Acute ClC-2 blockade increases neuronal intracellular chloride and depolarizes EGABA

Neuronal intracellular chloride levels influence the polarity and effectiveness of GABA receptors in inhibiting neurons. ClC-2 is a channel that allows chloride to leave cells, but how it directly impacts EGABA and overall chloride balance in neurons is not fully understood. Researchers used a drug called AK-42, which specifically blocks ClC-2, to investigate its effects on GABAergic chloride signaling in brain tissue slices.

They combined a technique called optogenetics to stimulate specific inhibitory nerve cells with a light-sensitive protein, measured the electrical signals produced in response, and measured chloride levels inside cells. AK-42 caused the electrical signals to become less negative (depolarized) compared to normal conditions, with this effect being more pronounced if the stimulation began 2 seconds after the cell's voltage was changed.

This suggests that ClC-2 activity becomes more active over time when the cell's voltage is steady. AK-42 also stopped the more negatively charged electrical signals that typically occur after a 2-second stimulation delay, and it changed the baseline electrical activity without significantly altering the cell's resting state. Measurements taken with a special imaging technique showed that AK-42 caused an increase in chloride inside neurons even when another substance that blocks all chloride channels was present.

Overall, these results demonstrate that blocking ClC-2 makes GABA signaling less negative, increases the amount of chloride inside neurons, and changes the timing of GABA's influence on neuron signaling, suggesting that ClC-2 plays an important role in quickly adjusting the chloride balance in nerve cells.