Repeated (daily) treatment with FTY720 protects from kainic acid (KA)-induced neurodegeneration in vivo. (A) Schematic timeline of experimental protocol. FTY720 or vehicle was ip injected (1 mg/kg) daily, starting 1 day before icv surgery up to 2 days thereafter. Animals received a single icv injection of KA alone (0.5 μg/2 μl) or in combination with FTY720 (1 μg/2 μl). Seizure score was evaluated post-surgery at 30-min intervals over a period of 2 h. On day 3 after icv injection, animals were sacrificed and brain tissues processed for immunohistochemical analysis. (B) Effect of daily FTY720 treatment on seizure-like behaviour induced by KA icv injection. Seizure was scored as described in the ‘Methods’ section, with the higher score indicating greater seizure severity. The mean seizure score for KA group (n = 12, four independent experiments with 3 animals each) and KA + FTY720 group (n = 13, four independent experiments with ≥3 animals each) was plotted against time after icv. *P < 0.05 vs KA-treated group, Mann–Whitney test at any time point of recorded seizure score. (C, D) Quantification of the extent of the lesion in animal icv injected with KA (n = 11) and KA + FTY720 (n = 12) after Nissl’s staining. Eight slices per animal were evaluated. Area of the lesion and areas of CA3 and hippocampus were measured for each slice (mm2) in the ipsilateral side. The mean lesion area per animal was calculated and normalized to the mean CA3 or hippocampal areas (C, D). Only ipsilateral hemisphere was considered for the analysis. *P < 0.05 and **P < 0.01 vs KA-treated group, Student’s t test. All data are expressed as the mean ± SEM of n ≥ 11 animals for each experimental group (four independent experiments).