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  1. Article ; Online: Glutamate Spillover Dynamically Strengthens Gabaergic Synaptic Inhibition of the Hypothalamic Paraventricular Nucleus.

    Yamaguchi, Junya / Andrade, Mary Ann / Truong, Tamara T / Toney, Glenn M

    The Journal of neuroscience : the official journal of the Society for Neuroscience

    2024  Volume 44, Issue 7

    Abstract: The hypothalamic paraventricular nucleus (PVN) is strongly inhibited by γ-aminobutyric acid (GABA) from the surrounding peri-nuclear zone (PNZ). Because glutamate mediates fast excitatory transmission and is substrate for GABA synthesis, we tested its ... ...

    Abstract The hypothalamic paraventricular nucleus (PVN) is strongly inhibited by γ-aminobutyric acid (GABA) from the surrounding peri-nuclear zone (PNZ). Because glutamate mediates fast excitatory transmission and is substrate for GABA synthesis, we tested its capacity to dynamically strengthen GABA inhibition. In PVN slices from male mice, bath glutamate applied during ionotropic glutamate receptor blockade increased PNZ-evoked inhibitory postsynaptic currents (eIPSCs) without affecting GABA-A receptor agonist currents or single-channel conductance, implicating a presynaptic mechanism(s). Consistent with this interpretation, bath glutamate failed to strengthen IPSCs during pharmacological saturation of GABA-A receptors. Presynaptic analyses revealed that glutamate did not affect paired-pulse ratio, peak eIPSC variability, GABA vesicle recycling speed, or readily releasable pool (RRP) size. Notably, glutamate-GABA strengthening (GGS) was unaffected by metabotropic glutamate receptor blockade and graded external Ca
    MeSH term(s) Male ; Mice ; Animals ; Paraventricular Hypothalamic Nucleus/metabolism ; Glutamic Acid/metabolism ; Neurons/physiology ; gamma-Aminobutyric Acid/metabolism ; Neuroglia/metabolism ; Synaptic Transmission/physiology
    Chemical Substances Glutamic Acid (3KX376GY7L) ; gamma-Aminobutyric Acid (56-12-2)
    Language English
    Publishing date 2024-02-14
    Publishing country United States
    Document type Journal Article
    ZDB-ID 604637-x
    ISSN 1529-2401 ; 0270-6474
    ISSN (online) 1529-2401
    ISSN 0270-6474
    DOI 10.1523/JNEUROSCI.1851-22.2023
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Oxytocin Receptor Activation Rescues Opioid-Induced Respiratory Depression by Systemic Fentanyl in the Rat.

    Brackley, Allison Doyle / Toney, Glenn M

    The Journal of pharmacology and experimental therapeutics

    2021  Volume 378, Issue 2, Page(s) 96–107

    Abstract: Opioid overdose intervention by naloxone, a high affinity receptor antagonist, reverses opioid-induced respiratory depression (OIRD) and analgesia by displacing opioids. Systemic naloxone stimulates release of the hypothalamic neuropeptide oxytocin, ... ...

    Abstract Opioid overdose intervention by naloxone, a high affinity receptor antagonist, reverses opioid-induced respiratory depression (OIRD) and analgesia by displacing opioids. Systemic naloxone stimulates release of the hypothalamic neuropeptide oxytocin, which has analgesic properties and participates in cardiorespiratory homeostasis. To test the hypothesis that oxytocin can reverse OIRD, we assessed the rescue potential of graded doses (0, 0.1, 2, 5, 10, 50 nmol/kg, i.v.) of oxytocin to counter fentanyl (60 nmol/kg, i.v.)-induced depression of neural inspiration indexed by recording phrenic nerve activity (PNA) in anesthetized (urethane/
    MeSH term(s) Animals ; Fentanyl ; Oxytocin ; Rats ; Receptors, Opioid ; Receptors, Oxytocin
    Chemical Substances Receptors, Opioid ; Receptors, Oxytocin ; Oxytocin (50-56-6) ; Fentanyl (UF599785JZ)
    Language English
    Publishing date 2021-05-14
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 3106-9
    ISSN 1521-0103 ; 0022-3565
    ISSN (online) 1521-0103
    ISSN 0022-3565
    DOI 10.1124/jpet.121.000535
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  3. Article ; Online: Presence of a remote fear memory engram in the central amygdala.

