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excitation/inhibition hippocampus

Elisabetta Coppi, Daniele Lana, Federica Cherchi, Irene Fusco, Daniela Buonvicino, Matteo Urru, Giuseppe Ranieri, Mirko Muzzi, Ludovica Iovino, Maria Grazia Giovannini, Anna Maria Pugliese, Alberto Chiarugi
Even though pharmacological approaches able to counteract age-dependent cognitive impairment have been highly investigated, drugs improving cognition and memory are still an unmet need. It has been hypothesized that sustaining energy dynamics within the aged hippocampus can boost memory storage by sustaining synaptic functioning and long term potentiation (LTP). Dexpramipexole (DEX) is the first-in-class compound able to sustain neuronal bioenergetics by interacting with mitochondrial F1Fo-ATP synthase. In the present study, for the first time we evaluated the effects of DEX on synaptic fatigue, LTP induction, learning and memory retention...
October 3, 2018: Neuropharmacology
Sophie Lepannetier, Roberta Gualdani, Sabrina Tempesta, Olivier Schakman, François Seghers, Anna Kreis, Xavier Yerna, Amina Slimi, Marie de Clippele, Nicolas Tajeddine, Thomas Voets, Robin S Bon, David J Beech, Fadel Tissir, Philippe Gailly
Group I metabotropic glutamate receptors, in particular mGluR5, have been implicated in various forms of synaptic plasticity that are believed to underlie declarative memory. We observed that mGluR5 specifically activated a channel containing TRPC1, an isoform of the canonical family of transient receptor potential (TRPC) channels highly expressed in CA1-3 regions of the hippocampus. TRPC1 is able to form tetrameric complexes with TRPC4 and/or TRPC5 isoforms. TRPC1/4/5 complexes have recently been involved in the efficiency of synaptic transmission in the hippocampus...
2018: Frontiers in Cellular Neuroscience
Zhiling Guo, Yiu Chung Tse, Ying Zhang, Qiang Sun, Haley A Vecchiarelli, Robert Aukema, Matthew N Hill, Tak Pan Wong, Patricia Boksa
There is strong evidence that immune activation from prenatal infection increases the risk for offspring to develop schizophrenia. The endocannabinoid (eCB) system has been implicated in the pathophysiology of schizophrenia while models of cortical dysfunction postulate an imbalance between neuronal excitation and inhibition in the disorder. The current study examined the impact of prenatal immune activation on eCB-mediated inhibitory mechanisms. We compared two forms of eCB-related plasticity of evoked inhibitory postsynaptic currents, namely depolarization-induced suppression of inhibition (DSI) and metabotropic glutamate receptor-induced long term depression (mGluR-iLTD), in both the dorsal and ventral hippocampus between adolescent offspring from rat dams that received either saline or bacterial lipopolysaccharide (LPS) during pregnancy...
September 23, 2018: European Neuropsychopharmacology: the Journal of the European College of Neuropsychopharmacology
Xiangchang Zeng, Kai Hu, Lulu Chen, Luping Zhou, Wei Luo, Chaopeng Li, Wenjing Zong, Siyu Chen, Qing Gao, Guirong Zeng, Dejian Jiang, Xiaohui Li, Honghao Zhou, Dong-Sheng Ouyang
The imbalance between the GABA-mediated inhibition and the glutamate-mediated excitation is the primary pathological mechanism of epilepsy. GABAergic and glutamatergic neurotransmission have become the most important targets for controlling epilepsy. Ginsenoside compound K (GCK) is a main metabolic production of the ginsenoside Rb1, Rb2, and Rc in the intestinal microbiota. Previous studies show that GCK promoted the release of GABA from the hippocampal neurons and enhanced the activity of GABAA receptors. GCK is shown to reduce the expression of NMDAR and to attenuate the function of the NMDA receptors in the brain...
2018: Frontiers in Pharmacology
Meral E Kızıltan, Bengi Gül Alpaslan, Çiğdem Özkara, Mustafa Uzan, Ayşegül Gündüz
Prepulse modulation (PPM) is an electrophysiological method which enables to assess sensory processing in vivo. Reflex responses may be facilitated or inhibited (prepulse inhibition, PPI) after a weak stimulus. Theoretically, in animal studies, the generator of PPI involves pedunculopontine nucleus which is modulated by various structures, including amygdala. We aimed to investigate whether or not there was a role of limbic structures in the generation of PPM in humans. For this purpose, we studied PPM of the blink reflex (BR) in 10 patients with mesial temporal lobe epilepsy (MTLE group) and in nine patients who had previously undergone amygdala resection for medically resistant MTLE (surgery group)...
September 22, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Da Song, Qinghu Yang, Yiran Lang, Zhaosen Wen, Zhen Xie, Da Zheng, Tianyi Yan, Yujun Deng, Hiroshi Nakanishi, Zhenzhen Quan, Hong Qing
The CA3 subregion of the hippocampus is important for rapid encoding, storage and retrieval of associative memories. Lesions and pharmacological inhibitions of hippocampal CA3 suggest that it is essential for different memories. However, how CA3 functions in spatial and episodic memory in different time scales (i.e. short-term versus long term) without permanent lesions has not been systematically investigated yet. Taking advantage of the chemogenetic access to opsins, this study used luminopsins, fusion proteins of luciferase and optogenetic elements, to manipulate neuronal activity in CA3 during memory tasks over a range of spatial and temporal scales...
