Neuronal Transmembrane Chloride Transport Has a Time-Dependent Influence on Survival of Hippocampal Cultures to Oxygen-Glucose Deprivation

Abstract

Neuronal ischemia results in chloride gradient alterations which impact the excitatory–inhibitory balance, volume regulation, and neuronal survival. Thus, the Na+/K+/Cl− co-transporter (NKCC1), the K+/ Cl− co-transporter (KCC2), and the gamma-aminobutyric acid A (GABAA) receptor may represent therapeutic targets in stroke, but a time-dependent effect on neuronal viability could influence the outcome. We, therefore, successively blocked NKCC1, KCC2, and GABAA (with bumetanide, DIOA, and gabazine, respectively) or activated GABAA (with isoguvacine) either during or after oxygen-glucose deprivation (OGD). Primary hippocampal cultures were exposed to a 2-h OGD or sham normoxia treatment, and viability was determined using the resazurin assay. Neuronal viability was significantly reduced after OGD, and was further decreased by DIOA treatment applied during OGD (p < 0.01) and by gabazine applied after OGD (p < 0.05). Bumetanide treatment during OGD increased viability (p < 0.05), while isoguvacine applied either during or after OGD did not influence viability. Our data suggests that NKCC1 and KCC2 function has an important impact on neuronal viability during the acute ischemic episode, while the GABAA receptor plays a role during the subsequent recovery period. These findings suggest that pharmacological modulation of transmembrane chloride transport could be a promising approach during stroke and highlight the importance of the timing of treatment application in relation to ischemia-reoxygenation.

Protective Role of Low Ethanol Administration Following Ischemic Stroke via Recovery of KCC2 and p75NTR Expression

“…This present work confirms that KCC2 protein levels in the plasma membrane of neurons are substantially reduced in the acute, focal ischemic mice model, as observed previously in other stroke models [18][19][20][21]. We subsequently accomplished a rescue of the KCC2 levels and GABA-mediated responses in neurons of the peri-infarct zone by supplementation of the drinking water with 3% ethanol for 5 days post-ischemia.…”

Targeting the WNK-SPAK/OSR1 Pathway and Cation-Chloride Cotransporters for the Therapy of Stroke

“…In addition, bumetanide (10 µM) was used in another study to block NKCC1 in order to facilitate decreased [Cl − ] i in hippocampal tissue cultured from rats either during oxygen-glucose deprivation for 120 min or post-exposure. The drug improved neuronal viability during the acute ischemic episode which suggested its critical role in the modulation of transmembrane chloride transport [ 27 ].…”

“…Ischemia is the disruption of blood flow and the subsequent depletion of oxygen and glucose. As neuronal components strictly function on aerobic metabolism [ 23 ], an ischemia in the brain leads to reduced available ATP levels and ionic imbalance across the neuronal cell membrane [ 24 ], which causes irreversible neuronal death, also known as ischemic stroke [ 25 , 26 , 27 ]. During this process, an imbalance of excitatory glutamate and inhibitory gamma amino acid butyric acid (GABA) further accelerate neuronal demise [ 28 , 29 , 30 ], subsequently leading to the onset of post-stroke seizures [ 20 , 31 , 32 ].…”

“…The switch from excitatory to inhibitory during neurodevelopment, a process termed excitatory-to-inhibitory GABA switch, is generated through reduction in NKCC1 level and increase in KCC2 level [ 34 ]. The expanding work on CCC influence on neuronal excitability in physiological conditions especially during development and pathological conditions suggest that they could be a new treatment approach for stroke [ 27 ].…”

Symmetric and Asymmetric Synapses Driving Neurodegenerative Disorders

“…Immediately after an ischemic event, large amounts of glutamate contribute to a strong activation of NMDARs that downregulates the expression of both GABA A and GABA B receptors through a phosphorylation process activated by high levels of Ca 2+ (Figure 1) [32,[43][44][45][46]. Accordingly, phasic GABA signaling is reduced in the first weeks after stroke [28,40].…”