title: Role of low-voltage-activated calcium current and extracellular calcium in controlling the firing pattern of developing CA1 pyramidal neurons.
abstract: The firing pattern of individual neurons is an important element for information processing and storing. During the first weeks of development, there is a transitional period during which CA1 pyramidal neurons display burst-spiking behavior in contrast to the adult regular-firing pattern. Spike after-depolarizations (ADPs) constitute a major factor underlying burst-spiking behavior. Using current-clamp recordings, we studied ADP waveforms and firing patterns in CA1 pyramidal neurons of Wistar rats from 9 to 19 postnatal days (P9-19). The percentage of burst-spiking neurons increased up to P16, in correlation with the emergence of an active component in the ADP. The application of low-voltage-activated (LVA) calcium channel blockers such as nickel or mibefradil suppressed the generation of the active ADP component and burst-spiking behavior. In agreement with the development of the ADP waveform and burst-spiking behavior, voltage-clamp experiments in dissociated pyramidal neurons showed an increase in the LVA calcium current in P16-19 vs P9-12. Finally, we found that a reduction of extracellular calcium levels decreases the percentage of burst-spiking cells due to a reduction in the active component of the ADP. We conclude that a major contribution of LVA calcium channels to ADP determines the bursting capability of CA1 pyramidal neurons during a transitional postnatal period in contrast to adulthood.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain. Electronic address: alberto.sanchez_aguilera_lopez@kcl.ac.uk.
authors.forename: Alberto
authors.initials: A
authors.lastname: Sánchez-Aguilera
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Sánchez-Alonso
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: María Ángeles
authors.initials: MÁ
authors.lastname: Vicente-Torres
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Asunción
authors.initials: A
authors.lastname: Colino
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D020748:Mibefradil / Q000494:pharmacology; D009532:Nickel / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D017208:Rats, Wistar; D046509:Tissue Culture Techniques
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020748:Mibefradil; D009532:Nickel; D002118:Calcium
keywords: Burst-spiking firing pattern; CA1 pyramidal neurons; Development; Low-voltage-activated calcium current; Spike after-depolarization