Abstracts

Rationale: Temporal lobe epilepsy (TLE) is one of the most common types of epilepsy. Kainic acid (KA) and Pilocarpine (PILO) administration in rats has frequently been used as animal models of TLE. Characterization of the neuropathological findings in both models of TLE has long been established and in our laboratory (Castro et al, Brain Res. 2011) have detected Fluoro-Jade (FJ) positive neurodegeneration patterns in the systemic PILO model. Currently we characterized the differences in neurodegeneration patterns when comparing systemic KA and PILO models of TLE using the silver impregnation (SI) and FJ techniques.Methods: Status epilepticus (SE) was induced in Wistar male rats by KA (9 mg/kg, IP) or PILO (320 mg/kg, IP) injection. Thirty minutes before PILO injection animals were treated with methyl-scopolamine (1 mg/kg, IP) to minimize PILO peripheral effects. Ninety minutes after both types of SE onset all animals were treated with diazepam (10 mg/kg, IP) and 24 hours after the end of SE all animals were deeply anesthetized, perfused and the brains sectioned in a cryostat. Neurodegeneration patterns were detected by two blinded observers, using the SI technique (KA and PILO), or FJ staining (only PILO) with the aid of an Olympus BX60 microscope. All procedures were approved by the Institution s Ethics Commission (# 028/2010).Results: All animals injected with PILO or KA had SE and no difference in their latency to SE (8.3 1.3: PILO; 12.0 2.6: KA, minutes). PILO-treated animals showed a discretely different pattern of neurodegeneration (100% vs 85%) by SI and FJ techniques, respectively. However, using the SI technique we found that 100% of the analyzed brain nuclei presented neurodegeneration after PILO-induced seizures, in contrast with 71% found in the same regions after KA-induced seizures (see Table 1). Selective laminar neurodegeneration patterns were more evident in CA1 of PILO-treated animals than in KA, using both techniques. These data strongly suggest that there is a clear difference in the detection of neurodegeneration patterns, with the use of SI and FJ techniques, when we compare the two chemoconvulsants (PILO and KA). Conclusions: We conclude that using the SI and FJ techniques we can detect selective neurodegeneration patterns in the PILO and KA models of TLE. Given this differential labeling, we highly recomend to use both techniques, alone or in co-localization protocols, to produce temporal and spacial neurodegeneration maps. Financial Support: FAPESP, FAPESP-Cinapce, PROEX-CAPES (Physiology, Neurology), CNPq, FAEPA.