Loss of Inhibitory Neurons in the Brain’s Output Area and Its Role in Temporal Lobe Epilepsy

The density of GABAergic interneurons in the subiculum of pilocarpine-treated animals was significantly reduced.

• A substantial loss of parvalbumin-immunoreactive neurons was observed in the pyramidal cell and molecular layers.
• Calretinin-immunoreactive cells were predominantly reduced in the molecular layer.
• Despite an increased intensity of GAD65 immunoreactivity, the density of GAD65-containing synaptic terminals in the pyramidal cell layer was decreased.
• There was a decrease in evoked inhibitory post-synaptic currents, indicating impaired dendritic inhibition.
• The frequency of miniature inhibitory post-synaptic currents decreased by 30%, aligning with a 28% reduction in perisomatic GAD-positive terminals.
• These findings suggest that the vulnerability of subicular GABAergic interneurons may lead to a disturbance in the subicular inhibitory system.

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