Bifidobacterium animalis subsp. lactis CECT 8145 BPL1^® Laxative Effects in Loperamide-Induced Constipated SD Rats

Background: Constipation is a common gastrointestinal (GI) state for which probiotics have shown promise as a relief. This study examined the laxative effects of the strain Bifidobacterium animalis subsp. lactis CECT 8145 (BPL1^®) in a loperamide-induced rat model of constipation. Methods: Fifty-nine rats were divided into control and loperamide-induced constipation groups. Animals received a 3-day intervention with either placebo or probiotic BPL1^® at two doses: 1.5 × 10⁸ CFU (colony-forming units) (low) and 3 × 10⁹ CFU (high). The study assessed several parameters to determine the probiotic's effect, including: stool and gut characteristics, gastrointestinal transit time (GTT), gene expression and gut microbiome composition. Results: While loperamide significantly decreased stool number, weight and humidity, BPL1^® supplementation effectively restored these parameters, being more pronounced at a high dose. Microbiome analysis showed that BPL1^® at a low dose reduced the abundance of Muribaculaceae and Muribaculum gordoncarteri, associated with constipation. In addition, Muribaculaceae abundance was negatively correlated with stool humidity. Functional microbiome profiling indicated that BPL1^® suppressed pathways related to mucin degradation, vancomycin resistance and isoleucine biosynthesis while promoting L-lactate and pyridoxal-P (vitamin B6) biosynthesis, which may support gut motility and barrier integrity. Conclusions:Bifidobacterium animalis subsp. lactis BPL1^® exhibits potential as a functional probiotic for relieving constipation through improving stool excretion and consistency, inducing taxonomic changes and beneficial functional modulation of the intestinal microbiome. These findings justify further investigation into the mechanisms of BPL1^® as a probiotic for constipation management.