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Post‐synaptic effects of Group II metabotropic glutamate receptors (mGluRs) on second‐order baroreceptor neurons of the nucleus tractus solitarius (NTS) in rats
Author(s) -
Sekizawa Shinichi,
Hoffman Matthew,
Bonham Ann C.
Publication year - 2008
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.22.1_supplement.1171.13
Subject(s) - metabotropic glutamate receptor , chemistry , bicuculline , glutamate receptor , baroreceptor , metabotropic receptor , inhibitory postsynaptic potential , neurotransmission , nbqx , ionotropic effect , postsynaptic potential , neuroscience , stimulation , gabaa receptor , medicine , endocrinology , receptor , ampa receptor , biology , heart rate , biochemistry , blood pressure
In vivo and in vitro studies have suggested that Group II mGluRs have complex presynaptic effects on baroreceptor signal transmission in the NTS, heterosynaptically depressing both glutamate and GABA release. Here, we tested the effects of postsynaptic Group II mGluR activation by agonists (L‐CCG‐1, 10 μ M or LY379268 ,100 nM) and by endogenous glutamate release (TS stimulation) on functionally‐identified second‐order baroreceptor neurons in a brainstem slice with blockade of ionotropic GluRs (NBQX, 10 μ M & AP5, 50 μM) and GABA‐A‐Rs (bicuculline, 10 μ M). At concentrations selective for mGluR Group II activation as shown by blockade by the mGuR, antagonist, LY341495 (0.2 – 1 μM), the agonists, LY379268 and L‐CCG‐1 (10 μM) hyperpolarized the membrane potential (−10 ± 1.2 mV, n = 24, and −6.5 ± 1.0 mV, n = 16, respectively). Under these same conditions, TS stimulation (6 paired stimuli/s) also induced a hyperpolarization (−5.1 ± 0.5 mV; n = 3). LY379268 ‐induced hyperpolarization was decreased with a nonhydrolyzableGDP analog, GDP‐β‐S in the patch pipette by 72 ± 6.9 % (p < 0.05, n = 7), indicating G‐protein participation. The data suggest that mGluR Group II receptors may modulate baroreceptor signal transmission by postsynaptic effects in addition to presynaptic effects on glutamate and GABA release at the first synapses in the baroreceptor central network.