    Hammack, Robert J / Fischer, Victoria E / Andrade, Mary Ann / Toney, Glenn M

    Learning & memory (Cold Spring Harbor, N.Y.)

    2023  Volume 30, Issue 10, Page(s) 250–259

    Abstract: Fear memory formation and recall are highly regulated processes, with the central amygdala (CeA) contributing to fear memory-related behaviors. We recently reported that a remote fear memory engram is resident in the anterior basolateral amygdala (aBLA). ...

    Abstract Fear memory formation and recall are highly regulated processes, with the central amygdala (CeA) contributing to fear memory-related behaviors. We recently reported that a remote fear memory engram is resident in the anterior basolateral amygdala (aBLA). However, the extent to which downstream neurons in the CeA participate in this engram is unknown. We tested the hypothesis that CeA neurons activated during fear memory formation are reactivated during remote memory retrieval such that a CeA engram participates in remote fear memory recall and its associated behavior. Using contextual fear conditioning in TRAP2;Ai14 mice, we identified, by persistent Cre-dependent tdTomato expression (i.e., "TRAPing"), CeA neurons that were
    MeSH term(s) Mice ; Animals ; Central Amygdaloid Nucleus ; Memory/physiology ; Memory, Long-Term ; Fear/physiology ; Mental Recall/physiology
    Language English
    Publishing date 2023-10-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1204777-6
    ISSN 1549-5485 ; 1072-0502
    ISSN (online) 1549-5485
    ISSN 1072-0502
    DOI 10.1101/lm.053833.123
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  4. Article ; Online: Anterior basolateral amygdala neurons comprise a remote fear memory engram.

    Hammack, Robert J / Fischer, Victoria E / Andrade, Mary Ann / Toney, Glenn M

    Frontiers in neural circuits

    2023  Volume 17, Page(s) 1167825

    Abstract: Introduction: Threatening environmental cues often generate enduring fear memories, but how these are formed and stored remains actively investigated. Recall of a recent fear memory is thought to reflect reactivation of neurons, in multiple brain ... ...

    Abstract Introduction: Threatening environmental cues often generate enduring fear memories, but how these are formed and stored remains actively investigated. Recall of a recent fear memory is thought to reflect reactivation of neurons, in multiple brain regions, activated during memory formation, indicating that anatomically distributed and interconnected neuronal ensembles comprise fear memory engrams. The extent to which anatomically specific activation-reactivation engrams persist during long-term fear memory recall, however, remains largely unexplored. We hypothesized that principal neurons in the anterior basolateral amygdala (aBLA), which encode negative valence, acutely reactivate during remote fear memory recall to drive fear behavior.
    Methods: Using adult offspring of TRAP2 and Ai14 mice, persistent tdTomato expression was used to "TRAP" aBLA neurons that underwent Fos-activation during contextual fear conditioning (electric shocks) or context only conditioning (no shocks) (
    Results: TRAPed (tdTomato +), Fos +, and reactivated (double-labeled) neuronal ensembles were larger in fear- than context-conditioned mice, with the middle sub-region and middle/caudal dorsomedial quadrants of aBLA displaying the greatest densities of all three ensemble populations. Whereas tdTomato + ensembles were dominantly glutamatergic in context and fear groups, freezing behavior during remote memory recall was not correlated with ensemble sizes in either group.
    Discussion: We conclude that although an aBLA-inclusive fear memory engram forms and persists at a remote time point, plasticity impacting electrophysiological responses of engram neurons, not their population size, encodes fear memory and drives behavioral manifestations of long-term fear memory recall.
    MeSH term(s) Basolateral Nuclear Complex/cytology ; Basolateral Nuclear Complex/physiology ; Neurons/physiology ; Fear/physiology ; Memory, Long-Term/physiology ; Animals ; Mice ; Mice, Transgenic ; Conditioning, Operant ; Mental Recall/physiology ; Proto-Oncogene Proteins c-fos/genetics ; Gene Knock-In Techniques
    Chemical Substances Proto-Oncogene Proteins c-fos
    Language English
    Publishing date 2023-04-27
    Publishing country Switzerland
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2452968-0
    ISSN 1662-5110 ; 1662-5110
    ISSN (online) 1662-5110
    ISSN 1662-5110
    DOI 10.3389/fncir.2023.1167825
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  5. Article ; Online: Central AT1 receptor signaling by circulating angiotensin II is permissive to acute intermittent hypoxia-induced sympathetic neuroplasticity.

