Effects of dexmedetomidine on the learning disorder caused by sevoflurane and on the expression of synaptophysin in young rats

doi:10.3969/j.issn.1002-7386.2014.20.005

Abstract：Objective To investigate the effects of dexmedetomidine on the dysfunction of memory and learning and the expression of synaptophysin as well as post synaptic density 95 ( PSD-95 ) in hippocampus caused by sevoflurane in young rats.Methods Ninety Sprague-Dawley rats ( 7-day age ) were randomly divided to four groups , control group sevoflurane group,dexmedetomidine group and sevoflurane +dexmedetomidine group ( Sev +Dex group ) .The rats in sevoflurane group inhaled 2%sevoflurane for 4 hours,the rats in dexmedetomidine group received dexmedetomidine 25μg/kg by intraperitoneal injection,the rats in Sev +Dex group inhaled 2% sevoflurane after intraperitoneal injection for 4 hours.The levels of synaptophysin in hippocampus ,PSD 95 and p mammalian target of rapamycin ( p-mTOR ) protein and mRNA expression were detected by Western Blot and RT-PCR at 1,7 days after anesthesia.The abilities of memory and learning were evaluated by using Morris Water Maze Test after 5 weeks.Results The speed of learning in sevoflurane group was decreased ,as compared with that in control group, however, no obvious effect was found in dexmedetomidine group and Sev +Dex group.Both sevoflurane and dexmedetomidine decreased the expression levels of synaptophysin and PSD 95 protein and mRAN,moreover, dexmedetomidine could obviously relieve the inhibition effect of sevoflurane on the expression of these proteins .The three drugs could all decrease the expression level of p-mTOR protein and mTOR mRAN.Conclusion Dexmedetomidine can relieve the inhibition effect of sevoflurane on the expression of synaptophysin and PSD 95 in hippocampus of young rats and can improve the dysfunction of memory and learning after sevflurane anesthesia ,however ,which is not performed through p-mTOR pathway .