Epileptiform activity in microcultures containing small numbers of hippocampal neurons

1990 ◽  
Vol 64 (5) ◽  
pp. 1390-1399 ◽  
Author(s):  
M. M. Segal ◽  
E. J. Furshpan
Keyword(s):  
Glial Cells ◽  
Hippocampal Neurons ◽  
Epileptiform Activity ◽  
Synaptic Activity ◽  
Synaptic Connections ◽  
Mass Cultures

1. Microcultures were grown containing small numbers of hippocampal neurons. The neurons grew on glial cells attached to patches of either collagen or palladium. A layer of agarose underlying the microcultures prevented connections from forming between nearby microcultures. 2. Neurons formed strong chemical synaptic connections within each microculture, with monosynaptic fast-excitatory, fast-inhibitory, and slow-inhibitory synaptic actions. 3. Small networks with as few as two neurons generated epileptiform activity that closely resembled the epileptiform activity seen in mass cultures containing thousands of neurons. The epileptiform activity was observed when microcultures that were grown for weeks in blockers of synaptic activity (kynurenate and elevated Mg2+) were washed free of these blockers. 4. Such a microculture technique allows study of epileptiform activity in a simplified system and facilitates analysis of the synaptic actions underlying the epileptiform activity.

scholarly journals Purinergic signaling and the functioning of the nervous system cells

2015 ◽  
Vol 20 (5) ◽  
Author(s):  
Kamila Puchałowicz ◽  
Irena Baranowska-Bosiacka ◽  
Violetta Dziedziejko ◽  
Dariusz Chlubek
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Purinergic Signaling ◽  
Physiological State ◽  
P2y Receptors ◽  
Mechanisms Of Action ◽  
Synaptic Activity ◽  
Extracellular Nucleotides ◽  
Synaptic Connections ◽  
P2x And P2y Receptors

AbstractPurinergic signaling in the nervous system has been the focus of a considerable number of studies since the 1970s. The P2X and P2Y receptors are involved in the initiation of purinergic signaling. They are very abundant in the central and peripheral nervous systems, where they are expressed on the surface of neurons and glial cells - microglia, astrocytes, oligodendrocytes and Schwann cells and the precursors of the latter two. Their ligands - extracellular nucleotides - are released in the physiological state by astrocytes and neurons forming synaptic connections, and are essential for the proper functioning of nervous system cells. Purinergic signaling plays a crucial role in neuromodulation, neurotransmission, myelination in the CNS and PNS, intercellular communication, the regulation of ramified microglia activity, the induction of the response to damaging agents, the modulation of synaptic activity and other glial cells by astrocytes, and the induction of astrogliosis. Understanding these mechanisms and the fact that P2 receptors and their ligands are involved in the pathogenesis of diseases of the nervous system may help in the design of drugs with different and more effective mechanisms of action.

Fast NMDA Receptor–Mediated Synaptic Currents in Neurons From Mice Lacking the ε2 (NR2B) Subunit

2000 ◽  
Vol 83 (1) ◽  
pp. 616-620 ◽  
Author(s):  
Kenneth R. Tovar ◽  
Kathleen Sprouffske ◽  
Gary L. Westbrook
Keyword(s):  
Nmda Receptor ◽  
Hippocampal Neurons ◽  
Postsynaptic Membrane ◽  
Synaptic Activity ◽  
Wild Type ◽  
Nmda Receptor Subunit ◽  
Deactivation Kinetics ◽  
Low Concentrations ◽  
Specific Antagonist

The N-methyl-d-aspartate (NMDA) receptor has been implicated in the formation of synaptic connections. To investigate the role of the ε2 (NR2B) NMDA receptor subunit, which is prominently expressed during early development, we used neurons from mice lacking this subunit. Although ε2−/− mice die soon after birth, we examined whether NMDA receptor targeting to the postsynaptic membrane was dependent on the ε2 subunit by rescuing hippocampal neurons from these mice and studying them in autaptic cultures. In voltage-clamp recordings, excitatory postsynaptic currents (EPSCs) from ε2−/− neurons expressed an NMDA receptor–mediated EPSC that was apparent as soon as synaptic activity developed. However, compared with wild-type neurons, NMDA receptor–mediated EPSC deactivation kinetics were much faster and were less sensitive to glycine, but were blocked by Mg2+ or AP5. Whole cell currents from ε2−/− neurons were also more sensitive to block by low concentrations of Zn2+ and much less sensitive to the ε2-specific antagonist ifenprodil than wild-type currents. The rapid NMDA receptor–mediated EPSC deactivation kinetics and the pharmacological profile from ε2−/−neurons are consistent with the expression of ζ1/ε1 diheteromeric receptors in excitatory hippocampal neurons from mice lacking the ε2 subunit. Thus ε1 can substitute for the ε2 subunit at synapses and ε2 is not required for targeting of NMDA receptors to the postsynaptic membrane.

