| Objective:To observe the changes of neuroethology,apoptosis of hippocampal neurons,expression of Bax/Bcl-2/Caspase-3 and changes of ultramicrostructure after 42~C whole body hyperthermia for 30min under general anesthesia with propofol or chloral hydrate in rats.To investigate the mechanism of propofol on changes of neuroethology in WBH and search academic gists for application of different anaesthetic method during WBH and to promote the quality of management of anaesthesia.Methods:1.Grouping and prepare animal model84 healthy adult male Wister rats were randomly divided into 4 groups(21 rats for each group).Some rats were anesthetized with intraperitoneal injection of chloral hydrate(group A),100mg/kg(group B)or 150mg/kg(group C)of propofol,and some others received no anesthetic treatment as control(group D)after trained with place navigation test for 5 days and then warmed up by radiation to keep the rectal temperature at 42℃for 30min.2.Observation of neuroethology changes in each groupPlace navigation test of Morris Water Maze,spatial probe test and open field test were carried out 24 h after WBH intervention while the escape latency,time of crossing the platform,number of crossed squares,upright time and defecation time were recorded.And then open field test was carried out and open field scores were recorded.3.Observation of apoptosis and expression of Bax/Bcl-2 and Caspase-3 Quick frozen sections of hippocampus of 20 rats for each group were made after neuroethology detection.Hippocampal regions was isolated for(1)detection of opoptotic neurons by TUNEL,(2)determination of Bax/Bcl-2 and Caspase-3 protein expression using SABC immuno-histochemical technique.4.Observation of ultrastrcture of hippocampal CA1The brains of one rat for each group were removed to separate hippocampal CA1 after neuroethology detection,and then put into 3%glutaral fixation fluid after washed by PBS.The samples were prepared to ultrathin section for transmission electron microscope after electron stained by lead citrate and uranyl acetate.5.Statistical analysisThe design is completely random design,and SPSS 10.0 analysis was employed. One-way analysis of variance(ANOVA)was used for measurement data.If the variance of each group were of homogeneity,Newman-Keuls test was used,or we used rank-sum test.P-values less than 0.05 were considered to represent statistically significant differences.Result:1.Neuroethology changes in each groupThere was no significant difference in the escape latency during the place navigation test and among the rats of four groups before WBH.The open field scores and escape latencies after WBH were different in 4 groups which orderly decreased as following:Group D＞Group A＞Group B.There was no significant difference in the escape latency between Group B and Group C.2.The number of apoptotic neurons in each groupThe number of apoptotic neurons in hippocampus orderly increased as following: Group D＜Group C＜Group B＜Group A.3.The expression of Bax/Bcl-2 and Caspase-3 in each groupThe expression of Bax and Caspase-3 in hippocampus orderly increased as following:Group D＜Group C＜Group B＜Group A,while the expression of Bcl-2 protein in hippocampus became orderly enhanced as following:Group D＜Group A＜Group B＜Group C. 4.The ultramicrostructure ofhippocampal neurons in each groupThe ultramicrostructure of neurons in hippocampus was normal in Group D.The ultramicrostructure of neurons in hippocampus changed after WBH which were more severe in Group A,including edema of organelle,vacuolization of mitochondria, rarefaction of endocytoplasmic reticulum,incompletion of synaptic membrane and autophagosome.The ultramicrostructure damages in group B was severe than in group C.Conclusion:The mechanism of neuroethological changes in rats caused by WBH for 30min might be related with the neuron apoptosis in hippocampus and changes of ultramicrostructure.The expression of apoptosis promoter and apoptosis neurons of hippocampus in propofol groups was less than that in chloral hydrate group.And large dose propofol group has less expression of apoptosis promoter and apoptosis neurons of hippocampus than small dosage group.So propofol could antagonize the acute cerebral insult caused by WBH and its effect had correlation with dosage in some extent.
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