    Shimoura, Caroline G / Andrade, Mary Ann / Toney, Glenn M

    Journal of applied physiology (Bethesda, Md. : 1985)

    2020  Volume 128, Issue 5, Page(s) 1329–1337

    Abstract: Acute intermittent hypoxia (AIH) triggers sympathetic long-term facilitation (sLTF), a progressive increase in sympathetic nerve activity (SNA) linked to central AT1 receptor (AT1R) activation by circulating angiotensin II (ANG II). Here, we investigated ...

    Abstract Acute intermittent hypoxia (AIH) triggers sympathetic long-term facilitation (sLTF), a progressive increase in sympathetic nerve activity (SNA) linked to central AT1 receptor (AT1R) activation by circulating angiotensin II (ANG II). Here, we investigated AIH activation of the peripheral renin-angiotensin system (RAS) and the extent to which the magnitude of RAS activation predicts the magnitude of AIH-induced sLTF. In anesthetized male Sprague-Dawley rats, plasma renin activity (PRA) increased in a linear fashion in response to 5 (
    MeSH term(s) Angiotensin II/blood ; Animals ; Blood Pressure ; Hypoxia ; Losartan/pharmacology ; Male ; Neuronal Plasticity ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; Renin-Angiotensin System ; Sympathetic Nervous System
    Chemical Substances Receptor, Angiotensin, Type 1 ; Angiotensin II (11128-99-7) ; Losartan (JMS50MPO89)
    Language English
    Publishing date 2020-04-02
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 219139-8
    ISSN 1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
    ISSN (online) 1522-1601
    ISSN 0021-8987 ; 0161-7567 ; 8750-7587
    DOI 10.1152/japplphysiol.00094.2020
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  6. Article ; Online: Intermittent hypercapnic hypoxia induces respiratory hypersensitivity to fentanyl accompanied by tonic respiratory depression by endogenous opioids.

    Brackley, Allison D / Andrade, Mary Ann / Toney, Glenn M

    The Journal of physiology

    2020  Volume 598, Issue 15, Page(s) 3239–3257

    Abstract: Key points: Sleep apnoea increases susceptibility to opioid-induced respiratory depression (OIRD). Endogenous opioids are implicated as a contributing factor in sleep apnoea. Rats exposed to sleep-phase chronic intermittent hypercapnic hypoxia (CIHH) ... ...

    Abstract Key points: Sleep apnoea increases susceptibility to opioid-induced respiratory depression (OIRD). Endogenous opioids are implicated as a contributing factor in sleep apnoea. Rats exposed to sleep-phase chronic intermittent hypercapnic hypoxia (CIHH) for 7 days exhibited exaggerated OIRD to systemic fentanyl both while anaesthetized and artificially ventilated and while conscious and breathing spontaneously, implicating heightened CNS inhibitory efficacy of fentanyl. CIHH also induced tonic endogenous opioid suppression of neural inspiration. Sleep-related episodes of hypercapnic hypoxia, as in sleep apnoea, promote hypersensitivity to OIRD, with tonic respiratory depression by endogenous opioids implicated as a potential underlying cause.
    Abstract: Sleep apnoea (SA) increases opioid-induced respiratory depression (OIRD) and lethality. To test the hypothesis that this results from chronic intermittent bouts of hypercapnic hypoxia (CIHH) accompanying SA, we compared OIRD across continuously normoxic control rats and rats exposed to sleep-phase (8 h/day) CIHH for 1 week. OIRD sensitivity was first assessed in anaesthetized (urethane/α-chloralose), vagotomized and artificially ventilated rats by recording phrenic nerve activity (PNA) to index neural inspiration and quantify PNA burst inhibition to graded doses (0, 2, 20, 50 μg kg
    MeSH term(s) Analgesics, Opioid ; Animals ; Fentanyl/toxicity ; Hypoxia ; Rats ; Rats, Sprague-Dawley ; Respiratory Hypersensitivity ; Respiratory Insufficiency
    Chemical Substances Analgesics, Opioid ; Fentanyl (UF599785JZ)
    Language English
    Publishing date 2020-06-14
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 3115-x
    ISSN 1469-7793 ; 0022-3751
    ISSN (online) 1469-7793
    ISSN 0022-3751
    DOI 10.1113/JP280021
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  7. Article ; Online: Early central cardiovagal dysfunction after high fat diet in a murine model.

