Objective To investigate the effects of long-term drinking water supplemented with lipopolysaccharide (LPS) on feeding, energy metabolism and behavior of mice.
Method Totally 48 five-week-old C57/BL mice were randomly divided into eight groups. Different concentrations of LPS were injected intraperitoneally to test food intake. Meanwhile, 24 five-week-old C57/BL mice were randomly divided into three groups including control group without LPS, O128:B12 group (adding 5 μg·mL–1 Escherichia coil O128:B12 LPS to drinking water) and O55:B5 group (adding 5 μg·mL–1 E. coil O55:B5 LPS to drinking water). The experiment period was 12 weeks. Open field test and elevated plus-maze test were used to analyze the movement and anxiety behavior of mice. At the end of experiment, the body composition was tested and samples of fat tissue and brain nucleus were collected for gene expression analysis.
Result Intraperitoneal injection of high dose LPS inhibited food intake of mice. Adding 5 μg·mL–1 LPS from different bacteria to drinking water significantly increased food intake of mice (P<0.05), and upregulatedAgRP mRNA expression in the hypothalamic arcuate nucleus, while POMC mRNA expression was not affected. Drinking LPS significantly reduced feed efficiency, decreased fat deposition, and promoted the expression of UCP-1 and PGC-1ɑ in brown fat. Drinking LPS did not influence mouse anxiety behavior, but significantly promoted the locomotor activity of mice. Drinking LPS also significantly upregulated mRNA expression of c-fosandDRD2 in hippocampus.
Conclusion AddingE. coli LPS to drinking water could improve mouse appetite, promote adipose metabolism of mice and increase locomotor activity of mice, which might be related to the increased activity of dopamine neurons in the hippocampus.
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