| Objective To survey the effect of choline bitartrate on lipopolysaccharide(LPS)-induced neuroinflammation and cognitive deficits ,subsquently to analyze the potential action mechanism.Methods 1. Seventy two C57BL/6J mice were divided randomly into four groups(n=18):control group(Con group), LPS group, choline intervention group(LPS+CHO group) and choline control group(CHO group). Choline pretreatment at a dosage of 40mg/kg for 3 days was carried out in LPS+CHO group and CHO group( 12am,2pm and 4pm for three times a day).Equivalent saline administration was carried out in Con group and LPS group(the method and time is the same as above). Intralateroventricular microinjection of LPS was applied to establish neuroinflammation in LPS group and LPS+CHO group at 8am on the forth day .The other 2 groups were intralatero ventricularly microinjected with equal amount of aCSF. Choline administration was employed during the whole trial.2. During 3 days of pretreatment, the Morris water maze was used to train the learning and memory capacity of mice.The locomotor activity of mice was measured within 5 minutes by the open field test at 8.am. on the fifth day ,including the times of crossing and standing,and then the spatial exploration ability of mice was determined by Morris water maze.3. 6 hours after establishment of neuroinflammation,6 hippocampi were respectively taken from Con group, LPS group, LPS+CHO group and CHO group.Enzyme linked immunosorbent assay was engaged in detecting the expression levels of IL-1 and TNF- a in hippocampus of mice.4. 24 hours after establishment of neuroinflammation, ionized calcium-binding adapter molecule 1(IBA-1)proteins of hippocampal dentate gyrus of 6 mice in each group was analyzed using immunohistochemistry,and light microscope was utilized to observe IBA-1 labeled positive cells in hippocampal dentate gyrus, then images were taken by confocal imaging system and quantitative counting was analyzed by image analysis software.The rest 6 hippocampi were respectively taken from each group and the expression levels of a7 nicotinic acetylcholine receptor(a7nAchR), p38 Mitogen-activated protein kinase(MAPK) and phosphorylated p38 MAPK were determined using western blot.Result 1. The escape latency of mice was shortened with the increase of training time and training frequency during 3 days of pretreatment(P<0.05). There was no significant difference in the escape latency of each group on the same training day(P>0.05). There was no difference in spontaneous activity of mice 24 hours after intracerebroventricular injection of LPS. There was no statistical difference among the times of crossings and standing(P>0.05).There was no significant difference in the swimming speed among each group(P>0.05).2. Compared with the control group, the LPS group of mice in the water maze space exploration experimental test significantly reduced the number of platform crossings(P<0.05), significantly reduced the percent of moving distance spent in the target quadrant(P<0.05) and significantly reduced the percent of time spent in the target quadrant(P<0.05). Compared with the LPS group, the LPS+CHO group of mice increased the number of platform crossings significantly, significantly increased the percent of moving distance spent in the target quadrant(P<0.05) and partially increased the percent of time spent in the target quadrant, the difference was not statistically significant.3. 6 hours after modeling, the content of IL-1 and TNF-a in hippocampus of LPS group was significantly higher than that of CON group(P<0.05). The content of IL-1 in hippocampus of LPS+CHO group was significantly lower than that of LPS group(P<0.05),TNF-a partially decreased in LPS+CHO group.4. 24 hours after modeling, compared with the control group, IBA-1 proteins significantly increased in the dentate gyrus of mice in LPS group(P<0.05),IBA-1 labeled positive cells in LPS+CHO group were significantly lower than those in LPS group(P<0.05). The expression levels of MAPKp-p38 in LPS group were significantly higher than those in CON group(P<0.05), MAPKp-p38 in LPS+CHO group was significantly lower than that in LPS group(P<0.05), the expression levels of a7nAchR in LPS+CHO group were higher than those in CON group, LPS group and CHO group(P<0.05).Conclusion Choline pretreatment could improve LPS-induced cognitive deficits in mice ,could inhibit the increase of IL-1β and TNF-alevels in hippocampi of mice after LPS exposure. It could also decrease the aggregation of IBA-1 labeled positive cells in dentate gyrus of hippocampus. The protective effect may be achieved by activating a7nAchR and lowering the phosphorylation levels of p38MAPK. |
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