Effects of psychological stress on small intestinal bacteria and mucosa in mice

Abstract

Objective To investigate the effects of psychological stress on small intestinal bacteria and mucosa in mice, and to explore the relationship between small intestinal disfunction and small intestinal bacteria and mucosa under psychological stress. Methods 48 mice were randomly divided into psychological stress group and control group. An animal model with psychological stress was established lodging the mice and a hungry cat in separate layers of a two-layer cage. D-xylose levels in plasma were measured for estimating the damage degree of small intestinal mucosa. A section of the proximal small intestine was harvested under sterile condition and processed for quantitation for aerobes (Escherichia coli) and anaerobes (Lactobacilli). The quantitation of bacteria was expressed as log10[colony forming units/g]. Results D-xylose concentrations in plasma in psychological stress mice were significantly higher than those in the control group (3.02±0.85 mmol/L vs 0.94±0.33 mmol/L,P＜0.01).Psychological stress resulted in quantitative alterations in the aerobes (E. coli). There was an increase in the number of E. coli in the proximal small intestinal flora (1.79±0.27 log10(CFU/g) vs 1.32±0.22 log10(CFU/g),P＜0.01), and there was decrease in relative proportion of Lactobacilli and E. coli of stressed mice (0.52±0.56 vs 1.14±1.07,P＜0.05), while there was no significant difference in the anaerobes(Lactobacilli) between the two groups (2.31±0.63 log10(CFU/g) vs 2.41±0.34 log10(CFU/g) P＞0.05). D-xylose concentrations in plasma was significantly and positively correlated with the number of E. coli in the proximal small intestinal flora (r=0.6713,P＜0.05). Conclusion Small intestinal disfunction under psychological stress may be related to dysbacteriosis and the damage of mucosa. Key words: Psychological stress; Small intestinal bacteria; Small intestinal mucosa