuron volume. Consequently, the total volume is not sexually differentiated because neurons are more densely packed within the male magnocellular subdivision of the medial Preoptic Nucleus. These results support the hypothesis that additional neurons in the magnocellular subdivision of the medial Preoptic Nucleus are critical for the expression of male copulatory behaviors in adulthood. Furthermore, they suggest that sexual differentiation of the magnocellular subdivision of the medial Preoptic Nucleus is an important process that forms the anatomical basis for sex-specific behavioral responses to pheromonal stimulation.
Thierry Gallopin - One of the best experts on this subject based on the ideXlab platform.
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Multiparametric characterization of neuronal subpopulations in the ventrolateral Preoptic Nucleus.
Brain structure & function, 2016Co-Authors: Romain Dubourget, Thierry Gallopin, Aude Sangare, Hélène Geoffroy, Armelle RancillacAbstract:The characterization of neuronal properties is a necessary first step toward understanding how the ventrolateral Preoptic Nucleus (VLPO) neuronal network regulates slow-wave sleep (SWS). Indeed, the electrophysiological heterogeneity of VLPO neurons suggests the existence of subtypes that could differently contribute in SWS induction and maintenance. The aim of the present study was to define cell classes in the VLPO using an unsupervised clustering classification method. Electrophysiological features extracted from 289 neurons recorded in whole-cell patch-clamp allowed the identification of three main classes of VLPO neurons subdivided into five distinct subpopulations (cluster 1, 2a, 2b, 3a and 3b). The high occurrence of a low-threshold calcium spike (LTS) was one of the most distinctive features of cluster 1 and 3. Since sleep-promoting neurons are generally identified by their ability to generate an LTS and by their inhibitory response to noradrenaline (NA), 189 neurons from our dataset were also tested for this neurotransmitter. Neurons from cluster 3 were the most frequently inhibited by NA. Biocytin labeling and Neurolucida reconstructions of 112 neurons furthermore revealed a small dendritic arbor of cluster 3b neurons compared, in particular, to cluster 2b neurons. Altogether, we performed an exhaustive characterization of VLPO neuronal subtypes that is a crucial step toward a better understanding of the neuronal network within the VLPO and thereby sleep physiology.
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The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral Preoptic Nucleus.
Neuroscience, 2005Co-Authors: Thierry Gallopin, Pierre-hervé Luppi, Bruno Cauli, Yoshihiro Urade, Jean Rossier, Osamu Hayaishi, Bertrand Lambolez, Patrice FortAbstract:Recent research has shown that neurons in the ventrolateral Preoptic Nucleus are crucial for sleep by inhibiting wake-promoting systems, but the process that triggers their activation at sleep onset remains to be established. Since evidence indicates that sleep induced by adenosine, an endogenous sleep-promoting substance, requires activation of brain A2A receptors, we examined the hypothesis that adenosine could activate ventrolateral Preoptic Nucleus sleep neurons via A2A adenosine receptors in rat brain slices. Following on from our initial in vitro identification of these neurons as uniformly inhibited by noradrenaline and acetylcholine arousal transmitters, we established that the ventrolateral Preoptic Nucleus comprises two intermingled subtypes of sleep neurons, differing in their firing responses to serotonin, inducing either an inhibition (Type-1 cells) or an excitation (Type-2 cells). Since both cell types contained galanin and expressed glutamic acid decarboxylase-65/67 mRNAs, they potentially correspond to the sleep promoting neurons inhibiting arousal systems. Our pharmacological investigations using A1 and A2A adenosine receptors agonists and antagonists further revealed that only Type-2 neurons were excited by adenosine via a postsynaptic activation of A2A adenosine receptors. Hence, the present study is the first demonstration of a direct activation of the sleep neurons by adenosine. Our results further support the cellular and functional heterogeneity of the sleep neurons, which could enable their differential contribution to the regulation of sleep. Adenosine and serotonin progressively accumulate during arousal. We propose that Type-2 neurons, which respond to these homeostatic signals by increasing their firing are involved in sleep induction. In contrast, Type-1 neurons would likely play a role in the consolidation of sleep.
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Effect of the wake-promoting agent modafinil on sleep-promoting neurons from the ventrolateral Preoptic Nucleus: an in vitro pharmacologic study.
SLEEP, 2004Co-Authors: Thierry Gallopin, Pierre-hervé Luppi, Rambert Francis, Armand Frydman, Patrice FortAbstract:The pharmacologic profile of modafinil, an increasingly popular wake-promoting drug for narcolepsy treatment, differs from those of classic psychostimulants such as amphetamine. However, its brain targets are still a matter of debate. We hypothesized that modafinil could increase waking by inhibiting the sleep-promoting neurons from the ventrolateral Preoptic Nucleus (VLPO). Such action could be direct or indirect via the potentiation of inhibition mediated by waking neurotransmitters. We thus studied the effect of modafinil on the membrane potential and firing rate of VLPO neurons recorded in rat-brain slices. We further determined whether pretreatment with modafinil modifies the effect of noradrenaline, carbachol, serotonin, histamine, dopamine, or clonidine.
Patrice Fort - One of the best experts on this subject based on the ideXlab platform.
