Kainate receptors (KARs) are involved in both NMDA receptor-independent long-term potentiation (LTP) and synaptic facilitation at mossy fibre synapses in the CA3 region of the hippocampus. However, the identity of the KAR subtypes involved remains controversial. Here we used a highly potent and selective GluK1 (formerly GluR5) antagonist (ACET) to elucidate roles of GluK1-containing KARs in these synaptic processes. We confirmed that ACET is an extremely potent GluK1 antagonist, with a Kb value of 1.4+/-0.2 nM. In contrast, ACET was ineffective at GluK2 (formerly GluR6) receptors at all concentrations tested (up to 100 microM) and had no effect at GluK3 (formerly GluR7) when tested at 1 microM. The X-ray crystal structure of ACET bound to the ligand binding core of GluK1 was similar to the UBP310-GluK1 complex. In the CA1 region of hippocampal slices, ACET was effective at blocking the depression of both fEPSPs and monosynaptically evoked GABAergic transmission induced by ATPA, a GluK1 selective agonist. In the CA3 region of the hippocampus, ACET blocked the induction of NMDA receptor-independent mossy fibre LTP. To directly investigate the role of pre-synaptic GluK1-containing KARs we combined patch-clamp electrophysiology and 2-photon microscopy to image Ca2+ dynamics in individual giant mossy fibre boutons. ACET consistently reduced short-term facilitation of pre-synaptic calcium transients induced by 5 action potentials evoked at 20-25Hz. Taken together our data provide further evidence for a physiological role of GluK1-containing KARs in synaptic facilitation and LTP induction at mossy fibre-CA3 synapses.

ACET is a highly potent and specific kainate receptor antagonist: characterisation and effects on hippocampal mossy fibre function / S. L., Dargan; V. R., J.; G. M., Alushin; J. L., Sherwood; Nistico', ROBERT GIOVANNI; Z. A., Bortolotto; A. M., Ogden; D., Bleakman; A. J., Doherty; D., Lodge; M. L., Mayer; S. M., Fitzjohn; D. E., Jane; G. L., Collingridge. - In: NEUROPHARMACOLOGY. - ISSN 0028-3908. - 56:(2009), pp. 121-130. [10.1016/j.neuropharm.2008.08.016]

ACET is a highly potent and specific kainate receptor antagonist: characterisation and effects on hippocampal mossy fibre function.

NISTICO', ROBERT GIOVANNI;
2009

Abstract

Kainate receptors (KARs) are involved in both NMDA receptor-independent long-term potentiation (LTP) and synaptic facilitation at mossy fibre synapses in the CA3 region of the hippocampus. However, the identity of the KAR subtypes involved remains controversial. Here we used a highly potent and selective GluK1 (formerly GluR5) antagonist (ACET) to elucidate roles of GluK1-containing KARs in these synaptic processes. We confirmed that ACET is an extremely potent GluK1 antagonist, with a Kb value of 1.4+/-0.2 nM. In contrast, ACET was ineffective at GluK2 (formerly GluR6) receptors at all concentrations tested (up to 100 microM) and had no effect at GluK3 (formerly GluR7) when tested at 1 microM. The X-ray crystal structure of ACET bound to the ligand binding core of GluK1 was similar to the UBP310-GluK1 complex. In the CA1 region of hippocampal slices, ACET was effective at blocking the depression of both fEPSPs and monosynaptically evoked GABAergic transmission induced by ATPA, a GluK1 selective agonist. In the CA3 region of the hippocampus, ACET blocked the induction of NMDA receptor-independent mossy fibre LTP. To directly investigate the role of pre-synaptic GluK1-containing KARs we combined patch-clamp electrophysiology and 2-photon microscopy to image Ca2+ dynamics in individual giant mossy fibre boutons. ACET consistently reduced short-term facilitation of pre-synaptic calcium transients induced by 5 action potentials evoked at 20-25Hz. Taken together our data provide further evidence for a physiological role of GluK1-containing KARs in synaptic facilitation and LTP induction at mossy fibre-CA3 synapses.
2009
Action Potentials; drug effects/physiology, Alanine; analogs /&/ derivatives/chemistry/pharmacology, Animals, Calcium; metabolism, Cell Line; Transformed, Crystallography; X-Ray; methods, Dose-Response Relationship; Drug, Electric Stimulation; methods, Excitatory Amino Acid Agonists; chemistry/pharmacology, Excitatory Amino Acid Antagonists; pharmacology, Female, Hippocampus; cytology, Humans, Models; Molecular, Mossy Fibers; Hippocampal; drug effects, Pyramidal Cells; drug effects/physiology, Rats, Receptors; Kainic Acid; antagonists /&/ inhibitors/genetics, Synaptic Transmission; drug effects/physiology, Transfection, Uracil; analogs /&/ derivatives/chemistry/pharmacology
01 Pubblicazione su rivista::01a Articolo in rivista
ACET is a highly potent and specific kainate receptor antagonist: characterisation and effects on hippocampal mossy fibre function / S. L., Dargan; V. R., J.; G. M., Alushin; J. L., Sherwood; Nistico', ROBERT GIOVANNI; Z. A., Bortolotto; A. M., Ogden; D., Bleakman; A. J., Doherty; D., Lodge; M. L., Mayer; S. M., Fitzjohn; D. E., Jane; G. L., Collingridge. - In: NEUROPHARMACOLOGY. - ISSN 0028-3908. - 56:(2009), pp. 121-130. [10.1016/j.neuropharm.2008.08.016]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/514114
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