Abstracts

Rationale: The main goal of the present study was to evaluate binding to serotonin in the neocortex surrounding the epileptic focus of patients with Mesial Temporal Lobe Epilepsy (MTLE). Methods: Binding to 5-HT, 5-HT1A, 5-HT4, 5-HT7 receptors and serotonin transporter (5-HTT) in T1-T2 gyri of 15 patients with MTLE and their correlations with clinical data, neuronal count and volume were determined. Autopsy material acquired from subjects without epilepsy (n=6) was used as control. Results: The neocortex from MTLE patients demonstrated decreased cell count in layers III-IV (21%). No significant changes were detected on the neuronal volume. Autoradiography experiments showed the following results: reduced 5-HT and 5-HT1A binding in layers I-II (24% and 92%, respectively); enhanced 5-HT4 binding in layers V-VI (32%); no significant changes in 5-HT7 binding; reduced 5-HTT binding in all layers (I-II, 90.3%; III-IV, 90.3%, V-VI, 86.9%). Significant correlations were found between binding to 5-HT4 and 5-HT7 receptors and age of seizure onset, duration of epilepsy and duration of antiepileptic treatment.Conclusions: The present results support an impaired serotoninergic transmission in the neocortex surrounding the epileptic focus of patients with MTLE, a situation that could be involved in the initiation and propagation of seizure activity. Supported by CONACyT grant (45943-M).