Long-term potentiation trains induce mossy fiber sprouting.

It has been shown that both amygdaloid and hippocampal kindling induce sprouting of the mossy fibers in the dentate gyrus. In this study, we investigated whether non-epileptogenic stimulation could also induce mossy fiber sprouting. Long-term potentiation (LTP) was induced in the dentate gyrus by the application of brief, high frequency trains to the perforant path. The potentiating stimulation was applied each day for 10 days, and the tissue was prepared for Timm labelling 7 days later. Sprouting was significantly increased in the LTP group compared to the implanted control rats. These results suggest that mossy fiber sprouting is not damage-induced and is dependent on neuronal activation.