Dissociation between mossy fiber sprouting and rapid kindling with low-frequency stimulation of the amygdala
Date
1997
Authors
Armitage, Lisa Lorraine
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Abstract
To determine whether sprouting of hippocarnpal mossy fibers is invariably correlated with kindling of seizures, rats were subjected to rapid kindling with long trains of low-frequency stimulation of the arnygdala, which resulted in development of generalized seizures within a mean of 5 stimulations. For comparison other rats were subjected to conventional kindling with short trains of high-frequency stimulation of the arnygdala, which resulted in development of generalized seizures within a mean of about 13 stimulations. The purpose of using the rapid kindling technique was so that we could attempt to tease apart the time course of mossy fiber sprouting and kindling. There was no evidence of mossy fiber sprouting in the brains of rats killed 1 day after completion of rapid kindling, as compared to yoked controls, although significant sprouting was seen in rats killed I day after completion of conventional kindling. Examination of tissue from rats killed 20 days after rapid kindling, however, revealed significant sprouting, suggesting that mossy fiber sprouting can be triggered by rapid kindling if sufficient elapsed time is allowed. The observed disparity between completion of rapid low-frequency kindling and detection of mossy fiber sprouting suggests that mossy fiber sprouting may be associated more with an elapse of time after neuronal activation than with kindling per se. Furthermore, the similar time course of conventional kindling and of mossy fiber sprouting precludes a causal role of mossy fiber sprouting in conventional kindling.