Objective To investigate the effects of bloodstream infection with pathogenic bacteria on memory and hippocampal pyramidal cells in mice with Alzheimer s disease(AD).Methods Fifty C57BL/6J male mice were injected subcutaneously with D-galactose solution[200 mg/(kg·d)]on the abdominal wall for 8 weeks to construct AD model.During the modeling period,the general state and body mass of mice were observed weekly.After modeling,mice were divided into normal saline(control)group,Escherichia coli group,Pseudomonas aeruginosa group,Klebsiella pneumoniae group,Staphylococcus aureus group and Candida albicans group.Mice in the control group were injected with normal saline through tail vein.Mice in other groups were injected with low(1.5 x 107 CFU/L),medium(1.5 × 108 CFU/L)and high(1.5 × 109 CFU/L)concentrations of corresponding pathogens through tail vein,and observed for 14 days.Body mass and body temperature of mice in each group were measured at the 1th,2th,and 3th day and the 1th and 2th week after injection,respectively.After the observation,the escape latency,swimming speed and times of crossing the platform were detected by Morris water maze test on the 15th day.The water maze experiment lasted for 6 days.After the experiment,mice in each group were sacrificed,and hippocampal tissues were collected and stained with hematoxylin-eosin(HE)to observe the changes of hippocampal histology.Results The body mass of the mice began to decline at the 8th week,and the mental state of the mice decreased obviously compared with the early stage of modeling.The escape latency of some mice in the pathogenic bacteria infection group was longer than that in the control group(P＜0.05),and the swimming speed of mice in the high concentration Klebsiella pneumoniae group in the water maze experiment on the 5 th day was significantly decreased compared with that in the control group(P＜0.05).No obvious abnormalities were found in the hippocampal CA1 and CA3 nerve cells and cortex of mice in the control group,while a small number of apoptotic cells were found in the hippocampal tissue of mice in the Candida albicans group in the experimental group,and the hippocampal nerve cells were slightly disordered in the Klebsiella pneumoniae group and Staphylococcus aureus group.Conclusion Caudal vein infection from AD patients result in memory loss and morphological changes of hippocampal pyramidal cells in AD mice.
维普
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