Changes in central 5-HT1A receptor binding in mesial temporal epilepsy measured by positron emission tomography with [11C]WAY100635

SummaryObjectiveThe possible involvement of the brain 5-HT1A receptor in epilepsy has been indicated in animal seizure models. Recent in vivo neuroimaging studies demonstrated decreased 5-HT1A receptor binding in epilepsy. Using positron emission tomography (PET) with [11C]WAY100635, we investigated 5-HT1A receptor binding in patients with mesial temporal lobe epilepsy and aimed to clarify the involvement of the brain 5-HT1A receptor system in epilepsy.MethodPET measurements with [11C]WAY100635 were performed on 23 healthy volunteers and 13 patients who were diagnosed with mesial temporal lobe epilepsy based on clinical symptoms and electroencephalogram (EEG) findings. They had non-lesional mesial temporal lobe epilepsy with unilateral EEG foci and no hippocampal atrophy on magnetic resonance imaging. The binding potential (BP) of [11C]WAY100635 was calculated by the reference tissue model method. Data were analyzed for each region of interest (ROI) and on a voxel-by-voxel basis by statistical parametric mapping (SPM) system.ResultsROI and voxel-based analyses consistently demonstrated that 5-HT1A receptor BP was significantly decreased in the temporal lobe, hippocampus and amygdala on the ipsilateral side of the EEG focus compared to controls. In addition, decreased 5-HT1A receptor BP was also observed on the contralateral side of the amygdala.Conclusion5-HT1A receptor binding in patients with mesial temporal lobe epilepsy decreased predominantly in the ipsilateral mesial temporal lobe structures but also in the contralateral side. The imaging of 5-HT1A receptor binding by PET detects functional changes of the limbic system in mesial temporal lobe epilepsy, proving to be a sensitive and useful method.