title: Group II metabotropic glutamate receptors depress synaptic transmission onto subicular burst firing neurons.
abstract: The subiculum (SUB) is a pivotal structure positioned between the hippocampus proper and various cortical and subcortical areas. Despite the growing body of anatomical and intrinsic electrophysiological data of subicular neurons, modulation of synaptic transmission in the SUB is not well understood. In the present study we investigated the role of group II metabotropic glutamate receptors (mGluRs), which have been shown to be involved in the regulation of synaptic transmission by suppressing presynaptic cAMP activity. Using field potential and patch-clamp whole cell recordings we demonstrate that glutamatergic transmission at CA1-SUB synapses is depressed by group II mGluRs in a cell-type specific manner. Application of the group II mGluR agonist (2S,1'R,2'R,3'R)-2-(2, 3-dicarboxycyclopropyl)glycine (DCG-IV) led to a significantly higher reduction of excitatory postsynaptic currents in subicular bursting cells than in regular firing cells. We further used low-frequency stimulation protocols and brief high-frequency bursts to test whether synaptically released glutamate is capable of activating presynaptic mGluRs. However, neither frequency facilitation is enhanced in the presence of the group II mGluR antagonist LY341495, nor is a test stimulus given after a high-frequency burst. In summary, we present pharmacological evidence for presynaptic group II mGluRs targeting subicular bursting cells, but both low- and high-frequency stimulation protocols failed to activate presynaptically located mGluRs.
authors.affiliation: Neuroscience Research Center of the Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Kintscher
authors.forename: Jörg
authors.initials: J
authors.lastname: Breustedt
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Miceli
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schmitz
authors.forename: Christian
authors.initials: C
authors.lastname: Wozny
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D056654:CA3 Region, Hippocampal / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D003521:Cyclopropanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000600:Amino Acids, Dicarboxylic; D003521:Cyclopropanes; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; C114624:LY 341495; D018094:Receptors, Metabotropic Glutamate; D014966:Xanthenes; C108822:metabotropic glutamate receptor 2; C102718:metabotropic glutamate receptor 3; C082313:2-(2,3-dicarboxycyclopropyl)glycine; C035261:(alpha-carboxycyclopropyl)glycine; D018698:Glutamic Acid; D005998:Glycine