Propofol Increases GABA Concentration and Decreases Regional CBF in the Thalamus an In-Vivo 1H MRS/MRI Study in Normal Human Volunteers

Maolin Qiu¹, Ramachandran Ramani², Magret Rose², R. Todd Constable¹

GABA is the main inhibitory neurotransmitter in the brain. In-vitro studies have shown it plays an important role in anesthesia introduced by Propofol. The anesthesia state could be achieved by the potentiation of the GABAA receptor, facilitation of the GABA release, and regulation of the ambient GABA level. Most reports investigating the actions of general anesthetics on their targets are based on In Vitro data. Using both MRI and MRS, we have measured the resting-state regional CBF for the whole brain and the GABA and glutamate/glutamine concentrations in the thalamus in healthy volunteers. Our results show the thalamus is a region strongly influenced by Propofol anesthesia. GABA plays a major role in achieving anesthesia. This study supports the hypothesis that the thalamus is the key structure in the brain whose function is altered upon administration of the anesthetic agent Propofol.