title: Group I mGluR agonist-evoked long-term potentiation in hippocampal oriens interneurons.
abstract: Several subtypes of interneurons in the feedback circuit in stratum oriens of the hippocampus exhibit NMDA receptor-independent long-term potentiation (LTP) at glutamatergic synapses made by local pyramidal neurons. LTP has been reported with both "Hebbian" and "anti-Hebbian" induction protocols, where high-frequency presynaptic stimulation is paired with either postsynaptic depolarization or hyperpolarization. Do these phenomena represent distinct forms of plasticity, dependent on group I metabotropic receptors (mGluRs) and rectifying Ca2+ -permeable AMPA receptors, respectively? Blockade of either mGluR1 or mGluR5 prevented anti-Hebbian LTP induction in stratum oriens interneurons in rat hippocampal slices. Exogenous activation of group I mGluRs by the selective agonist (S)-3,5-dihydroxyphenylglycine (DHPG) was unable to induce LTP on its own, and instead depressed excitatory transmission. However, when paired with postsynaptic hyperpolarization, DHPG or the group I metabotropic receptor (mGluR5)-selective agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG) elicited a delayed long-lasting potentiation, which was accompanied by a decrease in paired-pulse facilitation. Anti-Hebbian LTP occluded the effect of DHPG paired with hyperpolarization, implying that the induction cascades triggered by both conjunctions of stimuli converge on common expression mechanisms.
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Le Duigou
authors.forename: Dimitri M
authors.initials: DM
authors.lastname: Kullmann
mesh_terms: D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D055724:Electrophysiological Phenomena; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D007395:Interneurons / Q000187:drug effects*; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D010648:Phenylacetates / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists*; D012118:Resorcinols / Q000494:pharmacology
chemical_list: C107349:2-chloro-5-hydroxyphenylglycine; D001565:Benzoates; D018690:Excitatory Amino Acid Agonists; D010648:Phenylacetates; D011725:Pyridines; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; D012118:Resorcinols; C104077:metabotropic glutamate receptor type 1; C079694:alpha-methyl-4-carboxyphenylglycine; C079215:3,5-dihydroxyphenylglycine; C121465:6-methyl-2-(phenylethynyl)pyridine; D005998:Glycine