| Objection: Study the effects of Lactobacillus casei on the intestinal flora,behavior and nervous system of depression rat caused by chronic unpredictable mild stress(CUMS)coupled with social isolation.Method: Animals were divided into five groups randomly after adaptive feed,including normal control group(A),model group(B),positive control group(C),Lactobacillus casei group I and group II(D and E,respectively).Except the normal control group,animals in other groups suffered from CUMS throughout the entire experiment to set up depression rat model.Intervention process by gavage started at the fourth week of modeling and continued four weeks,group D and E were administrated with Lactobacillus casei at the dose of 4×108CFU/kg/d and 8×108CFU /kg/d,respectively,group C was administrated with paroxetine at the dose of 1.8mg/kg/d,A and B groups were administrated with the isodose normal saline.Behavioral experiments,including sucrose consumption,open-field test,24 h food consumption and body weight changes,were carried out to evaluate the changes of behavior.At the end of experiment,after 12 h fasting but not water deprivation,rats were anesthesia,prefrontal cortex was separated at low temperature,cecum was collected and storied at-80?,levels of DA,NE and 5-HT in prefrontal cortex were detected by HPLC-ECD,as well as BDNF,p38 MAPK and p ERK1/2 by waster blotting,Trk B and NR1 by RT-PCR,Enterococcus faecalis,Bifidobacterium,Lactobacillus and Escherichia coli from cecum content were detected by RT-PCR.Results: Under CUMS,rats showed depression like behavior,compared with group A,sucrose preference,moving distance and rate in group B decreased 24.6%,37.6%,23.1%,respectively.While these were reversed after intervention.Sucrose consumption and preference,moving distance and velocity in open-field was elevated significantly in Lactobacillus casei groups compared with model group(P<0.001),sucrose preference in group B decreased by 31.4% vs group A,while group C,D,E increased by 20.5%?15.9%?16.0%,respectively when compared with group B(P<0.05);The moving distance and rate increased in intervention group significantly(P<0.05).As for the rate of body weight increase group B was lower than other groups(P<0.05),no big changes of food consumption were found;Under CUMS,the m RNA expression of Trk B and NR1 decreased significantly,as well as the level of DA,NE and 5-HT(P<0.05).But intervention could improve the phenomenon significantly(P<0.05),BDNF in group D and E increased significantly(vs B,40.9% and 42.9%),DA?NE?5-HT in group D and E increased by15.8%?15.5%?11.2% and 20.5%?19.7%?11.7%,respectively.The expression of p38 MAPK and p ERK1/2 in prefrontal cortex increased significantly(B vs A,122%?65.7% and 147%,respectively)(P<0.05),after intervention,it reduced significantly(vs B,23.2%?24.6%?46.9% and 28.7%?29.7%?46.9%,respectively).Suffering from CUMS,Lactobacillus,Enterococcus faecalis and Escherichia coli in gut increased significantly after intervention,all were increased(P<0.05),while Bifidobacterium had the tendency to decrease,and then to increase follow the intervention,but no significant difference was found.Conclusion: Lactobacillus casei showed the effects of improving the depression-like behavior,regulating the gut flora and nervous system of depression rat,suggesting that it may be a new perspective of depression treatment in clinical. |
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