Effect Of Propolis On Cerebral And Intestinal Function Injury In Alcohol-induced Depression Mice

ObjectiveTo investigate the effect and mechanism of propolis on depression-like behavior and impairment of brain-gut function in alcohol-exposed depressed mice.Methods1.Establishment of alcoholic depression model and intervention strategy in mice:Thirty male C57 BL/6J mice（age,10 weeks）were divided randomly into 3 groups with 10 mice in each group after acclimation for one week:control,model,and propolis group.Each mouse was housed individually in a cage.Mice in the model group and the propolis group were given fresh 15%alcohol solution from 8 am to 4 PM from Monday to Thursday,tap water from 4 PM to 8 am the next day,and mice in the control group were given tap water free drinking all day long;All water sources were cut off on Friday and Saturday.Mice in the 3 groups were given tap water for free drinking on Sunday,and the mice in each group ate freely throughout the whole process,and were given intragastric administration at 12:00 every day.Mice in the control group and model group were given0.2ml/soybean oil intragastric administration,and mice in the propolis group were given120mg·kg^-1propolis intragastric administration.Mice in all groups were kept in the feeding room with standard light intensity,which was given light from 8:00 to 16:00every day,and deprived of light from 16:00 to 8:00 the next day.The body weight and food intake of mice were determined weekly.2.Behavioral tests:Depression-like behaviors in mice were assessed using sucrose preference tests,open field test,elevated plus maze and forced swim test.3.The pathological changes of CA3 region of hippocampus,duodenum,jejunum,ileum and colon of mice were observed by Hematoxylin eosin（HE）staining.4.The permeability of jejunum and colon was analyzed by tem immunofluorescence and tracer test.5.The levels of Brain-derived neurotrophic factor（BDNF）,Dopamine（DA）,5-hydroxytryptamine（5-HA）,Lipopolysaccharide（LPS）,Intestinal fatty acid binding protein（FABP2）in serum and levels of cytokines such as Tumor necrosis factor（TNF-α）,Interleukin-6（IL-6）and Interleukin-18（IL-18）in spleen homogenate of mice were determined by Enzyme-Linked immunosorbent assay（ELISA）.6.Western blot was used to detect the protein expression levels of Claudin-1,Occludin,ZO-1,Rho A,AMPK,p-AMPK,LKB and p-LKB in jejunum and colon tissues of mice.Results1.After 10 weeks of alcohol exposure,the food intake and growth rate of mice in the model group were generally lower than those in the control group and the propolis group.In the open field experiment,the total movement distance of the three groups was not significantly different,but the movement time of the model group was significantly shorter than that of the other two groups.In addition,compared with the control group,the sugar water preference of the model group was significantly decreased at 12 h after10 weeks of alcohol binge（P<0.05）;In the elevated cross maze experiment,the time and times of entering the open arm were significantly reduced（P<0.05）;The immobility time increased significantly in forced swimming experiment（P<0.05）.After propolis intervention,the above depression-like behavior was significantly improved compared with the model group.2.Compared with the control group,some nerve cells were damaged in the hippocampal CA3 region of the model group.After propolis intervention,nerve cell injury was improved to a certain extent.The expression serum levels of BDNF and DA in the model group were significantly lower than those in the control group（P<0.05）,and its content in the propolis group was significantly higher than that in the model group（P<0.05）.3.Compared with the control group,mice in the model group showed partial pathological damage of colon and jejunum,and intestinal permeability increased,while propolis treatment reduced pathological damage and permeable leakage of intestinal mucosal barrier induced by alcohol.4.The results of Western blotting showed that propolis supplementation increased the expression of ZO-1,claudin-1 and Occludin protein in jejunum and colon tissues（P<0.05）and up-regulated LKB1/AMPK signaling pathway to repair mucosal damage.5.The levels of LPS,FABP2 in serum and TNF-α,IL-6 and IL-18 in spleen homogenate in model group were significantly higher than those in the control group（P<0.05）,the level of propolis was significantly reduced after propolis intervention.Conclusion1.Alcohol exposure can cause depressive disorder in C57 BL/6J mice,showing typical depression-like behavior and pathophysiological changes.2.Propolis,as an important nutrient,can effectively prevent and relieve depressive disorder symptoms and related pathophysiological damage in alcohol-exposed mice,and the mechanism of action may be related to the improvement of brain-intestinal function of propolis in alcohol-exposed mice.