Effect of <i>Levilactobacillus brevis</i> KU15159 on Intestinal Function and Bowel Activity in Loperamide-Induced Constipation in Sprague-Dawley Rats

Constipation is one of the most common gastrointestinal disorders, with an increasing prevalence. Lactic acid bacteria are known to improve the colon microenvironment; however, the ameliorative effect of <i>Levilactobacillus brevis</i> KU15159 on constipation has not been examined. This study aimed to investigate the effects of <i>L. brevis</i> KU15159 administration on improving intestinal function and defecation activity in an animal model of loperamide-induced constipation. Six-week-old Sprague-Dawley rats were divided into the normal control, constipation induction (loperamide 4 mg/kg), control drug (loperamide+sodium picosulfate 5 mg/kg), and <i>L. brevis</i> KU15159 (loperamide+<i>L. brevis</i> KU15159 1×10¹⁰ CFU/g) groups with corresponding oral treatment for 2 weeks. Compared with the constipation induction group, the L-KU15159 group exhibited significantly improved fecal indices and intestinal transit time (<i>P</i><0.05) and reduced DNA damage in colon cells and fecal water (<i>P</i><0.05). Analysis of the plasma oxygen radical absorbance capacity and lipid peroxides (conjugated dienes) showed that the L-KU15159 group significantly reduced levels of oxidative stress and lipid peroxides in the blood (<i>P</i><0.05). The activities of intestinal harmful enzymes (β-glucosidase, nitroreductase, and β-glucuronidase) were also significantly inhibited in the L-KU15159 group (<i>P</i><0.05). Therefore, <i>L. brevis</i> KU15159 can be considered a functional food that can improve intestinal function, defecation activity, and constipation through its antioxidant and anti-inflammatory effects.