A Simple Depletion Model of the Readily Releasable Pool of Synaptic Vesicles Cannot Account for Paired-Pulse Depression

2007 ◽  
Vol 97 (1) ◽  
pp. 948-950 ◽  
Author(s):  
Jane M. Sullivan
Keyword(s):  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Synaptic Activity ◽  
Excitatory Synapses ◽  
Short Term ◽  
Paired Pulse ◽  
Short Term Plasticity ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Paired Pulse Depression

Paired-pulse depression (PPD) is a form of short-term plasticity that plays a central role in processing of synaptic activity and is manifest as a decrease in the size of the response to the second of two closely timed stimuli. Despite mounting evidence to the contrary, PPD is still commonly thought to reflect depletion of the pool of synaptic vesicles available for release in response to the second stimulus. Here it is shown that PPD cannot be accounted for by depletion at excitatory synapses made by hippocampal neurons because PPD is unaffected by changes in the fraction of the readily releasable pool (RRP) released by the first of a pair of pulses.

Reverse Optical Trawling for Synaptic Connections In Situ

2009 ◽  
Vol 102 (1) ◽  
pp. 636-643 ◽  
Author(s):  
Takuya Sasaki ◽  
Genki Minamisawa ◽  
Naoya Takahashi ◽  
Norio Matsuki ◽  
Yuji Ikegaya
Keyword(s):  
Network Connectivity ◽  
Synaptic Activity ◽  
Calcium Transients ◽  
Synaptic Connections ◽  
False Positive Error ◽  
Presynaptic Neuron ◽  
Promising Tool ◽  
On Line ◽  
False Positive Error Rate ◽  
Presynaptic Neurons

We introduce a new method to unveil the network connectivity among dozens of neurons in brain slice preparations. While synaptic inputs were whole cell recorded from given postsynaptic neurons, the spatiotemporal firing patterns of presynaptic neuron candidates were monitored en masse with functional multineuron calcium imaging, an optical technique that records action potential–evoked somatic calcium transients with single-cell resolution. By statistically screening the neurons that exhibited calcium transients immediately before the postsynaptic inputs, we identified the presynaptic cells that made synaptic connections onto the patch-clamped neurons. To enhance the detection power, we devised the following points: 1) [K+]e was lowered and [Ca2+]e and [Mg2+]e were elevated, to reduce background synaptic activity and minimize the failure rate of synaptic transmission; and 2) a small fraction of presynaptic neurons was specifically activated by glutamate applied iontophoretically through a glass pipette that was moved to survey the presynaptic network of interest (“trawling”). Then we could theoretically detect 96% of presynaptic neurons activated in the imaged regions with a 1% false-positive error rate. This on-line probing technique would be a promising tool in the study of the wiring topography of neuronal circuits.

Altered desensitization produces enhancement of EPSPs in neocortical neurons

1994 ◽  
Vol 72 (2) ◽  
pp. 1032-1036 ◽  
Author(s):  
M. R. Pelletier ◽  
J. J. Hablitz
Keyword(s):  
Nmda Receptors ◽  
Time Course ◽  
Glutamate Release ◽  
Epileptiform Activity ◽  
Brain Slices ◽  
Synaptic Activity ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Resting Membrane Potential ◽  
Bath Application

