<i>Lactobacillus rhamnosus</i> Strains Relieve Loperamide-Induced Constipation via Different Pathways Independent of Short-Chain Fatty AcidsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked how probiotic Lactobacillus rhamnosus relieves constipation, and whether different strains use different mechanisms. Researchers gave five L. rhamnosus strains to constipated mice. They measured stool water, gut transit, gut hormones, serotonin, neurotrophic factors, fecal short-chain fatty acids, and gut microbiota. Constipation was induced with the anti-diarrheal drug loperamide. The design let the team separate strain-specific effects on each part of the gut. Gut bacteria were profiled by 16S rRNA gene sequencing of the V3-V4 region. Short-chain fatty acids were measured by GC-MS.
Who was studied?
The subjects were 42 male SPF-grade BALB/c mice, 6 weeks old, studied at Jiangnan University in China. This was an animal intervention study, not a human trial. Mice were split into a normal group, an untreated constipation model group, and five groups each given one L. rhamnosus strain (CCFM1068, FFJND15-L2, FHeNJZ7-1, FTJDG11-1, or FZJHZ11-7). Strains were dosed daily by gavage at 5 by 10 to the 9 CFU per mL. Constipation was produced with daily loperamide over 5 days.
What were the most important findings?
All five L. rhamnosus strains shortened the time to first black stool, yet none restored fecal short-chain fatty acids to normal. So the relief did not depend on these acids. Effects were strain-specific. CCFM1068 raised fecal water content, boosted alpha-diversity, cut Verrucomicrobia, and increased Firmicutes. CCFM1068 and FZJHZ11-7 restored serum motilin. Strains diverged on other markers. FHeNJZ7-1 and FFJND15-L2 raised colonic serotonin. FTJDG11-1 raised NT-3, while FHeNJZ7-1 and FZJHZ11-7 raised BDNF. Several strains lowered elevated serum peptide YY.
What are the greatest implications of this study?
The results suggest a single probiotic species can ease constipation through several independent pathways, not just short-chain fatty acids. Different strains acted on gut hormones, neurotransmitters, neurotrophic factors, or microbiota composition. This points toward combining strains with complementary mechanisms for stronger relief. It also offers a screening rationale for choosing probiotic strains. Findings come from a mouse model without an opioid-antagonist control or drug comparison. Human relevance and the exact serotonin pathway remain unproven.