Decrease of GABA-immunoreactive neurons in the amygdala after electrical kindling in the rat

The present study was designed to investigate the effects of electrical kindling in vivo on GABA immunoreactivity (GABA-IR) of the lateral and basolateral amygdaloid nuclei 2-6 months post-stimulation. Male Sprague-Dawley rats were implanted with bipolar electrodes in the basolateral nucleus and stimulated once per day until 3-5 stage 5 seizures were observed. Coronal sections containing the amygdala were processed for GABA-IR using the contralateral side of the brain. Results indicate that, in comparison to controls, fully kindled animals showed a significant decrease in total number of GABA-IR amygdala neurons. Decreases in GABA-positive punctate structures surrounding unlabeled pyramidal cells were also observed, but not quantified. The present data suggest that epileptogenesis of the amygdala is associated with a significant reduction of GABA-IR in the lateral and basolateral areas throughout the contralateral amygdaloid nucleus.