Isoflurane Affects Astrocytes And The Result Of Behavior Test In Neonatal Rats At Juvenile Age Abstract

Chapter1Isoflurane affects morphology of astrocytes and the expression of GFAP and EAAT2in neonatal ratsBackgoundAstrocytes play a significantly role in the pathogenesis of neurodevelopmental disorders. Despite recent studies have implicated prolonged exposure to isof lurane increased neuronal apoptotic cell death, very little is known about whether morphology and important functions of astrocytes has been influenced, whether EAAT2on the surface of astrocytes is disrupted in neonatal animals, whether memory and learning ability of rats has been affected.MethodsSeven-day-old littermates of Wistar rats were randomly assigned to a6-hour exposure to either1.1%isoflurane or room air (n=40). Animals were euthanized12h,24h,3d and7d after exposure.The brain sections were double-stained for anti-GFAP and anti-EAAT2markers. The Optical Density of GFAP and EAAT2was quantificated in the cortex and hippocampus at12h,24h,3d and7d after exposure by the Image J programme.ResultsLittermates exposure to isoflurane significantly lead to a decrease of GFAP in the cortex and the hippocampal region at12h,24h after exposure, but not at3d and7d. The EAAT2in the cortex and the hippocampal region decreased significantly at3d. There was no statistically significant difference in the number of actived and depressed form of astrocytes compared to control group.The number of depressed astrocytes of neonatal rat hippocampus increased significantly at24h after anesthesia, but there was no statistically significant differences in the7d after anesthesia, although there was some decline compared with the control group. The number of activated astrocytes, although increased at7d after anesthesia, but there was no statistically significant difference compared with the control group.The fluorescence optical density of EAAT2and GFAP in neonatal rat cortex at12h,24h significantly decreased after anesthesia, and there was a significantly difference compared with the control group at3d after anesthesia according to fluorescent double-labeling. The optical density of GFAP in neonatal rat cortex slightly elevated but there was no statistically significant difference compared with the control group. Merge part of the immune fluorescence staining intensity in the region began to decline significantly after anesthesia until7d after anesthesia.The fluorescence optical density of GFAP in neonatal rat hippocampus significantly decreased at24h,3d, there was a statistically significant difference compared with the control group;the optical density of EAAT2expression were slightly decresead, there was no significant difference when compared with the control group, Merged part of the immune fluorescence staining in the region began to decline significantly after anesthesia, fluorescence optical density of Merged part has not been restored at7d.The result of western-blot showed that isoflurane exposure led to slightly decreases in EAAT2and GFAP in neonatal rat cortex at12h and24hours after anesthesia relative to control group, there was no significant change compared with the control group. However3d and7d after anesthesia the expression of EAAT2and GFAP decreased significantly, and there is a statistically significant difference compared with the control group.The expression of EAAT2in neonatal rat hippocampal at12h and24hours after anesthesia did not change significantly,3d and7d after anesthesia it decreased significantly compared with the control group. The expression of GFAP decreased significantly at12h and7d, there was no statistically significant difference (p<0.05) compared with the control group.Conclusions(1) In7-day-old mice, long-lasting isoflurane exposure led to the increase of depressed astrocytes in cortex and hippocampus and decrease of EAAT2expression on its surface.(2) Isoflurane can reduce the newborn rat cortex and hippocampus EAAT2and GFAP expression. Chapter2The effect of prolonged isof lurane exposure to the the memory and learning ability at juvenile ageObjectiveThe aim of the study was to explore the effects of prolonged exposure of isoflurane on the memory and learning ability of rats at juvenile age.MethodsSeven-day-old littermates of Wistar rats were randomly assigned to a6-hour exposure to either1.1%isof lurane group (I group, n=20)or control group (C group, n=20). Spatial memory and learning of the littermates were examined with the Morris Water Maze (Hidden Platform test and Probe Trial test) at juvenile age5weeks later.ResultsCompared with control group, there was no statistical difference in the mortality between groups. The escape latency of isoflurane group was delayed slightly at the first three days but there was no statistical differences. There were no difference about the time in the target quadrant, the first time through the platform, the number of cross platform and search strategies in isoflurane group compared with the control group. Littermates exposure to isoflurane did not impair subsequent juvenile spatial reference memory and learning ablitity.Conclusions:These results showed that in7-day-old rats, prolonged isoflurane exposure does not impair memory and learning ability in the juvenile rat.