In Vitro Properties of Neurons in the Rat Pretectal Nucleus of the Optic Tract

2007 ◽  
Vol 97 (5) ◽  
pp. 3574-3584 ◽  
Author(s):  
N. Prochnow ◽  
P. Lee ◽  
W. C. Hall ◽  
M. Schmidt
Keyword(s):  
Fluorescent Dyes ◽  
Optic Tract ◽  
Cell Populations ◽  
Patch Clamp Recording ◽  
Visual Activity ◽  
Optokinetic Reflex ◽  
Whole Cell Patch Clamp ◽  
Pretectal Nucleus ◽  
Efferent Projections

The nucleus of the optic tract (NOT) has been implicated in the initiation of the optokinetic reflex (OKR) and in the modulation of visual activity during saccades. The present experiments demonstrate that these two functions are served by separate cell populations that can be distinguished by differences in both their cellular physiology and their efferent projections. We compared the response properties of NOT cells in rats using target-directed whole cell patch-clamp recording in vitro. To identify the cells at the time of the recording experiments, they were prelabeled by retrograde axonal transport of WGA-apo-HRP-gold (15 nm), which was injected into their primary projection targets, either the ipsilateral superior colliculus (iSC), or the contralateral NOT (cNOT), or the ipsilateral inferior olive (iIO). Retrograde labeling after injections in single animals of either WGA-apo-HRP-gold with different particle sizes (10 and 20 nm) or two different fluorescent dyes distinguished two NOT cell populations. One projects to both the iSC and cNOT. These cells are spontaneously active in vitro and respond to intracellular depolarizations with temporally regular tonic firing. The other population projects to the iIO and consists of cells that show no spontaneous activity, respond phasically to intracellular depolarization, and show irregular firing patterns. We propose that the spontaneously active pathway to iSC and cNOT is involved in modulating the level of visual activity during saccades and that the phasically active pathway to iIO provides a short-latency relay from the retina to premotor mechanisms involved in reducing retinal slip.

scholarly journals Morphine-induced synaptic plasticity in the VTA is reversed by HDAC inhibition

2016 ◽  
Vol 116 (3) ◽  
pp. 1093-1103 ◽  
Author(s):  
Michael E. Authement ◽  
Ludovic D. Langlois ◽  
Haifa Kassis ◽  
Shawn Gouty ◽  
Matthieu Dacher ◽  
...  
Keyword(s):  
Behavioral Plasticity ◽  
Drugs Of Abuse ◽  
Patch Clamp Recording ◽  
Whole Cell Patch Clamp ◽  
Synaptic Changes ◽  
Induced Changes ◽  
And Behavior ◽  
H3 Acetylation

Dopamine (DA) dysfunction originating from the ventral tegmental area (VTA) occurs as a result of synaptic abnormalities following consumption of drugs of abuse and underlies behavioral plasticity associated with drug abuse. Drugs of abuse can cause changes in gene expression through epigenetic mechanisms in the brain that underlie some of the lasting neuroplasticity and behavior associated with addiction. Here we investigated the function of histone acetylation and histone deacetylase (HDAC)2 in the VTA in recovery of morphine-induced synaptic modifications following a single in vivo exposure to morphine. Using a combination of immunohistochemistry, Western blot, and whole cell patch-clamp recording in rat midbrain slices, we show that morphine increased HDAC2 activity in VTA DA neurons and reduced histone H3 acetylation at lysine 9 (Ac-H3K9) in the VTA 24 h after the injection. Morphine-induced synaptic changes at glutamatergic synapses involved endocannabinoid signaling to reduce GABAergic synaptic strength onto VTA DA neurons. Both plasticities were recovered by in vitro incubation of midbrain slices with a class I-specific HDAC inhibitor (HDACi), CI-994, through an increase in acetylation of histone H3K9. Interestingly, HDACi incubation also increased levels of Ac-H3K9 and triggered GABAergic and glutamatergic plasticities in DA neurons of saline-treated rats. Our results suggest that acute morphine-induced changes in VTA DA activity and synaptic transmission engage HDAC2 activity locally in the VTA to maintain synaptic modifications through histone hypoacetylation.

