Evidence for metabotropic glutamate receptor activation in the induction of depolarization-induced suppression of inhibition in hippocampal CA1.
Depolarization-induced suppression of inhibition (DSI) is a transient reduction of GABAA receptor-mediated IPSCs that is mediated by a retrograde signal from principal cells to interneurons. Using whole-cell recordings, we tested the hypothesis that mGluRs are involved in the DSI process in hippocampal CA1, as has been proposed for cerebellar DSI. Group II mGluR agonists failed to affect either evoked monosynaptic IPSCs or DSI, and forskolin, which blocks cerebellar DSI, did not affect CA1 DSI. Group I and group III mGluR agonists reduced IPSCs, but only group I agonists occluded DSI. (S)-MCPG blocked (1S,3R)-ACPD-induced IPSC suppression and markedly reduced DSI, whereas group III antagonists had no effect on DSI. Many other similarities between DSI and the (1S,3R)-ACPD-induced suppression of IPSCs also were found. Our data suggest that a glutamate-like substance released from pyramidal cells could mediate CA1 DSI by reducing GABA release from interneurons via the activation of group I mGluRs.
Morishita
W
W
Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Kirov
S A
SA
Alger
B E
BE
D015761:4-Aminopyridine / Q000494:pharmacology; D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D003521:Cyclopropanes / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D016318:Quisqualic Acid / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000737:chemistry / Q000502:physiology
D000600:Amino Acids, Dicarboxylic; D001565:Benzoates; D015220:Calcium Channels; D003521:Cyclopropanes; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018696:Neuroprotective Agents; D011963:Receptors, GABA-A; D018094:Receptors, Metabotropic Glutamate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; C079694:alpha-methyl-4-carboxyphenylglycine; C082313:2-(2,3-dicarboxycyclopropyl)glycine; C035261:(alpha-carboxycyclopropyl)glycine; D016318:Quisqualic Acid; D015761:4-Aminopyridine; D005033:Ethylmaleimide; D005998:Glycine