Lactobacillus paracasei Relieves Constipation by Acting on the Acetic Acid-5-HT-Intestinal Motility Pathway

Constipation is a major health concern worldwide and requires effective and safe treatment options. In this study, we selected ten strains of two species of lactobacilli to identify whether they were effective against constipation induced by loperamide administration in BALB/c mice. Monitoring of constipation-related indicators indicated that Lactobacillus paracasei (L. paracasei) mainly acted on the whole intestinal peristalsis to relieve constipation. Furthermore, through the detection of biological, chemical, mechanical, and immune barriers in mice, it was discovered that L. paracasei changed the relative abundance of bacteria related to the levels of acetic acid and 5-hydroxytryptamine (5-HT) (such as by increasing the relative abundance of Odoribacter and Clostridium, and reducing the relative abundance of Mucispirillum, Ruminococcus, Coprobacillus, and Dorea), increased the concentration of acetic acid in the intestine, which stimulated enterochromaffin cells, promoted 5-HT synthesis in the colon, enhanced intestinal motility, and relieved constipation. In conclusion, this study provides a theoretical foundation for the development of personalized products for the treatment of constipation.