Live and Heat-Inactivated Lactiplantibacillus plantarum Ameliorate Loperamide-Induced Constipation in Mice via Modulating Gut Microbiota, Short-Chain Fatty Acids and Gastrointestinal Function

Aims: The effects of two Lactiplantibacillus plantarum strains and their probiotics on loperamide-induced constipation in mice were compared, and the possible mechanisms of the two strains in alleviating constipation were explored. Methods: KM mice were divided into the normal group, model group, positive control group, LTJ53 group, LP11824 group, HK-LTJ53 group and HK-LP11824 group. Loperamide was used to induce constipation in the mice. The study examined changes in defecation time, intestinal propulsion rate, gastric emptying rate, gastrointestinal peptides, colon histology, expression of intestinal barrier function genes, gut microbiota, and short-chain fatty acids (SCFAs). Results: Both live and postbiotic forms of L. plantarum significantly shortened defecation time, improved gastric emptying and intestinal motility, increased the levels of 5-hydroxytryptamine (5-HT), gastrin (GAS) and motilin (MTL), decreased the level of vasoactive intestinal peptide (VIP), restored colon morphology, upregulated the expression of Zonula Occludens-1 (ZO-1), mucin 2 (MUC2) and aryl hydrocarbon receptor (AhR), and downregulated the expression of aquaporin 4 (AQP4). They can also regulate the composition of the gut microbiota and alter the levels of SCFAs. Strain-specific effects were observed: LTJ53 was more effective in improving weight loss and gastric emptying, while LP11824 showed stronger efficacy in promoting small intestinal motility. Conclusions: L. plantarum and its postbiotics can relieve constipation through regulating the intestinal flora, enhancing gastrointestinal motility, adjusting the levels of neurotransmitters, and improving the intestinal barrier function. The specific effects of the two strains can support the selection of function-oriented precise intervention.