scholarly journals Functional and Pharmacological Evaluation of a Novel SCN2A Variant Linked to Early-onset Epilepsy

2020 ◽  
Author(s):  
Scott K. Adney ◽  
John J. Millichap ◽  
Jean-Marc DeKeyser ◽  
Tatiana Abramova ◽  
Christopher H. Thompson ◽  
...  
Keyword(s):  
Drug Response ◽  
Time Course ◽  
Voltage Dependence ◽  
De Novo ◽  
Patch Clamp Recording ◽  
Variants Of Unknown Significance ◽  
Whole Cell Patch Clamp ◽  
Genetic Features ◽  
Resurgent Current

ABSTRACTObjectiveWe identified a novel de novo SCN2A variant (M1879T) associated with infantile-onset epilepsy that responded dramatically to sodium channel blocker antiepileptic drugs. We analyzed the functional and pharmacological consequences of this variant to establish pathogenicity, and to correlate genotype with phenotype and clinical drug response.MethodsThe clinical and genetic features of an infant boy with epilepsy are presented. We investigated the effect of the variant using heterologously expressed recombinant human NaV1.2 channels. We performed whole-cell patch clamp recording to determine the functional consequences and response to carbamazepine.ResultsThe M1879T variant caused disturbances in channel inactivation including substantially depolarized voltage-dependence of inactivation, slower time course of inactivation, and enhanced resurgent current that collectively represent a gain-of-function. Carbamazepine partially normalized the voltage-dependence of inactivation and produced use-dependent block of the variant channel at high pulsing frequencies. Carbamazepine also suppresses resurgent current conducted by M1879T channels, but this effect was explained primarily by reducing the peak transient current. Molecular modeling suggests that the M1879T variant disrupts contacts with nearby residues in the C-terminal domain of the channel.InterpretationOur study demonstrates the value of conducting functional analyses of SCN2A variants of unknown significance to establish pathogenicity and genotype-phenotype correlations. We also show concordance of in vitro pharmacology using heterologous cells with the drug response observed clinically in a case of SCN2A-associated epilepsy.

Modulatory effects of 5-hydroxytryptamine on voltage-activated currents in cultured antennal lobe neurones of the sphinx moth Manduca sexta.

1995 ◽  
Vol 198 (3) ◽  
pp. 613-627 ◽  
Author(s):  
A R Mercer ◽  
J H Hayashi ◽  
J G Hildebrand
Keyword(s):  
Manduca Sexta ◽  
Adult Development ◽  
Antennal Lobe ◽  
Ionic Currents ◽  
Delayed Rectifier ◽  
Patch Clamp Recording ◽  
Whole Cell Patch Clamp ◽  
K Current ◽  
Reversible Reduction

The modulatory effects of 5-hydroxytryptamine (5-HT or serotonin) on voltage-gated currents in central olfactory neurones of the moth Manduca sexta have been examined in vitro using whole-cell patch-clamp recording techniques. Central olfactory neurones were dissociated from the antennal lobes of animals at stage 5 of the 18 stages of metamorphic adult development. The modulatory actions of 5-HT on voltage-activated ionic currents were examined in a subset of morphologically identifiable antennal lobe neurones maintained for 2 weeks in primary cell culture. 5-HT caused reversible reduction of both a rapidly activating A-type K+ current and a relatively slowly activating K+ current resembling a delayed rectifier-type conductance. 5-HT also reduced the magnitude of voltage-activated Ca2+ influx in these cells. The functional significance of 5-HT-modulation of central neurones is discussed.

