title: Differential expression of KCC2 accounts for the differential GABA responses between relay and intrinsic neurons in the early postnatal rat olfactory bulb.
abstract: The rat olfactory bulb is anatomically immature at birth, and considerable neurogenesis and synaptogenesis are known to take place postnatally. In addition, significant physiological changes have also been reported in this period. For example, granule cell-mediated inhibition following electrical stimulations to the lateral olfactory tract is robust during the first postnatal week, and then decreases abruptly after the second week. However, the mechanism underlying this enhanced inhibition remains to be elucidated. To know the cause of this phenomenon, we investigated the expression patterns of cation-Cl(-) co-transporters (KCC1, KCC2 and NKCC1) mRNAs, which are responsible for the regulation of [Cl(-)](i). In addition, responses to gamma-aminobutyric acid (GABA) were measured by gramicidin-perforated patch-clamp recordings and Ca(2+) imaging using fura-2. We found that in the early postnatal period, mitral cells expressing KCC2 mRNA were inhibited by GABA, while granule cells lacking KCC2 mRNA expression were depolarized or excited by GABA. These results indicate that transient GABA-mediated excitation on granule cells might be the main cause of the enhanced inhibition on mitral cells, and suggest that these differential GABA responses between relay and intrinsic neurons play pivotal roles in the early postnatal rat olfactory bulb.
authors.affiliation: Department of Anatomy & Neuroscience, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan.
authors.forename: Cong
authors.initials: C
authors.lastname: Wang
authors.forename: Koji
authors.initials: K
authors.lastname: Ohno
authors.forename: Tomonori
authors.initials: T
authors.lastname: Furukawa
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Ueki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeda
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fukuda
authors.forename: Kohji
authors.initials: K
authors.lastname: Sato
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D003952:Diagnostic Imaging / Q000379:methods; D004558:Electric Stimulation / Q000379:methods; D016257:Fura-2 / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects* / Q000502:physiology; D006096:Gramicidin / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009830:Olfactory Bulb / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D064506:Solute Carrier Family 12, Member 2; D027981:Symporters / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*; D000096922:K Cl- Cotransporters
chemical_list: D002118:Calcium; D016257:Fura-2; D006096:Gramicidin; 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