Abstracts

[italic]Status epilepticus[/italic] (SE) has been associated with brain damage and plasticity in acute and chronic phases of temporal lobe epilepsy in animal models. It has been shown that SE duration correlates with the severity of consequent tissue alterations. In this work, we intended to investigate if there is a correlation between behavior scores presented by animals during self-sustained SE (SSSE) and the number of brain injured areas found after 3 hours, 24 hours or 14 days. Adult, male Wistar rats, 240-320 g, were anesthetized with xilazine (0.7 mg/kg) and ketamine (1 mg/kg) and implanted with stainless steel coated electrodes in left amygdala (AMY) and hippocampus (HIP). EEG data was acquired from both AMY and HIP. A stainless steel screw attached to frontal skull was used as reference electrode. In order to induce SE, we applied to AMY 30 min of electrical stimulation (biphasic square waves, 100 ms duration, 300 [mu]A, 60 Hz, each half a second). We only included in this study animals that presented SSSE after stimulation (n = 22). Additional 11 animals were not stimulated (controls). All animals were rescued (diazepam, 5 mg/kg) after 2 hours of SE. Based on video-EEG files, we classified each 5 min of SE using a Seizure Severity Index (SSI) proposed by Pinel and Rovner (Exp Neurol, 1978, 58(2): 190-202). Animals were perfused under deep anesthesia (thionembutal, 60 mg/kg) 3 hours, 24 hours or 14 day after SE onset. Nissl-stained and Neu-N immunohistochemistry slices (40 [mu]m) were used to confirm electrodes tips position and integrity of tissue. Different types of SSSE were observed in stimulated animals: (i) SE-I (50 %), with facial automatisms, neck and forelimb myoclonus, rearing and falling and tonic-clonic generalized seizures and (ii) SE-II (50 %), with facial automatisms, neck myoclonus and concomitant exploratory behavior. Statistical analysis showed that SE-I is more severe than SE-II, when compared by SSI (p [lt] 0.05; ANOVA on Ranks, Tukey test), during the 1.5 hour of SSSE between the end of electrical stimulation and the rescue. Analysis of Nissl and Neu-N protein showed that there is a positive correlation between the type of SE and the quantity of injured areas both 24 hours (R = 0.873) and 14 days (R = 0.798) after SSSE (Pearson correlation, p [lt] 0.01). Qualitatively, there is evident neuronal loss in piriform cortex and HIP. Control animals did not present seizure behaviors or evident neuronal loss. Those results indicate that, in addition to the duration of SE, severity of seizure during SE influences the subjacent brain alterations consequent to it. Based on our data, we suggest that further analysis of brain alterations subjacent to SE should be observed considering the type of SE presented by the animals. (Supported by FAPESP, PRONEX, PROAP-Capes, CNPq and FAEPA.)