Effects of combination of mild hypothermia and sevoflurane on oxygen-glucose deprivation injury in rat hippocampal slices

Objective To investigate the effects of mild hypothermia combined with sevoflurane on oxygen-glucose deprivation injury in rat hippocampal slices. Methods Male SD rats weighing 80-100 g were anesthetized with ether and decapitated. The hippocampus were removed and sagittally sliced (400 μm thick) and placed in artificial cerebrespinal fluid (ACSF) aerated with 95% O2-5% CO2. Thirty-two hippocampal slices were randomly divided into 4 groups (n=8 each): group Ⅰ OGD;group Ⅱ sevoflurane (Sev);group Ⅲ mild hypothermia(MH) and group Ⅳ MH + Sev. In group Ⅰ and Ⅲ , the hippocampal slices were perfused with glucose-free ACSF and aerated with 95%N2-5%CO2 for 14 min at 37℃ and 32℃ respectively. In group Ⅱ and Ⅳ, the hippocampal slices were perfused with oxygenated, glucose-containing ACSF saturated with 4% sevoflurane for 14 min, then perfused with oxygen/glucose-deficient ACSF saturated with 4% sevoflurane at 37℃ and 32℃ respectively. Electrophysiological technique was used to record the amplitude of orthodromic population spike (OPS) in the stratum pyramidale of CA1 region during OGD and 1h rcoxygenation.The release rate of LDH was determined using chromatometry. Results Compared with group Ⅰ , the disappearance time of OPS was significantly prolonged, the recovery amplitude of OPS was significantly increased in group Ⅱ and Ⅲ and the release rate of LDH was significantly decreased in group Ⅲ (P<0.05 or 0.01). Compared with group Ⅲ , the disappearance time of OPS was significantly prolonged, the recovery amplitude and rate of OPS were significantly increased and the release rate of LDH was significantly decreased in group Ⅳ (P<0.05 or 0.01). Compared with group Ⅱ, the disappearance time of OPS was significantly prolonged, the recovery amplitude and rate of OPS were significantly increased and the release rate of LDH was significantly decreased in group Ⅳ (P<0.05 or 0.01). Conclusion Combination of mild hypothermia(32℃) and 4% sevoflurane can attenuate OGD injury in rat hippecampal slices. Key words: Hypothermia,induced; Anesthetics, inhalation; Anoxia; Hippocampus