    Strain, Misty M / Espinoza, Liliana / Fedorchak, Stephanie / Littlejohn, Erica L / Andrade, Mary Ann / Toney, Glenn M / Boychuk, Carie R

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 6550

    Abstract: High fat diet (HFD) promotes cardiovascular disease and blunted cardiac vagal regulation. Temporal onset of loss of cardiac vagal control and its underlying mechanism are presently unclear. We tested our hypothesis that reduced central vagal regulation ... ...

    Abstract High fat diet (HFD) promotes cardiovascular disease and blunted cardiac vagal regulation. Temporal onset of loss of cardiac vagal control and its underlying mechanism are presently unclear. We tested our hypothesis that reduced central vagal regulation occurs early after HFD and contributes to poor cardiac regulation using cardiovascular testing paired with pharmacology in mice, molecular biology, and a novel bi-transgenic mouse line. Results show HFD, compared to normal fat diet (NFD), significantly blunted cardio/pulmonary chemoreflex bradycardic responses after 15 days, extending as far as tested (> 30 days). HFD produced resting tachycardia by day 3, reflected significant loss of parasympathetic tone. No differences in bradycardic responses to graded electrical stimulation of the distal cut end of the cervical vagus indicated diet-induced differences in vagal activity were centrally mediated. In nucleus ambiguus (NA), surface expression of δ-subunit containing type A gamma-aminobutyric acid receptors (GABA
    MeSH term(s) Mice ; Animals ; Disease Models, Animal ; Diet, High-Fat/adverse effects ; Medulla Oblongata/metabolism ; Vagus Nerve/physiology ; Bradycardia ; gamma-Aminobutyric Acid/metabolism
    Chemical Substances gamma-Aminobutyric Acid (56-12-2)
    Language English
    Publishing date 2023-04-21
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-32492-w
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  8. Article ; Online: Regulation of neuronal cell volume: from activation to inhibition to degeneration.

    Toney, Glenn M

    The Journal of physiology

    2010  Volume 588, Issue Pt 18, Page(s) 3347–3348

    MeSH term(s) Animals ; Apoptosis/physiology ; Cell Size ; Neurons/cytology ; Neurons/physiology ; Osmosis
    Language English
    Publishing date 2010-09-14
    Publishing country England
    Document type Introductory Journal Article
    ZDB-ID 3115-x
    ISSN 1469-7793 ; 0022-3751
    ISSN (online) 1469-7793
    ISSN 0022-3751
    DOI 10.1113/jphysiol.2010.197251
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  9. Article ; Online: Chronic intermittent hypoxia enhances glycinergic inhibition in nucleus tractus solitarius.

    Jia, Shuping / Rybalchenko, Nataliya / Kunwar, Kishor / Farmer, George E / Little, Joel T / Toney, Glenn M / Cunningham, J Thomas

    Journal of neurophysiology

    2022  Volume 128, Issue 6, Page(s) 1383–1394

    Abstract: Chronic intermittent hypoxia (CIH), an animal model of sleep apnea, has been shown to alter the activity of second-order chemoreceptor neurons in the caudal nucleus of the solitary tract (cNTS). Although numerous studies have focused on excitatory ... ...

