Chloride homeostasis differentially affects GABA(A) receptor- and glycine receptor-mediated effects on spontaneous circuit activity in hippocampal cell culture.
The potassium-chloride cotransporter 2 (KCC2)-dependent intracellular chloride level determines whether neurons respond to GABA and/or glycine by depolarization or hyperpolarization. However, still unknown is the role of KCC2-dependent chloride homeostasis in regulating the spontaneous activity of neuronal circuits via GABA(A) receptor (GABA(A)R) and the glycine receptor (GlyR). In this study, patch-clamp recordings were performed to measure the change of spontaneous neuronal activity in cultured hippocampal neurons. Our results showed that inhibition of KCC2 with furosemide, as well as blockade of GABA(A)R with bicuculline, significantly enhanced circuit activity. Perfusion with bicuculline further enhanced the effects of furosemide on spontaneous circuit activity, while furosemide did not alter the effects of bicuculline. Surprisingly, blockade of GlyR not only induced obvious tonic currents, but also significantly decreased spontaneous synaptic activity. Moreover, inhibition of KCC2 did not change the depressive effect of strychnine on neuronal circuits. Our findings suggest that KCC2-dependent chloride homeostasis is mainly involved in GABA(A)R-mediated synaptic inhibition whereas GlyR-mediated tonic action plays a totally different role in regulating hippocampal circuit activity.
Wang
Wei
W
Department of Neurobiology and Biophysics, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China.
Xu
Tian-Le
TL
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D005665:Furosemide / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism; D018684:Glycine Agents / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*; D018009:Receptors, Glycine / Q000187:drug effects / Q000378:metabolism*; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D013331:Strychnine / Q000494:pharmacology; D027981:Symporters / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism; D000096922:K Cl- Cotransporters
D001640:Bicuculline; D018118:Chloride Channels; D002712:Chlorides; D005665:Furosemide; D018756:GABA Antagonists; D005998:Glycine; D018684:Glycine Agents; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D049994:Sodium Potassium Chloride Symporter Inhibitors; D013331:Strychnine; D027981:Symporters; D005680:gamma-Aminobutyric Acid; D000096922:K Cl- Cotransporters