ApoE transiently regulates hippocampus amyloid-beta deposition to stable learning and memory ability in adult rats exposed in sevoflurane.

Abstract

Post-operative cognitive dysfunction (POCD) is a common central nervous system complication after surgery. Inhaled anesthetic sevoflurane is thought to have harmful effects on the developing and aged nerves, but its effects on adults' nervous system are less studied and the mechanism is not clear. Male adult rats were divided into control group and sevoflurane group. Rats from sevoflurane group were received 3.2% sevoflurane + carrier gas (1L/min O2+1L/min air) for 2h, while control group received carrier gas for 2h. Each group was subsequently divided into 3 subgroups according to the Day 1, Day 3, Day 7 after sevoflurane anesthesia. Morris Water Maze, amyloid-beita (Abeta) and apolipoprotein E (ApoE) mRNA in hippocampus were analyzed. Then, adult ApoE-/- rats were also divided into control group and sevoflurane group. Each group was divided into 3 subgroups according to Day 1, Day 3 and Day 7. Abeta mRNA and protein expression in hippocampus were analyzed. Compared with the control group, hippocampal Abeta mRNA and protein expression in rats from sevoflurane group significantly increased in hippocampus on Day 7, while ApoE mRNA and protein expression increased on Day 1 and Day 3. There was no difference in times of crossing platforms, time during platform, times across platform quadrant and time percent during platform quadrant between each group. Compared with the control group, hippocampal Abeta and ApoE-/- rats in sevoflurane group did not change. ApoE modulates hippocampal Abeta deposition and stabilizes learning and memory ability in adult rats after sevoflurane exposure, but this effect is not constant.