Developmental regulation of AMPA-receptor properties in CA1 pyramidal neurons of rat hippocampus

AMPA-receptor (AMPA-R) currents were recorded from CAI pyramidal neurons in situ and after acute isolation from the hippocampus of 3- to 45-day-old ra ts. Membrane currents were analyzed by combining the patch clamp method wit h fast application techniques. The complete block of receptor currents by G YKI 53655 and the absence of modulation by Concanavalin A indicated that th e cells exclusively expressed non-NMDA glutamate receptors of the AMPA subt ype while functional kainate receptors could not be detected. The lowest se nsitivity to kainate and NBQX was observed at postnatal day (p) Is. These c hanges might reflect a lower abundance of GluR1 at that developmental stage . A decrease of potentiation of receptor currents by cyclothiazide (CTZ), a n acceleration of the recovery from CTZ potentiation and a faster and more complete desensitization of glutamate-evoked currents suggest an up-regulat ion of flop splice variants with increasing age. These functional data indi cate that AMPA-R expression in CAI pyramidal neurons varies during postnata l development which can be expected to influence the kinetics of synaptic t ransmission and the excitotoxic vulnerability as well. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.