title: Serotoninergic modulation of GABAergic synaptic transmission in developing rat CA3 pyramidal neurons.
abstract: Serotoninergic modulation of GABAergic mIPSCs was investigated in immature (postnatal 12-16-days old) rat CA3 pyramidal neurons using a conventional whole-cell patch clamp technique. Serotonin or 5-hydroxytryptamine (5-HT) (10 micromol/L) transiently and explosively increased mIPSC frequency with a small increase in the current amplitude. However, 5-HT did not affect the GABA-induced postsynaptic currents, indicating that 5-HT acts presynaptically to facilitate the probability of spontaneous GABA release. The 5-HT action on GABAergic mIPSC frequency was completely blocked by 100 nmol/L MDL72222, a selective 5-HT(3) receptor antagonist, and mimicked by mCPBG, a selective 5-HT(3) receptor agonist. The 5-HT action on GABAergic mIPSC frequency was completely occluded either in the presence of 200 mumol/L Cd2+ or in the Na+-free external solution, suggesting that the 5-HT(3) receptor-mediated facilitation of mIPSC frequency requires a Ca2+ influx passing through voltage-dependent Ca2+ channels from the extracellular space, and that presynaptic 5-HT(3) receptors are less permeable to Ca2+. The 5-HT action on mIPSC frequency in the absence or presence of extracellular Na+ gradually increased with postnatal development. Such a developmental change in the 5-HT(3) receptor-mediated facilitation of GABAergic transmission would play important roles in the regulation of excitability as well as development in CA3 pyramidal neurons.
authors.affiliation: Department of Pharmacology, School of Dentistry, Kyungpook National University, Republic of Korea.
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Choi
authors.forename: Jin-Hwa
authors.initials: JH
authors.lastname: Cho
authors.forename: Jung-Tak
authors.initials: JT
authors.lastname: Kim
authors.forename: Eun-Joo
authors.initials: EJ
authors.lastname: Park
authors.forename: Maan-Gee
authors.initials: MG
authors.lastname: Lee
authors.forename: Hong-In
authors.initials: HI
authors.lastname: Shin
authors.forename: Byung-Ju
authors.initials: BJ
authors.lastname: Choi
authors.forename: Il-Sung
authors.initials: IS
authors.lastname: Jang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009924:Organ Culture Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D044406:Receptors, Serotonin, 5-HT3 / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D058827:Serotonin 5-HT3 Receptor Agonists; D058831:Serotonin 5-HT3 Receptor Antagonists; D013347:Subcellular Fractions; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D044406:Receptors, Serotonin, 5-HT3; D058827:Serotonin 5-HT3 Receptor Agonists; D058831:Serotonin 5-HT3 Receptor Antagonists; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D002118:Calcium