The Effect of Isoflurane on the Blood-Brain Barrier

Date(s) - 07/05/2013
3:00 pm

Christine Girard, Masters Student

The blood-brain barrier (BBB) is a complex structure that is comprised of tight junctions and their associated proteins, junction adhesion molecules, and astrocytic end-feet. These features aid in limiting the transport of certain molecules into the interstitial space in the brain and ensure that the integrity of the barrier is maintained. Alterations to these structures may result in BBB disruption and serves as the underlying cause of several central nervous system (CNS) disorders [1]. The effect of the anesthetic agent, isoflurane, on the permeability of the BBB remains unclear. In this study, we performed tail vein injections of Evans blue dye (EVB) in rats exposed to an hour of isoflurane (2% in oxygen) while monitored by an electroencephalogram (EEG), in order to investigate the effects of this volatile anesthetic on the BBB. Fluorescence microscopy was utilized to examine brain slices for traces of EVB, which appeared to be confined to vascularized regions within tissue, cerebrospinal fluid (CSF) spaces (fissures and ventricles), and brain parenchyma directly outside of regions containing CSF. The observation of EVB in CSF spaces and the surrounding brain parenchyma appears to be a direct result of leaky capillaries located within the choroid plexuses of cerebral ventricles. Brain tissue does not appear to contain EVB, indicative of an intact BBB. Thus, this study demonstrates isoflurane does not play a role in the partial or complete breakdown of the BBB.