An important functional role of persistent Na+ current in carotid body hypoxia transduction

2006 ◽  
Vol 101 (4) ◽  
pp. 1076-1084 ◽  
Author(s):  
Edward Vincent S. Faustino ◽  
David F. Donnelly
Keyword(s):  
Carotid Body ◽  
Acute Hypoxia ◽  
Whole Body ◽  
Conduction Time ◽  
Afferent Neurons ◽  
Patch Clamp Recording ◽  
Peripheral Chemoreceptor ◽  
Whole Cell Patch Clamp ◽  
Old Rats

Systemic hypoxia in mammals is sensed and transduced by the carotid body into increased action potential (AP) frequency on the sinus nerve, resulting in increased ventilation. The mechanism of hypoxia transduction is not resolved, but previous work suggested that fast Na+ channels play an important role in determining the rate and timing of APs (Donnelly, DF, Panisello JM, and Boggs D. J Physiol. 511: 301–311, 1998). We speculated that Na+ channel activity between APs, termed persistent Na+ current ( INaP), is responsible for AP generation that and riluzole and phenytoin, which inhibit this current, would impair organ function. Using whole cell patch clamp recording of intact petrosal neurons with projections to the carotid body, we demonstrated that INaP is present in chemoreceptor afferent neurons and is inhibited by riluzole. Furthermore, discharge frequencies of single-unit, chemoreceptor activity, in vitro, during normoxia (Po2 150 Torr) and during acute hypoxia (Po2 90 Torr) were significantly reduced by riluzole concentrations at or above 5 μM, and by phenytoin at 100 μM, without significant affect on nerve conduction time, AP magnitude (inferred from extracellular field), and AP duration. The effect of both drugs appeared solely postsynaptic because hypoxia-induced catecholamine release in the carotid body was not altered by either drug. The respiratory response of unanesthetized, unrestrained 2-wk-old rats to acute hypoxia (12% inspired O2 fraction), which was measured with whole body plethysmography, was significantly reduced after treatment with riluzole (2 mg/kg ip) and phenytoin (20 mg/kg ip). We conclude that INaP is present in chemoreceptor afferent neurons and serves an important role in peripheral chemoreceptor function and, hence, in the ventilatory response to hypoxia.

Early anoxia-induced vesicular glutamate release results from mobilization of calcium from intracellular stores

1993 ◽  
Vol 70 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. N. Katchman ◽  
N. Hershkowitz
Keyword(s):  
Calcium Influx ◽  
Glutamate Release ◽  
Hippocampal Slices ◽  
Calcium Currents ◽  
Patch Clamp Recording ◽  
Ca1 Neurons ◽  
Whole Cell Patch Clamp ◽  
Mepsc Frequency ◽  
Synaptic Changes

1. The cause of the increased frequency of glutamatergic miniature excitatory postsynaptic currents (mEPSCs) resulting from anoxia was investigated in CA1 neurons of the in vitro rat hippocampal slice. These neurons were examined by whole-cell patch-clamp recording, and hypoxia was induced by switching the perfusion of the slice from oxygenated artificial cerebral spinal fluid (ACSF) to ACSF saturated with 95% N2-5% O2. Except where noted, experiments were carried out in ACSF containing 1 microM tetrodotoxin (TTX). 2. Although anoxia resulted in a significant increase in the frequency of mEPSCs, the amplitude, rise time, and half-decay time of the mEPSCs were unchanged. This increase in frequency indicates that there is a change in presynaptic neurotransmitter release mechanisms, probably an increase in calcium concentration, soon after the onset of anoxia. The unchanged kinetics and amplitude of the mEPSCs indicate that anoxic-induced synaptic changes are not a result of changes in the postsynaptic glutamate receptor. 3. When hippocampal slices were exposed to anoxic conditions in ACSF with calcium excluded, an increase in mEPSC frequency equal to that in normal ACSF was observed. When 0.2 mM of CdCl2 was added to the zero-calcium ACSF, anoxia still resulted in increases in mEPSC frequency equal to those of normal ACSF. It is therefore concluded that the anoxia-induced increase in mEPSC frequency does not result from an increase in a transmembrane calcium influx. The zero-calcium plus 0.2 mM CdCl2 ACSF solution completely abolished orthodromically elicited synaptic potential (in the absence of TTX), indicating that calcium currents that mediate normal orthodromic transmitter release were completely abolished in the latter experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Reduced GABAergic transmission in the ventrobasal thalamus contributes to thermal hyperalgesia in chronic inflammatory pain

