Acute and sustained isoflurane neuroprotection: The effect of culture age and duration of oxygen and glucose deprivation

Abstract

Objectives: Organotypic hippocampal slice (OHS) cultures provide the opportunity to dissect factors influencing volatile anaesthetic neuroprotective efficacy. It was hypothesized that three conditions—OHS culture age, oxygen glucose deprivation (OGD) duration and day of evaluation for cell death after OGD—influence isoflurane's ability to provide acute and sustained protection against OGD-induced cell death.Methods: OHS were prepared from PND 9–11 rat pups and maintained in vitro for 0.5, 1, 2 or 3 weeks. The slices were exposed to OGD for 0, 10, 30, 60 or 90 minutes with or without 1.5% isoflurane. Sytox staining was used to determine the amount of cell death on post-OGD days 1, 3 and 7 and was compared to the amount of cell death in culture–age matched controls (no OGD).Results: The duration of OGD necessary to produce cell death was inversely related to culture age. All culture ages showed evidence of both acute and sustained neuroprotection, but the magnitude of protection depended on OHS culture age, duration of OGD and post-OGD day of evaluation. In 1 and 2-week old slices early isoflurane neuroprotection was best observed with 90 minutes OGD and late isoflurane protection was best observed with 10 minutes OGD.Conclusions: In OHS, acute and sustained isoflurane neuroprotection in OGD-induced cell death is dependent on the conditions being studied.