Two populations of layer v pyramidal cells of the mouse neocortex: development and sensitivity to anesthetics.
Previous studies have shown that layer V pyramidal neurons projecting either to subcortical structures or the contralateral cortex undergo different morphological and electrophysiological patterns of development during the first three postnatal weeks. To isolate the determinants of this differential maturation, we analyzed the gene expression and intrinsic membrane properties of layer V pyramidal neurons projecting either to the superior colliculus (SC cells) or the contralateral cortex (CC cells) by combining whole cell recordings and single-cell RT-PCR in acute slices prepared from postnatal day (P) 5-7 or P21-30 old mice. Among the 24 genes tested, the calcium channel subunits alpha1B and alpha1C, the protease Nexin 1, and the calcium-binding protein calbindin were differentially expressed in adult SC and CC cells and the potassium channel subunit Kv4.3 was expressed preferentially in CC cells at both stages of development. Intrinsic membrane properties, including input resistance, amplitude of the hyperpolarization-activated current, and action potential threshold, differed quantitatively between the two populations as early as from the first postnatal week and persisted throughout adulthood. However, the two cell types had similar regular action potential firing behaviors at all developmental stages. Surprisingly, when we increased the duration of anesthesia with ketamine-xylazine or pentobarbital before decapitation, a proportion of mature SC cells, but not CC cells, fired bursts of action potentials. Together these results indicate that the two populations of layer V pyramidal neurons already start to differ during the first postnatal week and exhibit different firing capabilities after anesthesia.
Christophe
Elodie
E
Neurophysiology and New Microscopies Laboratory, INSERM U603, CNRS FRE 2500, Université Paris Descartes, 45 Rue des StPères, 75006 Paris, France.
Doerflinger
Nathalie
N
Lavery
Daniel J
DJ
Molnár
Zoltán
Z
Charpak
Serge
S
Audinat
Etienne
E
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000777:Anesthetics / Q000008:administration & dosage*; D000818:Animals; D000831:Animals, Newborn; D004305:Dose-Response Relationship, Drug; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D019579:Neocortex / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*
D000777:Anesthetics; D009419:Nerve Tissue Proteins