Activation of interneurons at the stratum oriens/alveus border suppresses excitatory transmission to apical dendrites in the CA1 area of the mouse hippocampus.
The consequences of activation or inactivation of interneurons at the CA1 stratum oriens/ alveus border for signal transmission at the apical dendritic region of pyramidal cells were investigated in slices from mice submerged in a perfusion chamber. A characteristic subpopulation of interneurons with a horizontal dendritic tree in this region, which sends a GABAergic projection to the apical dendrites of CA1 pyramidal cells is strongly excited by metabotropic glutamate receptor activation and receives GABAergic input from vasoactive intestinal polypeptide-containing interneurons. Pressure ejection of glutamate or the metabotropic agonist 1s,3r-aminocyclopentane dicarboxylic acid from micropipettes onto the stratum oriens/alveus border caused a long lasting (more than 90 min) decrease of field-excitatory postsynaptic potentials in the strata radiatum and lacunosum-moleculare. The GABAB antagonist CGP 35348 (100 microM in the perfusion fluid) partially and reversibly blocked this effect. Vasoactive intestinal polypeptide- (0.1 microM in the bath) excited neurons with response and firing properties characteristic for interneurons at the oriens/alveus border. Local pressure application of vasoactive intestinal polypeptide (10 microM) to the alveus region led, after a brief (2 min) and small (10%) increase, to a longer lasting (30-50 min) decrease (by 20-30%) in the slope of the field-excitatory postsynaptic potential in strata radiatum and lacunosum-moleculare. This action was completely blocked by bath application of CGP 35348. Local application of tetrodotoxin in the stratum oriens/alveus region markedly increased the slope of evoked dendritic excitatory postsynaptic potentials, and caused multiple firing of pyramidal cells. Thus, stratum oriens/alveus interneurons have a profound inhibitory effect on signal transmission in the apical dendritic area of CA1, which is, at least in part, mediated by GABAB receptors. It appears that the GABAB receptor-mediated effect in stratum lacunosum-moleculare is produced by vasoactive intestinal polypeptide-sensitive interneurons.
Yanovsky
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Y
Institute of Physiology II, Heinrich-Heine-Univerisity, Düsseldorf, Germany.
Sergeeva
O A
OA
Freund
T F
TF
Haas
H L
HL
D000818:Animals; D003712:Dendrites / Q000737:chemistry / Q000502:physiology*; D004594:Electrophysiology; D018698:Glutamic Acid / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D007395:Interneurons / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D017966:Pyramidal Cells / Q000737:chemistry / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology; D018080:Receptors, GABA-B / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D018094:Receptors, Metabotropic Glutamate; D014660:Vasoactive Intestinal Peptide; D018698:Glutamic Acid; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid