Subanesthetic isoflurane abates ROS-activated MAPK/NF-κB signaling to repress ischemia-induced microglia inflammation and brain injury

Abstract

Isoflurane (ISO) elicits protective effects on ischemia-induced brain injury. We investigated whether sub-anesthetic (0.7%) ISO post-conditioning attenuates the inflammation and apoptosis in oxygen-glucose deprivation (OGD)-insulted co-cultures (microglia and neurons) in vitro and the brain injury of the middle cerebral arterial occlusion (MCAO) rat. We demonstrated that ISO augmented the viability of OGD-treated microglia and neurons. ISO reduced the expression and activation of COX2 and iNOS in OGD-challenged microglia. ISO repressed the production of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-8, and monocyte chemoattractant protein-1 in OGD-exposed microglia. ISO also decreased nucleosomal fragmentation and caspase-3 activity but increased mitochondrial membrane potential in OGD-stimulated microglia and neurons. Mechanistically, ISO suppressed OGD-induced microglial inflammation by blocking ROS-regulated p38 MAPK/NF-κB signaling pathway and hampered OGD-triggered microglial apoptosis in a ROS- or NO-dependent fashion. In vivo results with MCAO rats were partly consistent with the in vitro observation. These findings indicate that sub-anesthetic ISO post-conditioning abates the inflammation and apoptosis in OGD-stimulated rat microglia and the apoptosis of OGD-exposed neurons and the brain injuries of MCAO rats, suggesting it as a potentially effective therapeutic approach for ischemic brain damages.