PhMRI of Brain Deactivation: Effects of the Antiepileptic Agent Tiagabine on Cerebral Haemodynamics
Gozzi A, Ceolin L, Schwarz A, Reese T, Bifone A, Crestan V
Centre of Excellence for Drug Discovery, Psychiatry, GlaxoSmithKline
The interpretation of negative responses in pharmacological MRI has been a contentious matter in recent literature. We have used MRI, Laser Doppler Flowmetry, and fluorescence quenching methods to measure the individual components of the response to a pharmacological challenge with Tiagabine, a GABAergic drug that lowers neuronal activity in the cortex. Tiagabine produced a marked cortical reduction in both rCBV and LDF, consistent with reduced local metabolism. However, a sustained increase in pO2 was observed, suggesting that during cortical GABAergic deactivation, tissue oxygen consumption decreases more than oxygen supply.