Increased expression of caspase 2 in experimental and human temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is often caused by a neurodegenerative brain insult that triggers epileptogenesis, and eventually results in spontaneous seizures, i.e., epilepsy. Understanding the mechanisms of cell death is a key for designing new drug therapies for preventing the neurodegeneration associated with TLE. Here, we investigated the expression of caspase 2, a protein involved in programmed cell death, during the course of epilepsy. We investigated caspase 2 expression in hippocampal samples derived from patients operated on for drug refractory TLE. To understand the evolution of altered-caspase 2 expression during the epileptic process, we also examined caspase 2 expression and activity in the rat hippocampus after status epilepticus-induced acute damage, during epileptogenesis, and after the onset of epilepsy. Caspase 2 expression was enhanced in the hippocampal neurons in chronic TLE patients. In rats, status epilepticus-induced caspase 2 labeling paralleled the progression of neurodegeneration. Proteolytic activation and cleavage of caspase 2 was also detected in the rat brain undergoing epileptogenesis. Our data suggest that caspase 2-mediated programmed cell death participates in the seizure-induced degenerative process in experimental and human TLE.