    Abstract Chronic intermittent hypoxia (CIH), an animal model of sleep apnea, has been shown to alter the activity of second-order chemoreceptor neurons in the caudal nucleus of the solitary tract (cNTS). Although numerous studies have focused on excitatory plasticity, few studies have explored CIH-induced plasticity impacting inhibitory inputs to NTS neurons, and the roles of GABAergic and glycinergic inputs on heightened cNTS excitability following CIH are unknown. In addition, changes in astrocyte function may play a role in cNTS plasticity responses to CIH. This study tested the effects of a 7-day CIH protocol on miniature inhibitory postsynaptic currents (mIPSCs) in cNTS neurons receiving chemoreceptor afferents. Normoxia-treated rats primarily displayed GABA mIPSCs, whereas CIH-treated rats exhibited a shift toward combined GABA/glycine-mediated mIPSCs. CIH increased glycinergic mIPSC amplitude and area. This shift was not observed in dorsal motor nucleus of the vagus neurons or cNTS cells from females. Immunohistochemistry showed that strengthened glycinergic mIPSCs were associated with increased glycine receptor protein and were dependent on receptor trafficking in CIH-treated rats. In addition, CIH altered astrocyte morphology in the cNTS, and inactivation of astrocytes following CIH reduced glycine receptor-mediated mIPSC frequency and overall mIPSC amplitude. In cNTS, CIH produced changes in glycine signaling that appear to reflect increased trafficking of glycine receptors to the cell membrane. Increased glycine signaling in cNTS associated with CIH also appears to be dependent on astrocytes. Additional studies will be needed to determine how CIH influences glycine receptor expression and astrocyte function in cNTS.
    MeSH term(s) Rats ; Animals ; Solitary Nucleus/metabolism ; Receptors, Glycine/metabolism ; Rats, Sprague-Dawley ; Hypoxia ; Glycine/metabolism ; gamma-Aminobutyric Acid/metabolism ; Sleep Apnea Syndromes/metabolism ; Neural Inhibition/physiology
    Chemical Substances Receptors, Glycine ; Glycine (TE7660XO1C) ; gamma-Aminobutyric Acid (56-12-2)
    Language English
    Publishing date 2022-11-02
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 80161-6
    ISSN 1522-1598 ; 0022-3077
    ISSN (online) 1522-1598
    ISSN 0022-3077
    DOI 10.1152/jn.00241.2022
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  10. Article ; Online: High dietary salt amplifies osmoresponsiveness in vasopressin-releasing neurons.

    Levi, David I / Wyrosdic, Joshua C / Hicks, Amirah-Iman / Andrade, Mary Ann / Toney, Glenn M / Prager-Khoutorsky, Masha / Bourque, Charles W

    Cell reports

    2021  Volume 34, Issue 11, Page(s) 108866

    Abstract: High dietary salt increases arterial pressure partly through activation of magnocellular neurosecretory cells ( ... ...

    Abstract High dietary salt increases arterial pressure partly through activation of magnocellular neurosecretory cells (MNC
    MeSH term(s) Angiotensin II ; Animals ; Cell Membrane/drug effects ; Cell Membrane/metabolism ; Cytoskeleton/drug effects ; Cytoskeleton/metabolism ; Disease Models, Animal ; Excitatory Postsynaptic Potentials/drug effects ; Hypertension/pathology ; Male ; Mechanotransduction, Cellular/drug effects ; Neurons/drug effects ; Neurons/metabolism ; Osmosis ; Probability ; Rats, Wistar ; Sodium Chloride, Dietary/adverse effects ; Synapses/drug effects ; Synapses/metabolism ; Vasopressins/metabolism ; Rats
    Chemical Substances Sodium Chloride, Dietary ; Vasopressins (11000-17-2) ; Angiotensin II (11128-99-7)
    Language English
    Publishing date 2021-04-16
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2649101-1
    ISSN 2211-1247 ; 2211-1247
    ISSN (online) 2211-1247
    ISSN 2211-1247
    DOI 10.1016/j.celrep.2021.108866
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