Hyperpolarizing responses to application of glutamate in hippocampal CA1 pyramidal neurons.
Micropressure injection of glutamate onto the apical dendrites of hippocampal CA1 pyramidal cells usually produces a fast rising, brief depolarization. However, hyperpolarizing responses with longer durations (300-500 ms) can be produced over a range of drug electrode locations. These hyperpolarizations can be reversed with intracellular injection of hyperpolarizing current. Localized application of glutamate in the stratum radiatum produces a depolarizing response in intracellularly recorded CA1 interneurons. Previous studies have shown that the dendrites of GABA-ergic basket cell interneurons extend into the stratum radiatum and are involved in mediating feedforward inhibition of pyramidal neurons. The glutamate-induced hyperpolarizations observed in pyramidal neurons are probably due to direct excitation of dendrites of interneurons, which in turn produce a synaptic inhibition in pyramidal cells.
D000818:Animals; D004553:Electric Conductivity; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009433:Neural Inhibition; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005971:Glutamates; D018698:Glutamic Acid; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid