NEURONAL CYCLIN EXPRESSION IN THE HIPPOCAMPUS IN TEMPORAL-LOBE EPILEPSY

This study used immunocytochemistry to explore the expression of cycli ns A, B, D, and E and the apoptosis-associated Bax: protein in hippoca mpal sub-fields of 35 lobectomy specimens with medial temporal lobe sc lerosis removed for the treatment of temporal lobe epilepsy (TLE), 2 a ge-matched controls, and 2 elderly patients suffering from drug-respon sive epilepsy. Cyclins A and D were not detected at all in neuronal nu clei, Cyclin E was only rarefy detected in neuronal nuclei in drug-con trolled and TLE groups and in controls. Cyclin B was expressed in sign ificantly more neuronal. nuclei in the hippocampi in TLE than in the o ther groups studied. The nuclear expression of these proteins suggeste d that neurons had reentered the cell division cycle and reached the G (2) phase. The nuclear expression of cyclin B in the hippocampus from these patients was accompanied by neuronal cytoplasmic expression of t he death-related Bar protein. We interpret these neuronal findings as evidence of cell cycle disturbances and a possible apoptotic mechanism of hippocampal neuronal cell death in TLE. (C) Academic Press.