ORIGINAL RESEARCH article
Front. Nutr.
Sec. Nutrition and Microbes
Lactobacillus acidophilus alleviates slow transit constipation by modulating 5-HT 1 pathway and gut microbial composition 2
Provisionally accepted
- 1Shanxi Bethune Hospital, Shanxi Medical University, Taiyuan, China
- 2Shanxi Medical University, Taiyuan, China
- 3Shanxi University, Taiyuan, China
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Slow transit constipation (STC) is a chronic disease characterized by delayed 16 intestinal transit and weakened spontaneous contractions of colonic smooth muscle. 17 Current pharmacological treatments are often associated with adverse effects, 18 highlighting the need for safe and more effective therapeutic strategies. This study 19 investigated the potential role of Lactobacillus acidophilus (L. acidophilus) in 20 regulating intestinal motility and alleviating STC, as well as the underlying 21 mechanism. A humanized mouse model was established by intragastric administration 22 of fecal bacterial suspension from STC patients on alternate days, in order to evaluate 23 the effect of L. acidophilus on constipation. The regulatory effect of L. acidophilus on 24 intestinal motility was evaluated using defecation parameters. Colon histopathology 25 was assessed by hematoxylin-eosin (H&E) staining. Immunohistochemistry (IHC), 26 RT-qPCR, ELISA, and in vitro cell experiments were performed to examine the 27 inflammatory cytokine levels and changes in the 5-hydroxytryptamine (5-HT) 28 signaling pathway. In addition, metagenomic sequencing was used to analyze changes 29 in the intestinal microbial community. The results showed L. acidophilus treatment 30 significantly enhanced intestinal peristalsis and maintained the intestinal barrier by 31 up-regulating Occludin expression and down-regulating inflammatory cytokines, 32 including TNF-α and IL-1β, thereby suppressing inflammatory responses. Both in vivo 33 and in vitro experiments showed that L. acidophilus affected the synthesis and release 34 of 5-HT by regulating the expression of TPH1 and the mechanosensitive ion channel 35 Piezo1. Additionally, L. acidophilus reshaped the intestinal microbial community 36 structure and altered inter-bacterial interaction network, which were closely 37 associated with improved intestinal motility. In conclusion, our current research has 38 revealed the improvement of constipation symptoms by L. acidophilus through the gut 39 microbiota composition, intestinal barrier, and the 5-HT signaling pathway. These 40 findings provide a strong theoretical basis for the development of Lactobacillus 41 acidophilus as a potential therapeutic strategy for the treatment of STC.
Keywords: 5-Hydroxytryptamine, fecal microbiota transplantation, Gutmicrobiota, Lactobacillus acidophilus, slow transit constipation
Received: 25 Dec 2025; Accepted: 16 Feb 2026.
Copyright: © 2026 Fan, Qin, Liu, Abbas, Yang, Cheng and Dong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Xiushan Dong
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