SYNAPTOPHYSIN IMMUNOHISTOCHEMISTRY DENSITOMETRY MEASUREMENT IN RESECTED HUMAN HIPPOCAMPUS - IMPLICATION FOR THE ETIOLOGY OF HIPPOCAMPAL SCLEROSIS

Synaptophysin (SY) is a protein expressed at presynaptic vesicles. SY immunohistochemistry (IHC) was undertaken in surgically resected hippo campal specimens from 25 patients with intractable epilepsy. All were investigated with chronic ictal EEG videotelemetry, which showed a tem poral onset in each case, and all had normal magnetic resonance imagin g (MRI). The density of reaction product of SY IHC was used to generat e optical density (OD) measurements as an estimate of synaptic density in CA1 and CA4 fields (ODCA1 and ODCA4), and inner third and outer tw o-thirds of the molecular layer of the dentate gyrus (ODIML and ODOML) . There was significant correlation between ODCA1 (r = 0.619, P = 0.00 1) and ODCA4 (r = 0.639, P = 0.001) and onset age of epilepsy. There w as no correlation between ODCA1 and duration of epilepsy. There was co rrelation between ODCA4 and duration (r = - 0.412, P = 0.041), but par tial correlations showed no significant correlation between ODCA4 and duration when controlling for onset, although correlation between ODCA 4 and onset when controlling for duration remained significant (r = 0. 536, P < 0.01). Univariate ANOVA revealed onset age to be the only pre dictor of ODCA1 and ODCA4. Chronological age and duration were not pre dictors. There was no correlation between ODIML or ODOML and either on set age or duration. ODIML and ODOML were not predicted by onset age, duration or chronological age. These findings support the hypothesis t hat the major cause of hippocampal sclerosis is an age specific insult rather than the result of repeated seizures. (C) 1998 Elsevier Scienc e B.V. All rights reserved.