| ObjectiveTo investigate the effect on the memory of adult rats induced the neonatal meningitis by Group B Streptococcus, and the mechanism of BDNF and NGF in this disease.Methods20 SD rats were randomly divided into control group and infection group and the infection group were injected the streptococcus agalactiae by puncturing cisterna magna. When the infection group neonatal rats survived for 60days after treatment with antibiotikum they took the open-field test and step-down inhibitory avoidance task to be tested the memory. Western Blot evaluated the BDNF and NGF levels of hippocampus and cortex in two group rats.Results1. According to the open-field test score, there was no significant difference of horizontal score and vertical score in comparison between control group and infection group, horizontal score in training period:control,47.9±2.83; infection,45.5±3.5. vertical score:control,20.25±1.72; infection,19.2±1.01. horizontal score in test period:control, 17.4±1.22; infection,16.45±0.89. vertical score:control,7.55±0.89; infection,7.7±0.67 (P>0.05).2. The two group rats in test period had lower behaviors scores than that of them in training period when the comparison of the two groups carried out between in training period and test period, horizontal score of control:training,47.9±2.83; test,17.4±1.22. vertical score:training,20.25±1.72; test,7.55±0.89. horizontal score of infection:training, 45.5±3.5; test,16.45±0.89. vertical score:training,19.2±1.01; test,7.7±0.67 P<0.01).3. The scores of step-down inhibitory avoidance task indicated that in training and test period the latency had no significant difference between the two groups, latency in training period:control,1.75(1.15,3.25); infection,1.75(1.15,3.625). latency in 1.5h test period: control,42.5(34.75,57.25); infection,41(37.75,49.25) (P>0.05).4. When each group compared with itself the latency in 1.5h test period had longer than that in training period and the difference was significant, latency of control:1.5h test, 42.5(34.75,57.25); training,1.75(1.15,3.25); latency of infection:1.5h tes,:41(37.75, 49.25); training:1.75(1.15,3.625) (P<0.01).5. There was significant difference of latency in control group in 24h test period compared with that of the infection group, latency of control:66 (61.25,73.5), latency of infection:34.75(32.75,40) (P<0.01);6. Data of Western Blot indicated that the BDNF protein levels of infection group rats of both hippocampus and cortex performed very lower than that of control group, absorbance ratio of infection BDNF:hippocampus,0.966±0.177; cortex,0.418±0.072. absorbance ratio of control BDNF:hippocampus,1.388±0.123; cortex,0.595±0.122) (P<0.01). About NGF, it just had a significant variation in the hippocampus:infection, 0.805±0.062; control,1.002±0.069 (P<0.01), rather than cortex:infection,0.772±0.054; control,0.769±0.032 (P>0.05).7.Data of Immunohistochemical indicated that the expression is significantly higher than control group in cortex and hippocampus BDNF infection group, and the expression of NGF plays, only the hippocampus expression above infection group, the cortex NGF plays no statistical differences of expression and infection group.ConclusionThe memory performed deficient, of adult rats induced the neonatal meningitis by Group B Streptococcus, and which could be related to the reduction of BDNF and NGF in hippocampus and cortex. |
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