title: Layer-specific expression of Cl- transporters and differential [Cl-]i in newborn rat cortex.
abstract: GABA is the main inhibitory neurotransmitter in the adult brain. However, GABAergic transmission is depolarizing during early postnatal development, suggesting that changes in the expression of cation-Cl- co-transporters regulating neuronal Cl- homeostasis underlie the ontogeny of GABAergic functions. The developmental changes in the expressions of Cl- co-transporter mRNAs in the neocortex were in opposite directions for NKCC1 (Cl- uptake) and KCC2 (Cl- extrusion). In the newborn, NKCC1 mRNA expression was highest in ventricular zone followed by cortical plate, and then by Layer V/VI, while the reverse was true for KCC2 mRNA. The [Cl-]i levels were in the same rank order as for NKCC1 mRNA. Thus, the ontogeny of Cl- homeostasis in neocortical neurons could be regulated via the differential expression of NKCC1 and KCC2.
authors.affiliation: Department of Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan.
authors.forename: Chigusa
authors.initials: C
authors.lastname: Shimizu-Okabe
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yokokura
authors.forename: Akihito
authors.initials: A
authors.lastname: Okabe
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeda
authors.forename: Kohji
authors.initials: K
authors.lastname: Sato
authors.forename: Werner
authors.initials: W
authors.lastname: Kilb
authors.forename: Heiko J
authors.initials: HJ
authors.lastname: Luhmann
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics* / Q000378:metabolism*; D064506:Solute Carrier Family 12, Member 2; D027981:Symporters / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000502:physiology; D000096922:K Cl- Cotransporters
chemical_list: D002712:Chlorides; D012333:RNA, Messenger; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D027981:Symporters; D005680:gamma-Aminobutyric Acid; D000096922:K Cl- Cotransporters; C578879:Slc12a2 protein, rat