| Objectives:Propofol,one of the most commonly used intravenous anesthetic,is widely used in surgery and painless diagnosis.In addition to its anesthetic properties,it is also reported that it could induce neuroprotective and developmental neurotoxicity.This study will investigate the effect of propofol on the proliferation and differentiation of hippocampal neural stem cells(NSCs)in adult rats from the molecular level,and further explored the effect of propofol on learning and memory performance in adult rats,we aim to reveal the protection of hippocampal NSCs proliferation and differentiation,and to explore the protection and treatment of brain damage induced by anesthesia.Methods:The primary cultured hippocampal NSCs were selected in vitro and exposed for 24 h to propofol at 0,5,50,100μM.Different sites were selected for observation and comparing the diameters of neurosphere that exposed after propofol,and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)was used to detect viability of NSCs.Adult male Sprague-Dawley rats were selected in vivo and continuous intraperitoneal injection with propofol 30mg/kg(group Prop30),propofol 60mg/kg(group Prop60),and propofol 120mg/kg(group Prop 120)once daily for 5 days,a does of 6mL/kg normal saline(group N)or fat emulsion(group V)was used to construct a model.Morris Water Maze(MWM):to determine the effects of propofol on learning and memory performance in adult rats after propofol,including the directional navigation ability,as the escape latency,and spatial exploration ability,as the number of crossing over the previous platform and the percentage of time in the target quadrant.Immunofluorescence staining(IF):the number of Nestin+Ki67+ cells,double IF markers,were used to observe the effect of propofol on the proliferation of hippocampal dentate gyrus NSCs;the number of β-Tubulin Ⅲ+ cells was used to observe the changes of neurogenesis in the hippocampus;Nestin and Notch3,double IF markers,were used to locate the expression of Notch3.Real-time quantitative polymerase chain reaction(qPCR)and western blotting(WB):the effects of propofol on the expression of Notch3 mRNA and protein in the hippocampus.WB:the expression of Hesl and Hes5 in hippocampus.Results:1.The escape latency of all the rats in MWM showed a decreasing trend.There was no significant difference between group V,group Prop60,and group N on the escape latency.The escape latency of group Prop 120 was significantly prolonged,and that of group Prop30 was significantly prolonged,compared with group N respectively.On the percentage of time in the target quadrant and the number of crossing over the previous platform,there was no significant difference between group V,group Prop30,group Prop60 and N group,but the memory performance of group Prop 120 was lower than that of group N.2.In vivo,the number of Nestin+Ki67+ cells in the hippocampal dentate gyrus of group Prop60 was significantly increased compared with group N,and the number of Nestin+Ki67+ cells in group Prop 120 was significantly decreased compared with group N.In vitro,the diameter of neurospheres was increased at 50μM propofol exposure compared with OμM propofol exposure.Although there was no statistically significant difference between propofol exposure at 100μM and OμM,the diameter had a decreasing trend.The MTT showed that the cell viability was weakened at the concentration of propofol up to 100μM,but it significantly enhanced when NSCs were exposed to 50μM propofol.3.Compared with group N in vivo,the number of β-Tubulin III+ cells in group Prop60 was increased,which was statistically significant,and the number ofβ-Tubulin III+ cells in group Prop 120 was lower than that in group N.4.After continuous intraperitoneal injection of propofol for 5 days,NSCs of hippocampal dentate gyrus expressed Notch3 in adult rats.The relative expression of Notch3 in group Prop60 was significantly higher than that in group N.The relative expression of Notch3 in group Prop 120 had a decreasing trend compared with group N,but there was no significant difference in the expression of Notch3 between group Prop120 and group N.5.The expression of Hes1 and Hes5,which were the target genes of Notch signaling pathway and detected in hippocampus after propofol,showed that there was no significant difference in mRNA and protein expression of Hesl compared with group N.Compared with group N,the expression of Hes5 in group Prop60 was significantly higher.The expression of Hes5 was reduced in the group Prop 120 than that in group N.Conclusions:1.Continuous intraperitoneal injection of propofol may impair learning and memory performance in adult rats.2.Propofol at a dose of 60mg/kg had a less damage to learning and memory performance in adult rats.3.Propofol at a dose of 60mg/kg may via Notch3-Hes5 signaling pathway to promote the proliferation of NSCs and neurogenesis in hippocampal dentate gyrus of adult rats,which diminish the damage of propofol on learning and memory performance. |
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