Patterns of Hippocampal Neuronal Loss and Axon reorganisation of the dentate gyrus in the mouse pilocarpine model of temporal lobe epilepsy

Abstract

Patterns of hippocampal neuronal loss and rewiring of dentate gyrus (DG) were studied in pilocarpine mouse model of temporal lobe epilepsy. NeuN immunocytochemistry showed two patterns of neuronal damage: Type1 with partial loss and Type2 with compete loss of CA3 pyramidal neurons. Phaseolus vulgaris leucoagglutinin (PHA-L) tracing demonstrated at different rostrocaudal hippocampal segments, associational and commissural connections in DG changed differently between Type1 and Type2 mice. Calretinin immunopositive neurons in ventral hilus and its fibers in inner molecular layer remained in Type1 but disappeared in Type2 mice, which was supported by co-localization of cholera toxin subunit B with calretinin in the ventral hilus in Type1 but lost in Type2 mice. Sprouted PHA-L immunopositive boutons from DG were found in CA1 area to contact with surviving calbindin, calretinin, and parvalbumin neurons. The present study suggests different patterns of neuronal loss in CA3 area may link to different axon reorganizations in DG.