Effects of Bread Yeast Cell Wall Beta-Glucans on Mice with Loperamide-Induced Constipation

Constipation is a common gastrointestinal disorder characterized by changes in intestinal habits. Increasing evidence indicates that long-term use of irritant laxatives causes serious side effects. Meanwhile, more than 50% of patients are dissatisfied with sense of use of non-prescriptional laxatives. β-glucans are natural polysaccharides widely found in yeast, fungus, and plants, which have been reported to exhibit various pharmacological effects. The aim of this study was to characterize the effect of β-glucans extracted from the bread yeast cell wall on loperamide-induced constipation mice. Forty mice were fed with loperamide (10 mg/kg) to make the constipation model and a diet supplemented with 2.5, 5, and 10 mg/kg β-glucan. We assessed the defecation frequency, intestinal transit function of mice, as well as used high-throughput sequencing to analyze the intestinal microbiota composition and functional biological profiles data. Meanwhile, we detected expression of neurotransmitters including acetylcholinesterase, substance P, and serotonin (5-HT) and expression of tight junction protein (TJP) including zonula occludens-1 and mucin-2 in distal colon to characterize the possible molecular mechanisms. β-glucans significantly enhanced intestinal motility and provided a possibility to regulate the expression of neurotransmitters and TJP in mice. The intestinal microecological portion of the treatment group partially recovered and was closer to the normal group. This study showed that β-glucans can influence the intestinal microbiota and restore microecological balance to regulate the express of neurotransmitters and TJP to recover intestinal epithelial mechanical barrier. We suggested that β-glucans could be used as an active nutritional supplement to protect the damaged intestinal barrier and help patients who have constipation complications and dysbiosis.