Serotonin Receptors in Seizure Disorders

Objective: to study serotonin receptors in patients with localization-related epilepsy. Studies in experimental animals have suggested that: Serotonin is an anticonvulsant neurotransmitter in a number of seizure models; its anticonvulsant action is mediated by activation of 5-HT(1A) receptors; drugs with antiepileptic effects may release 5HT or block reuptake, and these mechanisms appear to be related to their therapeutic effect. 5HT(1A) receptors are abundant in regions such as entorhinal cortex, hippocampus, and temporal neocortex, where epileptogenic zones are frequently found. Considerable evidence from literature indicates that alterations in 5-HT(1A) receptors exist in experimental models of both generalized and complex partial seizures. There is little data on changes in 5-HT receptors in epileptic patients. Study population: 75 patients with localization-related epilepsy and 20 normal controls, aged 18-60. Design: Using a new PET compound which is a highly selective 5-HT(1A) silent antagonist referred to as (18)FCWAY, we will attempt to detect abnormalities in serotonin receptors in vivo in patients with epilepsy. The patients will have (18)FCWAY serotonin receptor studies (which include (15)H2O-CBF PET) and high resolution T1-weighted MRI for co-registration. (18)FDG-PET will be performed in the patients as part of seizure focus localization. We will also test subjects for the serotonin transporter polymorphism associated with depression, and perform a standard depression battery. Outcome measures: 5HT-1A receptor binding and Glucose metabolism measured by PET.