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The endogenous somnogen adenosine excites a subset of sleep-promoting neurons via A2A receptors in the ventrolateral Preoptic Nucleus.
Neuroscience, 2005Co-Authors: Thierry Gallopin, Pierre-hervé Luppi, Bruno Cauli, Yoshihiro Urade, Jean Rossier, Osamu Hayaishi, Bertrand Lambolez, Patrice FortAbstract:Recent research has shown that neurons in the ventrolateral Preoptic Nucleus are crucial for sleep by inhibiting wake-promoting systems, but the process that triggers their activation at sleep onset remains to be established. Since evidence indicates that sleep induced by adenosine, an endogenous sleep-promoting substance, requires activation of brain A2A receptors, we examined the hypothesis that adenosine could activate ventrolateral Preoptic Nucleus sleep neurons via A2A adenosine receptors in rat brain slices. Following on from our initial in vitro identification of these neurons as uniformly inhibited by noradrenaline and acetylcholine arousal transmitters, we established that the ventrolateral Preoptic Nucleus comprises two intermingled subtypes of sleep neurons, differing in their firing responses to serotonin, inducing either an inhibition (Type-1 cells) or an excitation (Type-2 cells). Since both cell types contained galanin and expressed glutamic acid decarboxylase-65/67 mRNAs, they potentially correspond to the sleep promoting neurons inhibiting arousal systems. Our pharmacological investigations using A1 and A2A adenosine receptors agonists and antagonists further revealed that only Type-2 neurons were excited by adenosine via a postsynaptic activation of A2A adenosine receptors. Hence, the present study is the first demonstration of a direct activation of the sleep neurons by adenosine. Our results further support the cellular and functional heterogeneity of the sleep neurons, which could enable their differential contribution to the regulation of sleep. Adenosine and serotonin progressively accumulate during arousal. We propose that Type-2 neurons, which respond to these homeostatic signals by increasing their firing are involved in sleep induction. In contrast, Type-1 neurons would likely play a role in the consolidation of sleep.
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Effect of the wake-promoting agent modafinil on sleep-promoting neurons from the ventrolateral Preoptic Nucleus: an in vitro pharmacologic study.
SLEEP, 2004Co-Authors: Thierry Gallopin, Pierre-hervé Luppi, Rambert Francis, Armand Frydman, Patrice FortAbstract:The pharmacologic profile of modafinil, an increasingly popular wake-promoting drug for narcolepsy treatment, differs from those of classic psychostimulants such as amphetamine. However, its brain targets are still a matter of debate. We hypothesized that modafinil could increase waking by inhibiting the sleep-promoting neurons from the ventrolateral Preoptic Nucleus (VLPO). Such action could be direct or indirect via the potentiation of inhibition mediated by waking neurotransmitters. We thus studied the effect of modafinil on the membrane potential and firing rate of VLPO neurons recorded in rat-brain slices. We further determined whether pretreatment with modafinil modifies the effect of noradrenaline, carbachol, serotonin, histamine, dopamine, or clonidine.
Brian J. Oldfield - One of the best experts on this subject based on the ideXlab platform.
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Neurons in the median Preoptic Nucleus of the rat with collateral branches to the subfornical organ and supraoptic Nucleus
Brain research, 1992Co-Authors: Brian J. Oldfield, D.k. Hards, Michael J. MckinleyAbstract:A novel pathway between the subfornical organ and the supraoptic Nucleus involving the collateral branches of cell bodies situated in the lamina terminalis has been studied. Fluorogold was injected into the supraoptic Nucleus and rhodamine-labelled microspheres into the subfornical organ of rats. Nineteen % of neurons in the median Preoptic Nucleus and 30% of neurons in the OVLT projecting to the subfornical organ also had axons extending to the supraoptic Nucleus. These pathways may represent a novel trajectory for the rely of information from the lamina terminalis to the supraoptic Nucleus.
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Projections from the subfornical organ to the supraoptic Nucleus in the rat: ultrastructural identification of an interposed synapse in the median Preoptic Nucleus using a combination of neuronal tracers.
Brain research, 1991Co-Authors: Brian J. Oldfield, D.k. Hards, Michael J. MckinleyAbstract:The subfornical organ, along with other regions of the lamina terminalis, may contain osmoreceptors and is likely to be a site of action of blood-borne angiotensin II. The neural pathways by which these stimuli lead to vasopressin secretion, have been suggested to extend from the subfornical organ to hypothalamic sites of vasopressin production either directly or via synapses in an intervening Nucleus such as the median Preoptic Nucleus. In the present study, cholera toxin conjugated to horseradish peroxidase (CT/HRP) or colloidal gold (CT/Au) has been injected, respectively, into the subfornical organ and supraoptic Nucleus of the same animal. The anterograde and retrograde transport of the toxin from these two sites has made possible the identification, at the ultrastructural level, of a synapse in the median Preoptic Nucleus interposed in the pathway between the subfornical organ and the supraoptic Nucleus. Moreover, the presence of retrogradely transported CT/HRP and CT/Au in the same neurone in the median Preoptic Nucleus indicates that some neurones in this Nucleus have axons with collateral branches to both the subfornical organ and supraoptic Nucleus. Either or both of these pathways may transmit information related to the tonicity of the blood or circulating levels of angiotensin II to sites in the hypothalamus.
