| China has a large population,there are millions of children suffer general anesthesia surgery and treatment every year.Whether the anesthetic has any impact on the developmental children’s intelligence?Whether the anesthetic lead to learning disability?This has been a concern of many parents,also this field of anesthesia have been controversial issues.Cognition and learning as the complicated ability of human,can be effected by a various factors;Different kinds of anesthetics have different impacts by different mechanisms.Some clinical trials have indicated that the anesthetics can impact the children’s cognition function,however,the accuracy of data is still remained to be doubtful.In recent years,lots of animal experiments found that the anesthetics exposed common clinical application could cause abnormal development of neural cells in brain which induced the cognitive dysfunction and decline of learning ability in the long time.Propofol is the most common general anesthetics applied to children.It is popular in anesthetist to quick induction,short duration, rapid recovery and so on,commonly used in short pediatric surgery and invasive medical examination.Previous animal experiments indicated that propofol had the neurotoxic effects by enhancing the action of γ-amino butyric acid(GABA) through the GABA receptor and blocking the N-methyl- D- aspartate(NMDA) glutamate receptor.Propofol is GABA receptor agonist, if there be a corresponding neurotoxicity?The study remains limited.It remains controversial about the mechanisms that propofol lead to learning discordered in the long time.As is well-known,the brain is the most important functional organ,which is the main component of spinal animal’s central nervous system and control motion,induce sensation and performing advanced function. It is well known that new neurons are produced in the postnatal hippocampus and play a impoetant role in the cognitive processes such as learning and memory.The cortex is mainly composed of neurons,and achieve the function of information transmission by lots of neural circuits that made up of abundant neurons.The differentiation discorder of hippocampal dentate gyrus neural stem cell in puberty and the decline of mature neurons in cortex and the exception of dendritic growth,which may have an important influence in cognition,learning and memory in the long term.Therefore,we focus on the influence of brain hippocampal and cortical neural cells in pubertal mice with propofol administration,to figure out the mechanisms of regulating the function of cognition and learning in the long time.In recent years,some studies indicated that the cognitive dysfunction caused by general anesthetics correlated with the time,duration and dose of exposed anesthetics.After exposure of anesthetics can lead to relevant neural stem cells apopyosis in the rodent animal 2 weeks after birth.P7 is the height of neural cells in the development of rodent animals,in this period,exposure of anesthetics can lead to relevant apoptosis climax.Recently,some studies indicated that propofol can influence the survival of newborn neuron in brain hippocampus of adult animals,intervene the maturity of neural cells.Propofol can significantly decrease the amount of mature neural cells differentiated by hippocampal dentate gyrus neural stem cell in mice at 3 months,and differentiated into astrocyte.This change influence the process of mature neuron integrate into neural circuits,lead to transmission disorder between neural cells.As for pubertal animals,whether the propofol can trigger temporary information conductive obstruction,influence the formation of neural circuits,and lead to long-term learning dysfunction by intervening neural stem cells proliferation and differentiation in hippocampal and cortical region of brain are still unclear.Research methods:The research subjects: C57 mice were received propofol intraperitoneally on P7 for 3 days(once per day at a dose of 30mg/kg or 60mg/kg) or the same volume of intralipid as a control.Immunohistochemical detection:Hippocampal region:DCX/Brdu double labeled,to observe neural stem cell proliferation and proliferative cells into mature neurons with propofol administered;NeuN staining, to observe the number of mature neuron in hippocampal region;Golgi staining,to observe the neuron dendritic spine morphologic change in hippocampal region.Cortical region:MAP2B protein labeled,to observe the density of dendritic spine of cortical cones; Golgi staining,to observe dendritic spine morphology of cortical cones;NeuN staining, to observe the number of mature neuron in cortical region;GFAP staining,to observe to the number of astrocyte in cortical region.Research results:1. Double staining with BrdU(markers for cells proliferation) and DCX(markers for migrating neuroblasts or newly formed neurons) to observe the newborn neural stem cells and differentiate into mature neurons in hippocampal dentate gyrus. Fluorescence double-labeled revealed that there was no statistical difference in the number of Brdu+ cells at 30mg/kg,but decrease significantly at 60mg/kg; And there was no statistical difference in the number of Brdu+ / DCX+ cells at 30mg/kg,but decrease signally at 60mg/kg.There exist differences in between dosage groups,60mg/kg group has a significant difference.2. NeuN staining revealed that the number of hippocampal dentate gyrus mature neuron with different dose of propofol. Fluorescence labeled indicated that there was no difference in number of NeuN+ cells in the same region and area of hippocampal dentate gyrus compared to control group at 30 mg group;At 60 mg group,the number of cells decreased but no statistical difference.3. Golgi staining revealed that the morphology of dendritic spines of hippocampal dentate gyrus granule neurons. observed in Tsai X100 microscope to count the sum of granule cells dendritic spines with the same length,at 30 mg group,there was a significant decrease in sum of dendritic spines compared to control group,so does 60 mg group.Mature mushroom spines decrease significantly both at 30 mg and 60 mg groups as compared with control group;lanky dendritic spines increase significantly both at 30 mg and 60 mg groups as compared with control group;map dendritic spines have no significant difference in control group,30 mg group, and 60 mg group.4. Immunofluorescence:GFAP can label the number of astrocyte in cerebral cortex:there is no significant difference between 30 mg and control groups at unit area in GFAP labeled astrocyte,so does 60 mg group.5. Immunofluorescence:NeuN can label the number of mature neuron in cerebral cortex There is no significant difference between 30 mg group and control group at unit area in NeuN labeled mature neuron,so does 60 mg group.6. MAP2 B can label the dendrite of cortical cones.There is no difference in expression of MAP2 B among groups by using Optical density analytic statistics compared to control group.There is no significant difference in expression of MAP2 B at 30 mg group by using Optical density analytic statistics,but there is a signal decline in expression of MAP2 B at 60 mg group.7. Golgi staining revealed the morphology of dendritic spine of cerebral cortical cones of mice.There is no significant difference in the amount of dendritic spine between 30 mg group and control group,there is a significant decline in mature mushroom dendritic spines compared to control group;the amount of dendritic spines decreased significantly at 60 mg group compared to control group,so does the mature mushroom dendritic spines.Research conclusions:1. The suppression of pubertal mice hippocampal dentate gyrus neural stem cell differentiating by using propofol is correlated with the dosage of propofol administration.2. Propofol administration of low-dosage and only one-time has no significant influence in the amount of mature neuron.3. The influence of the number and morphology of granule cells in pubertal mice hippocampal dentate gyrus and the cones in cerebral cortex are correlated with the dosage of propofol administration. |
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