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Inhibitory glial modulation of excitatory neurotransmission is reduced in nucleus tractus solitarius (NTS) of rats after short‐term sustained hypoxia
Author(s) -
AccorsiMendonca Daniela,
Bonagamba Leni GH,
Machado Benedito H.
Publication year - 2016
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.30.1_supplement.1232.1
Subject(s) - excitatory postsynaptic potential , neurotransmission , inhibitory postsynaptic potential , chemistry , endocrinology , agonist , medicine , patch clamp , neuroscience , electrophysiology , biology , receptor
During hypoxia condition the peripheral chemoreflex is activated and induces autonomic and respiratory responses. In this study we analyzed the effect of short‐term sustained hypoxia [(SH) 24 hours, FIO 2 10%] on the synaptic transmission of NTS. Using brainstem slices and whole‐cell patch clamp we observed that passive properties of NTS astrocytes were not affected by SH [input resistance: control: 44.5 ± 14 MΩ (n=8) vs SH: 31.5 ± 10 MΩ (n=4)][RMP control: −84 ± 3.6 mV (n=10) vs SH: −75 ± 5.2 mV (n=7)]. Since protease‐activated receptors 1 (PAR1) are found only in NTS astrocytes and not in neurons, we also evaluated the glial modulation on neurotransmission by activation of astrocytes with SFLLRN‐NH2 (PAR1 agonist, 20 μM). The SFLLRN‐NH2 decreased the amplitude of evoked excitatory post‐synaptic currents (eEPSCs) in NTS neurons from SH animals to values similar to the control group [control: −51 ± 5 pA (n=3) vs SH: −56 ± 8 pA (n=5)]. SFLLRN‐NH2 did not change the RMP of NTS neurons in both groups [control: aCSF: −65.5 ± 1.5 mV vs aCSF + SFLLRN‐NH2: −61 ± 5 mV, (n=4); SH: aCSF: −63 ± 5 vs aCSF + SFLLRN‐NH2: −56 ± 8 mV, (n=4)]. In addition, using in vivo labeling and multi‐photon microscopy, we observed that SH decreased the cellular density of astrocytes in NTS [control: 0.003 ± 0.0004 (n=5) vs SH: 0.001 ± 0.0001 cells / μm 2 (n=5)]. In conclusion, SH decreased the number of astrocytes and their inhibitory modulation on excitatory transmission on the NTS neurons. Support or Funding Information Financial support: FAPESP and CNPq.