Saccadic eye velocity after selective GABAergic treatment with tiagabine in healthy volunteers

Abstract

Background: Saccadic eye velocity (SEV) has been shown to be a reliable neurophysiological tool for the assessment of γ-aminobutyric acid GABAA receptor sensitivity. Administration of benzodiazepines targeting the GABAA receptor decreases SEV in healthy volunteers. Tiagabine is a new antiepileptic drug which acts via selective blockade of GABA reuptake. Therefore, we examined the effects of tiagabine on saccade parameters. Methods: SEV was analyzed in 8 healthy volunteers before and after 7 days of tiagabine treatment. Subjects received tiagabine in a daily dose of 15 mg. Saccades were measured using a noninvasive infrared oculographic device. Amplitude, latency, and SEV were analyzed as a function of treatment and target eccentricity. Results: SEV and saccade latency increased with target amplitude. Treatment with tiagabine had no significant effect on SEV and saccade amplitude. A trend was found for increased latencies after tiagabine. Conclusion: In contrast to findings with benzodiazepines, tiagabine treatment had no impact on SEV in healthy volunteers. The subchronic tolerance effects or the different site of action on the GABAA/BZD receptor complex may account for this deviating profile. Copyright © 2005 S. Karger AG.