Regional differences in GABAergic modulation for TEA-induced synaptic plasticity in rat hippocampal CA1, CA3 and dentate gyrus.
Tetraethylammonium (TEA), a K(+)-channel blocker, reportedly induces long-term potentiation (LTP) of hippocampal CA1 synaptic responses, but at CA3 and the dentate gyrus (DG), the characteristics of TEA-induced plasticity and modulation by inhibitory interneurons remain unclear. This study recorded field EPSPs from CA1, CA3 and DG to examine the involvement of GABAergic modulation in TEA-induced synaptic plasticity for each region. In Schaffer collateral-CA1 synapses and associational fiber (AF)-CA3 synapses, bath application of TEA-induced LTP in the presence and absence of picrotoxin (PTX), a GABA(A) receptor blocker, whereas TEA-induced LTP at mossy fiber (MF)-CA3 synapses was detected only in the absence of GABA(A) receptor blockers. MF-CA3 LTP showed sensitivity to Ni(2+), but not to nifedipine. In DG, synaptic plasticity was modulated by GABAergic inputs, but characteristics differed between the afferent lateral perforant path (LPP) and medial perforant path (MPP). LPP-DG synapses showed TEA-induced LTP during PTX application, whereas at MPP-DG synapses, TEA-induced long-term depression (LTD) was seen in the absence of PTX. This series of results demonstrates that TEA-induced DG and CA3 plasticity displays afferent specificity and is exposed to GABAergic modulation in an opposite manner.
Department of Psychology, Graduate School of the Humanities, Senshu University, 2-1-1 Higashimita, Tama, Kawasaki, Kanagawa 214-8580, Japan.
Etsuko
E
Suzuki
Takashi
T
Okada
D000818:Animals; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology; D008297:Male; D019599:Mossy Fibers, Hippocampal / Q000187:drug effects / Q000378:metabolism; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009532:Nickel / Q000494:pharmacology; D009924:Organ Culture Techniques; D019580:Perforant Pathway / Q000187:drug effects / Q000378:metabolism; D010852:Picrotoxin / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D009532:Nickel; D010852:Picrotoxin; D026902:Potassium Channel Blockers; D011963:Receptors, GABA-A; D019789:Tetraethylammonium; D005680:gamma-Aminobutyric Acid