Abstracts

Pilocarpine induced status epilepticus (SE) in adult and immature animals results in neurodegenerative changes in many limbic, neocortical and thalamic structures. There are no data on possible damage in striatopallidal complex which represents a prominent inhibitory brain machinery supressing unwanted motor activities and selecting optimal motor programs. The present study was focused on distribution and dynamics of neuronal degeneration in the dorsal striatum and dorsal pallidum in immature rats surviving up to one week after lithium-pilocarpine SE. Experiments were performed in Wistar rat pups 12, 15, 18, 21 and 25 days old housed under controlled enviroment (12/12 h light/dark cycle, 50-60% humidity) with free access to food and water. Lithium-pilocarpine model of SE was used. LiCl (3 mmol/kg, i.p.) was injected 24 hours before pilocarpine (40 mg/kg, i.p). Only animals exhibiting convulsive SE were included in this study. Rats of all age groups were sacrificed at 4, 8, 12, 24, 48 hours and 1 week after SE. Four to five animals were processed in each survival interval. Animals were deeply anesthetized with urethane (2.5 g/kg, i.p.) and perfused with 0.01 PBS (pH 7.4) followed by 4 % paraformaldehyde in 0.1 M phosphate buffer (pH 7.4). The brains were postfixed for 3 h and cryoprotected in a gradual sucrose (10, 20 and 30 %). Blocks of the brains were sectioned in a coronal plane (50 [mu]m), mounted on gelatin-coated slides and processed for FluoroJade B (FJB) histochemistry. Sections were examined with an epifluorescence microscope Olympus Provis AX70 using FITC filter sets. Small number of FJB-positive neurons was found in the dorsal striatum of 12-day-old animals in majority of survival intervals. Fifteen-day-old pups exhibited FJB-positive cells only 8 and 12 h after SE. Moderate to large number of degenerated neurons was found in majority of survival intervals in 18-day-old and older animals; positive neurons were more common after longerthan after shorter intervals. Degenerating neurons prevailed in dorsolateral margin and central area of rostral half of striatum. In contrast, FJB-positive neurons were located in medial part adjoining to pallidum and in basal part of caudal half of striatum. Degenerating neurons were never found in medial as well as lateral segments of globus pallidus. Lithium-pilocarpine model of SE resulted in degeneration of neurons in dorsal striatum but not in globus pallidus. Main input and output structures of basal ganglia circuit responded thus differently to status epilepticus. (Supported by grant No.304/04/0464 of Grant Agency of the Czech Republic.)