NCU-04 relieves constipation and the depressive-like behaviors induced by loperamide in mice through the microbiome-gut-brain axis.

Constipation is a prevalent gastrointestinal condition that significantly affects patients' physical and mental well-being, yet current treatments often lack safety and efficacy. Emerging evidence highlights the critical role of the microbiota-gut-brain axis (MBGA) in managing constipation, paving the way for probiotics as an adjuvant treatment to improve constipation symptoms. In this study, we isolated a gut probiotic strain, NCU-04, and investigated its improvement effects on loperamide-induced constipation in mice. We demonstrated that NCU-04 exhibited excellent probiotic properties, including robust growth, strong antibacterial and antioxidant capacities, and a lack of hemolytic activity . The administration of NCU-04 effectively improved the defecation-related indicators such as the fecal water content, time to the first black stool defecation, and intestine transit rate, suggesting enhanced gut immobility in constipated mice. Additionally, NCU-04 significantly reduced colon inflammation induced by loperamide. Further, NCU-04 increased levels of colonic motilin, 5-hydroxytryptamine (5-HT), and c-kit, while decreased that of aquaporin 3, vasoactive intestinal peptide, and peptide YY. Notably, NCU-04 effectively upregulated the expression of 5-HT and its receptor (i.e., 5-HT4R) in the brains of constipated mice. High-throughput sequencing revealed that NCU-04 restored the diversity and composition of the gut microbiota disturbed by loperamide, and significantly increased the relative abundance of and genera in the stool, while decreased that of , , and . Importantly, NCU-04 also effectively improved the depression-like behaviors associated with constipation, possibly through 5-HT mediated MGBA. These results suggest that NCU-04 may offer a promising approach for treating constipation and its related depressive symptoms, supporting its potential as a functional food or adjuvant therapy for human health.