September 19, 2018: Neurobiology of Learning and Memory
Birgit A Hörmer, Dilip Verma, Elisabeth Gasser, Anna Wieselthaler-Hölzl, Herbert Herzog, Ramon O Tasan
Posttraumatic stress disorder is characterized by contextually inappropriate, dys-regulated and generalized fear expression and often resistant to therapy. The hippocampus integrates contextual information into spatial and emotional memories, but how diverse modulatory neurotransmitters are shaping this process is not known. Neuropeptide Y is a peptide-neurotransmitter, which modulates hippocampal excitability by activating several G-protein-coupled receptors. Postsynaptic Y1 receptors create strong anxiolytic and fear-suppressing behavior, while pre-synaptic Y2 receptors (Y2R) are mainly anxiogenic...
September 17, 2018: Neuropharmacology
Mehdi Sadegh, Mohammad Hassan Sakhaie
Systemic injection of LPS changes neuronal excitability and increase susceptibility for convulsions. Carvacrol exerts neuroprotective and antiepileptic effects in animal models. Herein, we investigated the anticonvulsive effect of carvacrol on LPS induced seizure severity and possible involvement of the hippocampal COX-1 and -2 activities in this effect. Adult male wistar rats were used. LPS was injected (400 μg/kg; i.p.) four hours before the PTZ (80 mg/kg; i.p.) injection. Carvacrol was injected (100 mg/kg; i...
September 18, 2018: Metabolic Brain Disease
Alexandra P Chatzikalymniou, Frances K Skinner
Oscillations in local field potentials (LFPs) are prevalent and contribute to brain function. An understanding of the cellular correlates and pathways affecting LFPs is needed, but many overlapping pathways in vivo make this difficult to achieve. A prevalent LFP rhythm in the hippocampus associated with memory processing and spatial navigation is the θ (3-12 Hz) oscillation. θ rhythms emerge intrinsically in an in vitro whole hippocampus preparation and this reduced preparation makes it possible to assess the contribution of different cell types to LFP generation...
July 2018: ENeuro
Tanvi Paretkar, Eugene Dimitrov
The encoding, consolidation and retrieval of memories is a multifaceted process that depends strongly on the optimal level of arousal but high levels of arousal may trigger anxiety, which negatively impacts the memory processing by the brain. We investigated the role of CRH neurons in the central amygdala (CeA) for their capacity to modulate both, the anxiety-like behavior and hippocampus-dependent memory. First, we activated the CRH neurons in CeA using cre-dependent AAV-DREADD in CRH-cre mice. The activation of CeA CRH neurons increased the anxiety-like behavior in Elevated-O maze (O-maze) and Light-Dark box (LDB)...
October 15, 2018: Neuroscience
Camille Dumon, Diabe Diabira, Ilona Chudotvorova, Francesca Bader, Semra Sahin, Jinwei Zhang, Christophe Porcher, Gary Wayman, Igor Medina, Jean-Luc Gaiarsa
Brain computations rely on a proper balance between excitation and inhibition which progressively emerges during postnatal development in rodent. γ-Aminobutyric acid (GABA) neurotransmission supports inhibition in the adult brain but excites immature rodent neurons. Alterations in the timing of the GABA switch contribute to neurological disorders, so unveiling the involved regulators may be a promising strategy for treatment. Here we show that the adipocyte hormone leptin sets the tempo for the emergence of GABAergic inhibition in the newborn rodent hippocampus...
August 14, 2018: ELife
Yu-Jing Ding, Yu Song, Jun-Xiu Liu, Ya-Li Du, Li Zhu, Fu-Rong Ma
Background: Tinnitus is a common disorder that causes significant morbidity; however, the neurophysiological mechanism is not yet fully understood. A relationship between tinnitus and limbic system has been reported. As a significant component of the limbic system, the hippocampus plays an important role in various pathological processes, such as emotional disturbance, decreased learning ability, and deterioration of memory. This study was aimed to explore the role of the hippocampus in the generation of tinnitus by electrophysiological technology...
August 20, 2018: Chinese Medical Journal
Andrew L Eagle, Elizabeth S Williams, Joseph A Beatty, Charles L Cox, Alfred J Robison
Both the function of hippocampal neurons and hippocampus-dependent behaviors are dependent on changes in gene expression, but the specific mechanisms that regulate gene expression in hippocampus are not yet fully understood. The stable, activity-dependent transcription factor ΔFosB plays a role in various forms of hippocampal-dependent learning and in the structural plasticity of synapses onto CA1 neurons. The authors examined the consequences of viral-mediated overexpression or inhibition of ΔFosB on the function of adult mouse hippocampal CA1 neurons using ex vivo slice whole-cell physiology...