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Chan Zhang ◽  
Rong-Xiang Chen ◽  
Yu Zhang ◽  
Jie Wang ◽  
Feng-Yu Liu ◽  
...  
Keyword(s):  
Inflammatory Pain ◽  
Thermal Hyperalgesia ◽  
Thalamic Reticular Nucleus ◽  
Reticular Nucleus ◽  
Patch Clamp Recording ◽  
Gabaergic Transmission ◽  
Chronic Inflammatory Pain ◽  
Whole Cell Patch Clamp ◽  
Ventrobasal Thalamus

Abstract The ventrobasal (VB) thalamus is innervated by GABAergic afferents from the thalamic reticular nucleus (TRN) and participates in nociception. But how the TRN-VB pathway regulates pain is not fully understood. In the present study, we reported decreased extracellular GABA levels in the VB of rats with CFA-induced chronic inflammatory pain, measured by microdialysis with HPLC analysis. In vitro whole-cell patch-clamp recording showed decreased amplitudes of tonic currents, increased frequencies of mIPSCs, and increased paired-pulse ratios in thalamic slices from chronic inflammatory rats (7 days). Microinjection of the GABAAR agonist muscimol and optogenetic activation of the TRN-VB pathway relieved thermal hyperalgesia in chronic inflammatory pain. By contrast, microinjecting the extrasynaptic GABAAR agonist THIP or selective knockout of synaptic GABAAR γ2 subunits aggravated thermal hyperalgesia in the chronic stage of inflammatory pain. Our findings indicate that reduced GABAergic transmission in the VB contributes to thermal hyperalgesia in chronic inflammatory pain, which could be a synaptic target for pharmacotherapy.

Organization of the Intermediate Gray Layer of the Superior Colliculus. I. Intrinsic Vertical Connections

2004 ◽  
Vol 91 (4) ◽  
pp. 1706-1715 ◽  
Author(s):  
Matthew C. Helms ◽  
Gülden Özen ◽  
William C. Hall
Keyword(s):  
Superior Colliculus ◽  
Superficial Layer ◽  
Wide Field ◽  
Visually Guided ◽  
Patch Clamp Recording ◽  
Visuomotor Integration ◽  
Whole Cell Patch Clamp ◽  
Spatial Attributes ◽  
Caged Glutamate

A pathway from the superficial visual layers to the intermediate premotor layers of the superior colliculus has been proposed to mediate visually guided orienting movements. In these experiments, we combined photostimulation using “caged” glutamate with in vitro whole cell patch-clamp recording to demonstrate this pathway in the rat. Photostimulation in the superficial gray and optic layers (SGS and SO, respectively) evoked synaptic responses in intermediate gray layer (SGI) cells. The responses comprised individual excitatory postsynaptic currents (EPSCs) or EPSC clusters. Blockade of these EPSCs by TTX confirmed that they were synaptically mediated. Stimulation within a column (∼500 μm diam) extending superficially from the recorded cell evoked the largest and most reliable responses, but off-axis stimuli were effective as well. The EPSCs could be evoked by stimuli 1,000 μm off-axis from the postsynaptic neuron. The dimensions of this wider region (∼2 mm diam) corresponded to those of the dendrites of superficial layer wide-field neurons. SGI neurons differed in their input from SGS and SO; neurons in the middle of the intermediate layer (SGIb) were less likely to respond to visual layer photostimulation than were those in sublayers just above and below them. However, focal stimulation within SGIa did evoke responses within SGIb, indicating that SGIb neurons may receive input from the visual layers indirectly. These results demonstrate a columnar pathway that may mediate visually guided orienting movements, but the results also reveal spatial attributes of the pathway which imply that it also plays a more complex role in visuomotor integration.

