Organization and properties of GABAergic neurons in solitary tract nucleus (NTS)

Timothy W. Bailey, Suzanne M. Appleyard, Young Ho Jin, Michael Andresen

Research output: Contribution to journalArticle

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Abstract

Cranial visceral afferents enter the brain at the solitary tract nucleus (NTS). GABAergic neurons are scattered throughout the NTS, but their relation to solitary tract (ST) afferent pathways is imprecisely known. We hypothesized that most GABAergic NTS neurons would be connected only indirectly to the ST. We identified GABAergic neurons in brain stem horizontal slices using transgenic mice in which enhanced green fluorescent protein (EGFP) expression was linked to glutamic acid decarboxylase expression (GAD+). Finely graded electrical shocks to ST recruit ST-synchronized synaptic events with all-or-none thresholds and individual waveforms did not change with greater suprathreshold intensities - evidence consistent with initiation by single afferent axons. Most (∼70%) GAD+ neurons received ST-evoked excitatory postsynaptic currents (EPSCs) that had minimally variant latencies (jitter, SD of latency 200 μs including inhibitory postsynaptic currents (IPSCs), indicating indirect connections (polysynaptic). Shocks of suprathreshold intensity delivered adjacent (50-300 μm) to the ST failed to excite non-ST inputs to second-order neurons, suggesting a paucity of axons passing near to ST that connected to these neurons. Despite expectations, we found similar ST synaptic patterns in GAD + and unlabeled neurons. Generally, ST information that arrived indirectly had small amplitudes (EPSCs and IPSCs) and frequency-dependent failures that reached >50% for IPSCs to bursts of stimuli. This ST afferent pathway organization is strongly use-dependent - a property that may tune signal propagation within and beyond NTS.

Original languageEnglish (US)
Pages (from-to)1712-1722
Number of pages11
JournalJournal of Neurophysiology
Volume99
Issue number4
DOIs
StatePublished - Apr 2008

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GABAergic Neurons
Solitary Nucleus
Inhibitory Postsynaptic Potentials
Afferent Pathways
Neurons
Excitatory Postsynaptic Potentials
Axons
Shock
Visceral Afferents
Glutamate Decarboxylase
Transgenic Mice
Brain Stem
Brain

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

Organization and properties of GABAergic neurons in solitary tract nucleus (NTS). / Bailey, Timothy W.; Appleyard, Suzanne M.; Jin, Young Ho; Andresen, Michael.

In: Journal of Neurophysiology, Vol. 99, No. 4, 04.2008, p. 1712-1722.

Research output: Contribution to journalArticle

Bailey, Timothy W. ; Appleyard, Suzanne M. ; Jin, Young Ho ; Andresen, Michael. / Organization and properties of GABAergic neurons in solitary tract nucleus (NTS). In: Journal of Neurophysiology. 2008 ; Vol. 99, No. 4. pp. 1712-1722.
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