Regulation of transmitter release by high-affinity group III mGluRs in the supraoptic nucleus of the rat hypothalamus.

Aude Panatier, Dominique A Poulain, Stéphane H.R Oliet
Neuropharmacology. 2004-09-01; 47(3): 333-341
DOI: 10.1016/j.neuropharm.2004.05.003

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1. Neuropharmacology. 2004 Sep;47(3):333-41.

Regulation of transmitter release by high-affinity group III mGluRs in the
supraoptic nucleus of the rat hypothalamus.

Panatier A(1), Poulain DA, Oliet SH.

Author information:
(1)Inserm U378, Institut François Magendie, Université Victor Segalen, 1, rue
Camille Saint Saëns, 33077 Bordeaux Cedex, France.

We analyzed the subtypes of group III metabotropic glutamate receptors (mGluRs)
modulating inhibitory and excitatory transmission in the rat supraoptic nucleus.
Bath application of the agonist l-AP4 at 200 microM, a concentration that
activates all group III mGluR subtypes, inhibited the frequency but not the
amplitude of miniature inhibitory and excitatory postsynaptic currents,
indicating a presynaptic site of action. l-AP4 at low concentrations (10 microM),
as well as ACPT-1 (50 microM), a specific mGluR III agonist, inhibited
transmission at GABAergic and glutamatergic synapses to the same extent as 200
microM l-AP4. Because the potency of l-AP4 and ACPT-1 is much higher on mGluR4
and mGluR8 than on mGluR7, these results are consistent with the presence of
high-affinity group III mGluRs regulating transmitter release in this nucleus. In
agreement with these findings, DCPG (30 microM), a selective mGluR8 agonist,
induced a significant depression of inhibitory and excitatory synaptic currents.
Group III mGluRs such as mGluR8, because of their high affinity for glutamate,
are particularly well suited to detect small changes in the concentration of this
excitatory amino acid in the extracellular space. Their presence, therefore, may
favor the negative feedback control exerted by glutamate on its own release as
well as the intersynaptic crosstalk mediated by glutamate spillover on adjacent
synapses.

DOI: 10.1016/j.neuropharm.2004.05.003
PMID: 15275822 [Indexed for MEDLINE]

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