Two populations of sympathetic neurons project selectively to mesenteric artery or vein

1999 ◽  
Vol 276 (4) ◽  
pp. H1263-H1272 ◽  
Author(s):  
Kirsteen N. Browning ◽  
Zhongling Zheng ◽  
David L. Kreulen ◽  
R. Alberto Travagli
Keyword(s):  
Mesenteric Artery ◽  
Sympathetic Neurons ◽  
Mesenteric Arteries ◽  
Patch Clamp Recording ◽  
Mesenteric Veins ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp ◽  
Mesenteric Ganglion ◽  
Two Populations

The objective of this study was to determine whether sympathetic neurons of the inferior mesenteric ganglion (IMG) projecting to mesenteric arteries could be distinguished by their localization, neurochemical phenotype, and electrophysiological properties from neurons projecting to mesenteric veins. In an in vitro intact vasculature-IMG preparation, neurons were labeled following intraluminal injection of Fluoro-Gold or rhodamine beads into the inferior mesenteric artery (IMA) or vein (IMV). The somata of neurons projecting to IMA were localized in the central part of the IMG, whereas those projecting to IMV were localized more peripherally. None of the labeled neurons was doubly labeled. Neuropeptide Y immunoreactivity was found in 18.9% of neurons innervating the IMA, but not in neurons innervating the IMV. Identified neurons were dissociated and characterized using whole cell patch-clamp recording. After direct soma depolarization, all of the labeled arterial and venous neurons were classified as tonic firing, compared with only 40% of unlabeled neurons; the remaining 60% of unlabeled neurons were phasic firing. The results indicate that IMG neurons projecting to mesenteric arteries are distinct from neurons projecting to mesenteric veins.

Bone Marrow Niches for Skeletal Progenitor Cells and their Inhabitants in Health and Disease

2019 ◽  
Vol 14 (4) ◽  
pp. 305-319 ◽  
Author(s):  
Marietta Herrmann ◽  
Franz Jakob
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Adult Stem Cells ◽  
Current Knowledge ◽  
Cell Populations ◽  
Surface Markers ◽  
Bone Marrow Niches

The bone marrow hosts skeletal progenitor cells which have most widely been referred to as Mesenchymal Stem or Stromal Cells (MSCs), a heterogeneous population of adult stem cells possessing the potential for self-renewal and multilineage differentiation. A consensus agreement on minimal criteria has been suggested to define MSCs in vitro, including adhesion to plastic, expression of typical surface markers and the ability to differentiate towards the adipogenic, osteogenic and chondrogenic lineages but they are critically discussed since the differentiation capability of cells could not always be confirmed by stringent assays in vivo. However, these in vitro characteristics have led to the notion that progenitor cell populations, similar to MSCs in bone marrow, reside in various tissues. MSCs are in the focus of numerous (pre)clinical studies on tissue regeneration and repair.Recent advances in terms of genetic animal models enabled a couple of studies targeting skeletal progenitor cells in vivo. Accordingly, different skeletal progenitor cell populations could be identified by the expression of surface markers including nestin and leptin receptor. While there are still issues with the identity of, and the overlap between different cell populations, these studies suggested that specific microenvironments, referred to as niches, host and maintain skeletal progenitor cells in the bone marrow. Dynamic mutual interactions through biological and physical cues between niche constituting cells and niche inhabitants control dormancy, symmetric and asymmetric cell division and lineage commitment. Niche constituting cells, inhabitant cells and their extracellular matrix are subject to influences of aging and disease e.g. via cellular modulators. Protective niches can be hijacked and abused by metastasizing tumor cells, and may even be adapted via mutual education. Here, we summarize the current knowledge on bone marrow skeletal progenitor cell niches in physiology and pathophysiology. We discuss the plasticity and dynamics of bone marrow niches as well as future perspectives of targeting niches for therapeutic strategies.

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