Abstracts

RATIONALE: Seizures alter the rate of dentate granule neuron (DGN) neurogenesis. After status epilepticus (SE) there is a dramatic increase in the rate of DGN neurogenesis. It is not known what the consequences of increased DGN neurogenesis are for the development of epilepsy and if these newborn DGN persist. Prior studies have described a 20 fold increase in the rate of DGN neurogenesis 7 days after a bout of pilocarpine induced SE in 3 week old rats. Here we study the survival of these newborn DGN over time. At the end of this activity the participant should be able to discuss the survival of DGN born after SE.
METHODS: We have induced status epilepticus in postnatal day 20 rats with an injection of lithium-pilocarpine, and labeled DGNs undergoing cell division with bromo-deoxyuridine (BrdU) a thimidine analog 4, 6,and 8 days after SE. The animals were then sacrificed one week later on P34 and the number of BrdU labeled cells within the dentate was quantified per square micron of dentate.
RESULTS: There was a 2.6 fold increase in the number of BrdU labeled DGNs in the SE treated animals as compared to control littermates. (Li-Pilo-2.25X10^-4Brdu neurons/micron², (SE[plusminus]5X10^-5); Li-Saline-0.87X10-4,(SE[plusminus]3.3X10^-5); Naive-1.1X10-4,(SE[plusminus]3.5X10-5).
CONCLUSIONS: In P20 rats one week after Li-Pilocarpine induced SE the rate of DGN neurogenesis has been reported to increase 20 fold (Sankar et al. Epilepsia, 2000 V41, S6, p53-6). When followed over time the number of DGN born 1 week after SE decrease to only a 2.6 fold increase over controls. The current study suggests that the majority of the DGN born one week after SE do not persist. Studies are underway to understand the mechanism by which newly born DGN are lost after SE.
[Supported by: ABK- Child Neurology Foundation, NINDS-RO1-NS38595.
BEP-Dana Brown Epilepsy Fellowship,Epifellows, NINDS-NS 07413]