Experience-dependent changes in intracellular Cl- regulation in developing auditory neurons.
A developmental change in GABA and glycine responses, from a depolarization to a hyperpolarization, have been reported for a range of CNS neurons, and has been demonstrated to be due to a developmental decrease in the intracellular Cl- concentration ([Cl-](i)). We examined [Cl-](i) in isolated rat lateral superior olive (LSO) neurons using patch-clamp recordings of glycine gated Cl- currents and by measuring intracellular Cl- -fluorescence. In neurons from 14-16-day-old rats (P14-P16), which had previously received unilateral or bilateral cochlear ablations before the onset of hearing, there was no developmental decrease in [Cl-](i). No significant differences in [Cl-](i) were observed amongst rats with either ipsi- and contralateral ablations. Implanted strychnine pellets also prevented the decrease in [Cl-](i) in most neurons. In some of these neurons in which [Cl-](i) remained high, there was a lack of expression of the K+-Cl- cotransporter 2 (KCC2) mRNA. These results demonstrate that the developmental decrease in [Cl-](i) in LSO neurons is dependent on neuronal activity and that both GABAergic/glycinergic and glutamatergic afferent activity contribute to this maturation of the Cl- regulatory mechanisms.
Shibata
Shumei
S
Department of Cellular and System Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
Kakazu
Yasuhiro
Y
Okabe
Akihito
A
Fukuda
Atsuo
A
Nabekura
Junichi
J
D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D000831:Animals, Newborn; D002712:Chlorides / Q000378:metabolism*; D003051:Cochlea / Q000254:growth & development / Q000378:metabolism; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D007424:Intracellular Fluid / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009847:Olivary Nucleus / Q000254:growth & development / Q000378:metabolism*; D051381:Rats
D002712:Chlorides