title: Differential functional expression of cation-Cl- cotransporter mRNAs (KCC1, KCC2, and NKCC1) in rat trigeminal nervous system.
abstract: GABA is the main inhibitory neurotransmitter in the adult brain, which causes Cl- influx into the cell via GABAA receptors. The direction of Cl- inflow is dependent on the Cl- gradient across the membrane. Cation-Cl- cotransporters have been considered to play pivotal roles in controlling intracellular Cl- concentration ([Cl-]i) of neurons; hence, they modulate the GABAergic function. To elucidate how these cotransporters are distributed in the trigeminal nuclei, we investigated the expressions of K+-Cl- cotransporters (KCC1 and KCC2) and Na+-K+-2Cl- cotransporter (NKCC1) mRNAs by using in situ hybridization histochemistry. KCC2 mRNA was expressed in the motor trigeminal nucleus (Mo5), the principal trigeminal nucleus (Pr5), and the spinal trigeminal nucleus (Sp5), but not in the trigeminal ganglion (TG) and the mesencephalic trigeminal nucleus (Me5). On the other hand, KCC1 and NKCC1 mRNAs were expressed in all the trigeminal nuclei. The resting [Cl-]i of Me5 neurons was significantly higher than that of Mo5 neurons. Thus, in primary sensory neurons such as the TG and the Me5, [Cl-]i would be higher than those in the other trigeminal nuclei because of the lack of KCC2 mRNA expression. Since Me5 neurons, but not Mo5 neurons, responded to GABA by depolarization, GABA would have differential physiological functions among trigeminal nuclei and TG.
authors.affiliation: Department of Physiology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Toyoda
authors.forename: Junko
authors.initials: J
authors.lastname: Yamada
authors.forename: Shinya
authors.initials: S
authors.lastname: Ueno
authors.forename: Akihito
authors.initials: A
authors.lastname: Okabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kato
authors.forename: Kohji
authors.initials: K
authors.lastname: Sato
authors.forename: Kenji
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology; D006096:Gramicidin; D017403:In Situ Hybridization / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; 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*; D014278:Trigeminal Nuclei / Q000166:cytology / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology; D000096922:K Cl- Cotransporters
chemical_list: D002712:Chlorides; D006096:Gramicidin; 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