Isoflurane preconditioning improves short-term and long-term neurological outcome after focal brain ischemia in adult rats

Isoflurane preconditioning improved short-term neurological outcome after focal brain ischemia in adult rats. It is not known whether desflurane induces a delayed phase of preconditioning in the brain and whether isoflurane preconditioning-induced neuroprotection is long-lasting. Two months-old Sprague–Dawley male rats were exposed to or were not exposed to isoflurane or desflurane for 30 min and then subjected to a 90 min middle cerebral arterial occlusion (MCAO) at 24 h after the anesthetic exposure. Neurological outcome was evaluated at 24 h or 4 weeks after the MCAO. The density of the terminal deoxynucleotidyl transferase biotinylated UTP nick end labeling (TUNEL) positive cells in the penumbral cerebral cortex were assessed 4 weeks after the MCAO. Also, rats were pretreated with isoflurane or desflurane for 30 min. Their cerebral cortices were harvested for quantifying B-cell lymphoma-2 (Bcl-2) expression 24 h later. Here, we showed that pretreatment with 1.1% or 2.2% isoflurane, but not with 6% or 12% desflurane, increased Bcl-2 expression in the cerebral cortex, improved neurological functions and reduced infarct volumes evaluated at 24 h after the MCAO. Isoflurane preconditioning also improved neurological functions and reduced brain infarct volumes in rats evaluated 4 weeks after the MCAO. Isoflurane preconditioning also decreased the density of TUNEL-positive cells in the penumbral cerebral cortex. We conclude that isoflurane preconditioning improves short-term and long-term neurological outcome and reduces delayed cell death after transient focal brain ischemia in adult rats. Bcl-2 may be involved in the isoflurane preconditioning effect. Desflurane pretreatment did not induce a delayed phase of neuroprotection.