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Synaptic and neurochemical characteristics of the nucleus tractus solitarius pars centralis neurons (1129.7)
Author(s) -
Babic Tanja,
Browning Kirsteen,
Travagli R. Alberto
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1129.7
Subject(s) - neurochemical , excitatory postsynaptic potential , chemistry , neuroscience , patch clamp , postsynaptic current , postsynaptic potential , solitary nucleus , neurotransmission , medicine , endocrinology , electrophysiology , nucleus , biology , inhibitory postsynaptic potential , receptor , biochemistry
The nucleus tractus solitarius (NTS) receives gastrointestinal (GI), cardiovascular and respiratory visceral sensory information via A or C‐fibers. We have shown recently that, contrary to cardiovascular NTSmedialis neurons, the majority of esophageal NTScentralis (cNTS) neurons respond to vanilloid agonists while only a small subset responds to both vanilloid and purinerigic agonists. The aim of this study was to investigate further the neurochemical and synaptic characteristics of cNTS neurons using whole cell patch clamp and single cell RT‐PCR. Excitatory postsynaptic currents (EPSCs) were evoked in cNTS by tractus solitarius stimulation. Perfusion of the slices with αβ‐methylene ATP (αMeATP) increased the amplitude of the evoked EPSC in 9 of 23 neurons tested. Variance‐mean (V‐M) analysis was performed to determine synaptic characteristics of αMeATP‐responsive and non‐responsive neurons. αMeATP ‐responsive neurons had 40±16 release sites, quantal size was 21±9pA and 78±5% probability of release during perfusion with 2.4 mM [Ca2+]e. Conversely, non‐responsive neurons had 18±6 release sites, quantal size was 23±3pA and 75±4% probability of release at 2.4 mM [Ca2+]e. Single‐cell RT‐PCR revealed that 8/13 responsive neurons expressed mGluR8 mRNA, whereas only 3 expressed glutamic acid dehydroxylase (GAD). A significantly lower proportion of non‐responsive neurons expressed mGluR8 (2/30), whereas a greater proportion expressed GAD (12/30). These data demonstrate that cNTS comprises distinct sub‐populations of neurons that can be distinguished based on their responses to purinergic agonists and have distinct neurochemical and synaptic characteristics, suggesting that integration of sensory inputs from the esophagus relies on a discrete organization of synapses between vagal afferent fibers and cNTS neurons. Grant Funding Source : DK55530