title: Q- and L-type calcium channels control the development of calbindin phenotype in hippocampal pyramidal neurons in vitro.
abstract: Cultured immature hippocampal neurons from embryonic 17-day-old rats were used to explore activity-dependent regulation of neuronal phenotype differentiation in the developing hippocampus. The calbindin-D28k phenotype of the pyramidal neurons appeared during the first 6 days in culture, and was expressed by 12% of the cells on day 6. Daily stimulation with 50 mM KCl during the first 5 days in vitro increased the number of calbindin-D28k-positive pyramidal neurons without affecting neuronal survival. This effect was prevented by buffering extracellular Ca2+. Omega-agatoxin-IVA-sensitive Q-type and nitrendipine-sensitive L-type voltage-gated Ca2+ channels (VGCCs) carried Ca2+ currents and Ca2+ influx in immature pyramidal neurons at somata level. Blockade of these channels inhibited calbindin-D28k phenotype induced by 50 mM KCl. Conversely, glutamate-activated Ca2+ channel antagonists did not affect the KCl-induced calbindin-D28k phenotype. Chronic blockade of Q- and/or L-type VGCCs downregulated the normal calbindin-D28k development of immature pyramidal neurons without affecting neuronal survival, the somatic area of pyramidal neurons or the number of GABAergic-positive (gamma-aminobutyric acid) interneurons. However, at later developmental stages, Q-type VGCCs lost their ability to control Ca2+ influx at somata level, and both Q- and L-type VGCCs failed to regulate calbindin-D28k phenotype. These results suggest that Q-type channels, which have been predominantly associated with neurotransmitter release in adult brain, transiently act in synergy with L-type VGCCs to direct early neuronal differentiation of hippocampal pyramidal neurons before the establishment of their synaptic circuits.
authors.affiliation: Inserm U-432, Université Montpellier II, Place Eugène Bataillon, 34095, Montpellier, Cedex 5, France.
authors.forename: H
authors.initials: H
authors.lastname: Boukhaddaoui
authors.forename: V
authors.initials: V
authors.lastname: Sieso
authors.forename: F
authors.initials: F
authors.lastname: Scamps
authors.forename: S
authors.initials: S
authors.lastname: Vigues
authors.forename: A
authors.initials: A
authors.lastname: Roig
authors.forename: J
authors.initials: J
authors.lastname: Valmier
mesh_terms: D000818:Animals; D064092:Calbindin 1; D064026:Calbindins; D002118:Calcium / Q000493:pharmacokinetics; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020907:Calcium Channels, Q-Type / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D018698:Glutamic Acid / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology; D009568:Nitrendipine / Q000494:pharmacology; D010641:Phenotype; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D017966:Pyramidal Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000235:genetics*; D005680:gamma-Aminobutyric Acid / Q000235:genetics; D020867:omega-Agatoxin IVA / Q000494:pharmacology; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
chemical_list: C576500:Calb1 protein, rat; D064092:Calbindin 1; D064026:Calbindins; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D020907:Calcium Channels, Q-Type; D064030:S100 Calcium Binding Protein G; D020867:omega-Agatoxin IVA; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D011189:Potassium Chloride; D020866:omega-Conotoxin GVIA; D009568:Nitrendipine; D002118:Calcium