1. Neocortical brain slices were prepared from rats (35–50 days of age) and maintained in vitro. Intracellular recordings were obtained from neurons in cortical layers II/III. The effect of bath application of cyclothiazide (CYZ), a potent blocker of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor desensitization, on evoked synaptic activity and passive membrane properties was investigated. 2. Bath application of CYZ did not significantly affect resting membrane potential, input resistance, or repetitive firing. CYZ increased both the amplitude and duration of evoked excitatory postsynaptic potentials (EPSPs). Polysynaptic responses were also augumented. These effects persisted after the blockade of N-methyl-D-aspartate (NMDA) receptors with D-2-amino-5-phosphonovaleric acid (D-APV). The magnitude of these effects appeared to vary directly with stimulation intensity and presumably, amount of glutamate release. 3. Epileptiform activity was induced by bath application of bicuculline methiodide. The amplitude and duration of evoked paroxysmal discharges were increased by CYZ. Similar results were seen in presence of D-APV. 4. These results indicate that CYZ has significant effects on synaptic transmission. Desensitization of non-NMDA receptors may be an important mechanism for determining the time course of EPSPs and in curtailing epileptiform responses in the rat neocortex.

scholarly journals Neuron-based high-content assay and screen for CNS active mitotherapeutics

2020 ◽  
Vol 6 (2) ◽  
pp. eaaw8702 ◽  
Author(s):  
Boglarka H. Varkuti ◽  
Miklos Kepiro ◽  
Ze Liu ◽  
Kyle Vick ◽  
Yosef Avchalumov ◽  
...  
Keyword(s):  
Small Molecule ◽  
Hippocampal Neurons ◽  
Mitochondrial Dynamics ◽  
Synaptic Activity ◽  
Glutamate Toxicity ◽  
Primary Neurons ◽  
Screening Assay ◽  
Dynamics And Function ◽  
Small Molecule Modulators ◽  
And Function

Impaired mitochondrial dynamics and function are hallmarks of many neurological and psychiatric disorders, but direct screens for mitotherapeutics using neurons have not been reported. We developed a multiplexed and high-content screening assay using primary neurons and identified 67 small-molecule modulators of neuronal mitostasis (MnMs). Most MnMs that increased mitochondrial content, length, and/or health also increased mitochondrial function without altering neurite outgrowth. A subset of MnMs protected mitochondria in primary neurons from Aβ(1–42) toxicity, glutamate toxicity, and increased oxidative stress. Some MnMs were shown to directly target mitochondria. The top MnM also increased the synaptic activity of hippocampal neurons and proved to be potent in vivo, increasing the respiration rate of brain mitochondria after administering the compound to mice. Our results offer a platform that directly queries mitostasis processes in neurons, a collection of small-molecule modulators of mitochondrial dynamics and function, and candidate molecules for mitotherapeutics.

scholarly journals Corticotropin-releasing hormone (CRH) alters mitochondrial morphology and function by activating the NF-kB-DRP1 axis in hippocampal neurons

2020 ◽  
Vol 11 (11) ◽  
Author(s):  
Chiara R. Battaglia ◽  
Silvia Cursano ◽  
Enrico Calzia ◽  
Alberto Catanese ◽  
Tobias M. Boeckers
Keyword(s):  
Hippocampal Neurons ◽  
Morphological Changes ◽  
Mitochondrial Dynamics ◽  
Synaptic Activity ◽  
Mitochondrial Activity ◽  
Mitochondrial Morphology ◽  
Significant Shift ◽  
Corticotropin Releasing Hormone ◽  
Releasing Hormone

AbstractNeuronal stress-adaptation combines multiple molecular responses. We have previously reported that thorax trauma induces a transient loss of hippocampal excitatory synapses mediated by the local release of the stress-related hormone corticotropin-releasing hormone (CRH). Since a physiological synaptic activity relies also on mitochondrial functionality, we investigated the direct involvement of mitochondria in the (mal)-adaptive changes induced by the activation of neuronal CRH receptors 1 (CRHR1). We observed, in vivo and in vitro, a significant shift of mitochondrial dynamics towards fission, which correlated with increased swollen mitochondria and aberrant cristae. These morphological changes, which are associated with increased NF-kB activity and nitric oxide concentrations, correlated with a pronounced reduction of mitochondrial activity. However, ATP availability was unaltered, suggesting that neurons maintain a physiological energy metabolism to preserve them from apoptosis under CRH exposure. Our findings demonstrate that stress-induced CRHR1 activation leads to strong, but reversible, modifications of mitochondrial dynamics and morphology. These alterations are accompanied by bioenergetic defects and the reduction of neuronal activity, which are linked to increased intracellular oxidative stress, and to the activation of the NF-kB/c-Abl/DRP1 axis.

Sign in / Sign up

Export Citation Format

Share Document