Effects Of Long-term Low Concentration Sevoflurane Exposure On Learning And Memory Functions In Adult Mice

BACKGROUND: Current animal studies have shown that volatile anaesthetics such as sevoflurane,isoflurane and intravenous anaesthetics such as propofol can cause apoptosis in monkeys and newborn rodents,resulting in neurological impairment of learning and memory functions.Clinical studies have also found that single exposure to anaesthesia does not affect children’s learning and reading abilities,but secondary or repeated exposure significantly increases the risk of learning disabilities.Sevoflurane is a commonly used inhalation anaesthetic that inevitably leads to anaesthetic gas leakage during anaesthesia administration,and it is of concern to anaesthetists and operating theatre staff whether prolonged exposure to low concentrations of sevoflurane may lead to impairment of their learning memory functions.Current studies on the effects of sevoflurane on learning memory function have mostly focused on anesthetic doses and the developing brain,while few studies have been reported on the related effects of low-level sevoflurane exposure in operating room staff.Objective: The study investigates the effects of long-term low-concentration sevoflurane exposure on learning memory function in adult mice and provides a reference for the safety of occupational exposure and related occupational protection for anaesthesiologists and operating theatre staff.Methods: A total of 75 healthy adult KM mice were randomly divided into 3 groups(n=25):control group(group A),0.1% sevoflurane group(group B)and 0.3% sevoflurane group(group C).At9:00-10:00 am daily,group A was exposed to air,and groups B and C were exposed to 0.1% sevoflurane +air and 0.3% sevoflurane + air,respectively,for 1 hour.After four weeks and twelve weeks of exposure,respectively,the three groups of mice were subjected to the place navigation test PNT and the spatial probe test SPT using the Morris Water Maze MWM.After the last MWM experiment,three mice in each group were randomly selected to undergo Td T-mediated d UTP Nick-End Labeling TUNEL staining to detect apoptosis,and ten mice were randomly selected to undergo enzyme linked immunosorbent assay ELISA.The expression of β-site APP cleaving enzyme1 BACE-1 in the hippocampus was detected by western-blot Wb and β-amyloid peptide Aβ was detected by ELISA.Results:1.Results of the two MWM experiments: the differences in the evasion latency(escape latecy EL),residence time in the original platform quadrant and the number of times crossing the original platform in the three groups of mice at week 4 and week 12 of the MWM experiment were not statistically significant(P > 0.05).2.The differences in apoptosis,Aβ concentration,and BACE-1 expression in the hippocampus of the three groups of mice were not statistically significant(P>0.05)Conclusion1、Long-term exposure of adult mice to 0.1% and 0.3% sevoflurane did not result in significant impairment of learning and memory functions in mice.2、Long-term exposure of adult mice to 0.1% and 0.3% sevoflurane did not significantly affect the apoptosis of their brain cells and the expression of Aβ and BACE-1.