Different effects of a single exposure or multiple exposures to sevoflurane on hippocampal structures in neonatal rats / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effects of a single exposure or multiple exposures with equivalent total duration of exposure to sevoflurane on the histological morphology and neurons ultrastructure changes in neonatal rats hippocampus CA1.Methods A total of 45 male Sprague-Dawley rats on postnatal day 7,weighing 14-18 g,were randomly divided into three groups (n=15 each): Control group (group C),single exposure to sevoflurane group (group SS),multiple exposures to sevoflurane group (group TS).In group SS,the rats inhaled 3% sevoflurane for 6 h on postnatal day 7.In group TS,the rats inhaled 3% sevoflurane for 2 h on postnatal day 7,8 and 9.In group C,the rats inhaled 60% oxygen on the corresponding day age.Rats were sacrificed and brain were seperated on postnatal day 14.CA1 pyramidal neurons pathological morphology and quantity changes were observed by Hematoxylin-Eosin (HE) and Nissl staining.In the meantime,transmission electron microscopy was used for observing neurons ultrastructure and measuring the thickness of the postsynaptic density and the length of the postsynaptic active area.Results Nissl staining and HE indicated that multiple exposures and a single 6 h exposure to sevoflurane resulted in severer neurons loss and sparse arrangement relative to group C (P<0.05),Multiple exposures to sevoflurane resulted in greater neurons loss compared with a single 6-h exposure (P<0.05).Transmission electron microscope indicated that damage of CA1 neuronal subcellular organelle induced by multiple exposures and a single 6 h exposure was severer compared with group C.Both multiple exposures and a single exposure lead to decreased thickness of the postsynaptic density and shorter length of the postsynaptic active area (P<0.05).Multiple exposures to sevoflurane caused greater damaged than a single exposure (P<0.05).Conclusion Both a single and multiple exposure to sevoflurane induced CA1 neurons loss and ultrastructure changes in neonatal rats.Compared with a single exposure,multiple exposures to sevoflurane resulted in greater neurons morphology injury.