GABAergic Signaling at Mossy Fiber Synapses in Neonatal Rat Hippocampus

Autor: Fiorenzo Conti, Giorgia Fattorini, Victoria F. Safiulina, Enrico Cherubini
Rok vydání: 2006
Předmět:
Patch-Clamp Techniques
Nipecotic Acids
Action Potentials
Synaptic Transmission
Propanolamines
immature hippocampus
Oximes
pyramidal cells and interneurons
VGAT
Excitatory Amino Acid Agonists
Picrotoxin
Cation Transport Proteins
gamma-Aminobutyric Acid
Aminobutyrates
Pyramidal Cells
General Neuroscience
Glutamate receptor
mossy fiber synapses
GABA release
spontaneous synaptic events
VGLUT1
medicine.anatomical_structure
Mossy Fibers
Hippocampal
GABAergic
GABA Uptake Inhibitors
medicine.drug
Development/Plasticity/Repair
Glutamic Acid
Biology
Bicuculline
Inhibitory postsynaptic potential
gamma-Aminobutyric acid
Flurazepam
Interneurons
Quinoxalines
Reaction Time
medicine
Animals
GABA transporter
Receptors
AMPA
Rats
Wistar
Receptors
GABA-A
Granule cell
Phosphinic Acids
Electric Stimulation
Rats
Animals
Newborn
nervous system
Metabotropic glutamate receptor
Dentate Gyrus
Vesicular Glutamate Transport Protein 1
biology.protein
Neuroscience
Zdroj: The Journal of Neuroscience. 26:597-608
ISSN: 1529-2401
0270-6474
Popis: In the adult rat hippocampus, granule cell mossy fibers (MFs) form excitatory glutamatergic synapses with CA3 principal cells and local inhibitory interneurons. However, evidence has been provided that, in young animals and after seizures, the same fibers can release in addition to glutamate GABA. Here we show that, during the first postnatal week, stimulation of granule cells in the dentate gyrus gave rise to monosynaptic GABAA-mediated responses in principal cells and in interneurons. These synapses were indeed made by MFs because they exhibited strong paired-pulse facilitation, high sensitivity to the metabotropic glutamate receptor agonistl-AP-4, and short-term frequency-dependent facilitation. MF responses were potentiated by blocking the plasma membrane GABA transporter GAT-1 with NO-711 or by allosterically modulating GABAAreceptors with flurazepam. Chemical stimulation of granule cell dendrites with glutamate induced barrages of GABAA-mediated postsynaptic currents into target neurons. Furthermore, immunocytochemical experiments demonstrated colocalization of vesicular GABA transporter with vesicular glutamate transporter-1 and zinc transporter 3, suggesting that GABA can be taken up and stored in synaptic vesicles of MF terminals.Additional fibers releasing both glutamate and GABA into principal cells and interneurons were recruited by increasing the strength of stimulation. Both the GABAergic and the glutamatergic component of synaptic currents occurred with the same latency and were reversibly abolished byl-AP-4, indicating that they originated from the MFs. GABAergic signaling may play a crucial role in tuning hippocampal network during postnatal development. Low-threshold GABA-releasing fibers may undergo elimination, and this may occur when GABA shifts from the depolarizing to the hyperpolarizing direction.
Databáze: OpenAIRE
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