July 2018: ENeuro
Amir Segev, Masaya Yanagi, Daniel Scott, Sarah A Southcott, Jacob M Lister, Chunfeng Tan, Wei Li, Shari G Birnbaum, Saïd Kourrich, Carol A Tamminga
Recent findings from in vivo-imaging and human post-mortem tissue studies in schizophrenic psychosis (SzP), have demonstrated functional and molecular changes in hippocampal subfields that can be associated with hippocampal hyperexcitability. In this study, we used a subfield-specific GluN1 knockout mouse with a disease-like molecular perturbation expressed only in hippocampal dentate gyrus (DG) and assessed its association with hippocampal physiology and psychosis-like behaviors. First, we used whole-cell patch-clamp recordings to measure the physiological changes in hippocampal subfields and cFos immunohistochemistry to examine cellular excitability...
July 23, 2018: Molecular Psychiatry
Simone F Carron, Edwin B Yan, Benjamin J Allitt, Ramesh Rajan
Changes in inhibition following traumatic brain injury (TBI) appear to be one of the major factors that contribute to excitation:inhibition imbalance. Neuron pathology, interneurons in particular evolves from minutes to weeks post injury and follows a complex time course. Previously, we showed that in the long-term in diffuse TBI (dTBI), there was select reduction of specific dendrite-targeting neurons in sensory cortex and hippocampus while in motor cortex there was up-regulation of specific dendrite-targeting neurons...
September 15, 2018: Neuroscience
Alexandra Olimpio Siqueira Cunha, Cesar Celis Ceballos, Júnia Lara de Deus, Rodrigo Felipe de Oliveira Pena, José Antonio Cortes de Oliveira, Antonio Carlos Roque, Norberto Garcia-Cairasco, Ricardo Maurício Leão
Despite the many studies focusing on epilepsy, a lot of the basic mechanisms underlying seizure susceptibility are mainly unclear. Here, we studied cellular electrical excitability, as well as excitatory and inhibitory synaptic neurotransmission of CA1 pyramidal neurons from the dorsal hippocampus of a genetic model of epilepsy, the Wistar Audiogenic Rat (WARs) in which limbic seizures appear after repeated audiogenic stimulation. We examined intrinsic properties of neurons, as well as EPSCs evoked by Schaffer-collateral stimulation in slices from WARs and Wistar parental strain...
July 10, 2018: Scientific Reports
Christoph Anacker, Victor M Luna, Gregory S Stevens, Amira Millette, Ryan Shores, Jessica C Jimenez, Briana Chen, René Hen
Adult neurogenesis in the dentate gyrus of the hippocampus is highly regulated by environmental influences, and functionally implicated in behavioural responses to stress and antidepressants1-4 . However, how adult-born neurons regulate dentate gyrus information processing to protect from stress-induced anxiety-like behaviour is unknown. Here we show in mice that neurogenesis confers resilience to chronic stress by inhibiting the activity of mature granule cells in the ventral dentate gyrus (vDG), a subregion that is implicated in mood regulation...
July 2018: Nature
Naoki Yamawaki, Kevin A Corcoran, Anita L Guedea, Gordon M G Shepherd, Jelena Radulovic
Learning to associate stressful events with specific environmental contexts depends on excitatory transmission in the hippocampus, but how this information is transmitted to the neocortex for lasting memory storage is unclear. We identified dorsal hippocampal (DH) projections to the retrosplenial cortex (RSC), which arise mainly from the subiculum and contain either the vesicular glutamate transporter 1 (vGlut1) or vGlut2. Both vGlut1+ and vGlut2+ axons strongly excite and disynaptically inhibit RSC pyramidal neurons in superficial layers, but vGlut2+ axons trigger greater inhibition that spreads to deep layers, indicating that these pathways engage RSC circuits via partially redundant, partially differentiated cellular mechanisms...
June 6, 2018: Cerebral Cortex
Siddhartha Mondragón-Rodríguez, Ning Gu, Frederic Manseau, Sylvain Williams
Alzheimer's disease (AD) is defined by the presence of amyloid-β (Aβ) and tau protein aggregates. However, increasing data is suggesting that brain network alterations rather than protein deposition could account for the early pathogenesis of the disease. In the present study, we performed in vitro extracellular field recordings in the CA1/subiculum area of the hippocampus from 30 days old J20-TG-AD mice. Here, we found that theta oscillations were significantly less rhythmic than those recorded from control group...
2018: Frontiers in Cellular Neuroscience
Catia M Teixeira, Zev B Rosen, Deepika Suri, Qian Sun, Marc Hersh, Derya Sargin, Iva Dincheva, Ashlea A Morgan, Stephen Spivack, Anne C Krok, Tessa Hirschfeld-Stoler, Evelyn K Lambe, Steven A Siegelbaum, Mark S Ansorge
The efficacy and duration of memory storage is regulated by neuromodulatory transmitter actions. While the modulatory transmitter serotonin (5-HT) plays an important role in implicit forms of memory in the invertebrate Aplysia, its function in explicit memory mediated by the mammalian hippocampus is less clear. Specifically, the consequences elicited by the spatio-temporal gradient of endogenous 5-HT release are not known. Here we applied optogenetic techniques in mice to gain insight into this fundamental biological process...
June 6, 2018: Neuron
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