Search results for "Synaptic transmission."
showing 10 items of 178 documents
Minireview: pH and synaptic transmission
2013
AbstractAs a general rule a rise in pH increases neuronal activity, whereas it is dampened by a fall of pH. Neuronal activity per se also challenges pH homeostasis by the increase of metabolic acid equivalents. Moreover, the negative membrane potential of neurons promotes the intracellular accumulation of protons. Synaptic key players such as glutamate receptors or voltage-gated calcium channels show strong pH dependence and effects of pH gradients on synaptic processes are well known. However, the processes and mechanisms that allow controlling the pH in synaptic structures and how these mechanisms contribute to normal synaptic function are only beginning to be resolved.
Afferent and efferent projections of the dorsal anterior thalamic nuclei in the lizard Podarcis hispanica (Sauria, Lacertidae).
2002
The aim of this study was to investigate the afferent and efferent connections of the anterior thalamic nuclei in the lizard Podarcis hispanica. To identify potential sources of sensory inputs and to determine the fine organization of the projections of these thalamic nuclei to the telencephalon, we injected the sensitive tracer biotinylated dextran amine (BDA) into different nuclei of the anterior dorsal thalamus. We also injected BDA into several telencephalic areas in order to corroborate the results of thalamic injections. Our results show that the anterior thalamic nuclei receive projections from multiple areas and nuclei distributed throughout most of the brain, from rhombencephalon t…
Experimental study of electrical FitzHugh-Nagumo neurons with modified excitability
2006
International audience; We present an electronical circuit modelling a FitzHugh-Nagumo neuron with a modified excitability. To characterize this basic cell, the bifurcation curves between stability with excitation threshold, bistability and oscillations are investigated. An electrical circuit is then proposed to realize a unidirectional coupling between two cells, mimicking an inter-neuron synaptic coupling. In such a master-slave configuration, we show experimentally how the coupling strength controls the dynamics of the slave neuron, leading to frequency locking, chaotic behavior and synchronization. These phenomena are then studied by phase map analysis. The architecture of a possible ne…
Evidence for a modulatory role of cannabinoids on the excitatory NANC neurotransmission in mouse colon
2007
Abstract It is well accepted that endogenous cannabinoids and CB1 receptors are involved in the regulation of smooth muscle contractility and intestinal motility, through a mechanism mainly related to reduction of acetylcholine release from cholinergic nerve endings. Because, few data exist on a possible modulatory action of the cannabinoid agents on the non-adrenergic non-cholinergic (NANC) excitatory and inhibitory neurotransmission, the aim of the present study was to investigate the effects of cannabinoid drugs on the NANC responses elicited by electrical field stimulation (EFS) in the circular muscle of mouse proximal colon. Colonic contractions were monitored as changes in endoluminal…
Postsynaptic Secretion of BDNF and NT-3 from Hippocampal Neurons Depends on Calcium–Calmodulin Kinase II Signaling and Proceeds via Delayed Fusion Po…
2007
The mammalian neurotrophins (NTs) NGF, BDNF, NT-3, and NT-4 constitute a family of secreted neuronal growth factors. In addition, NTs are implicated in several forms of activity-dependent synaptic plasticity. Although synaptic secretion of NTs has been described, the intracellular signaling cascades that regulate synaptic secretion of NTs are far from being understood. Analysis of NT secretion at the subcellular level is thus required to resolve the role of presynaptic and postsynaptic NT secretion for synaptic plasticity. Here, we transfected cultures of dissociated rat hippocampal neurons with green fluorescent protein-tagged versions of BDNF and NT-3, respectively, and identified NT vesi…
Functional genomics indicate that schizophrenia may be an adult vascular-ischemic disorder
2015
AbstractIn search for the elusive schizophrenia pathway, candidate genes for the disorder from a discovery sample were localized within the energy-delivering and ischemia protection pathway. To test the adult vascular-ischemic (AVIH) and the competing neurodevelopmental hypothesis (NDH), functional genomic analyses of practically all available schizophrenia-associated genes from candidate gene, genome-wide association and postmortem expression studies were performed. Our results indicate a significant overrepresentation of genes involved in vascular function (P<0.001), vasoregulation (that is, perivascular (P<0.001) and shear stress (P<0.01), cerebral ischemia (P<0.001), neurode…
Circuit Specific Functions of Cannabinoid CB1 Receptor in the Balance of Investigatory Drive and Exploration
2011
Well balanced novelty seeking and exploration are fundamental behaviours for survival and are found to be dysfunctional in several psychiatric disorders. Recent studies suggest that the endocannabinoid (eCB) system is an important control system for investigatory drive. Pharmacological treatment of rodents with cannabinergic drugs results in altered social and object investigation. Interestingly, contradictory results have been obtained, depending on the treatment, drug concentration and experimental conditions. The cannabinoid type 1 (CB1) receptor, a central component of the eCB system, is predominantly found at the synapses of two opposing neuronal populations, i.e. on inhibitory GABAerg…
Accumbens-caudate-septal circuit as a system for hippocampal regulation: involvement of a GABAergic neurotransmission.
1992
Hippocampal-based epileptiform activity may reach the basal ganglia via the nucleus accumbens. Previous data suggested that caudate nucleus is able to influence hippocampal epilepsy, probably sending a projection to the septum. In order to test the hypothesis of a retrograde activation of accumbens-caudate pathway in hippocampal regulation, we electrically stimulated both caudate nucleus and nucleus accumbens and studied modifications of hippocampal EEG in the feline focal epilepsy model. We also performed bilateral electrolytic lesion of nucleus accumbens and repeated caudate stimulation. Results showed that nucleus accumbens stimulation was ineffective in modifying hippocampal epilepsy; o…
Multifaceted effects of oligodendroglial exosomes on neurons: impact on neuronal firing rate, signal transduction and gene regulation.
2014
Exosomes are small membranous vesicles of endocytic origin that are released by almost every cell type. They exert versatile functions in intercellular communication important for many physiological and pathological processes. Recently, exosomes attracted interest with regard to their role in cell–cell communication in the nervous system. We have shown that exosomes released from oligodendrocytes upon stimulation with the neurotransmitter glutamate are internalized by neurons and enhance the neuronal stress tolerance. Here, we demonstrate that oligodendroglial exosomes also promote neuronal survival during oxygen–glucose deprivation, a model of cerebral ischaemia. We show the transfer from…
Nicotinic receptor function in the mammalian central nervous system.
1995
The diversity of neuronal nicotinic receptors (nAChRs) in addition to their possible involvement in such pathological conditions as Alzheimer's disease have directed our research towards the characterization of these receptors in various mammalian brain areas. Our studies have relied on electrophysiological, biochemical, and immunofluorescent techniques applied to cultured and acutely dissociated hippocampal neurons, and have been aimed at identifying the various subtypes of nAChRs expressed in the mammalian central nervous system (CNS), at defining the mechanisms by which CNS nAChR activity is modulated, and at determining the ion permeability of CNS nAChR channels. Our findings can be sum…