Konjac Oligosaccharide Alleviates Constipation in Mice via 5-HT4R/cAMP/PKA/p-CREB Pathway Activation

Abstract

Background

Konjac oligosaccharide (KOS), which is produced through the degradation of konjac glucomannan via enzymatic, chemical, or physical treatments, has been found to have laxative effects. The current study aimed to elucidate the mechanisms underlying the laxative effect of KOS.

Methods

KOS was administered by gavage to wild-type and 5-hydroxytryptamine 4 receptor (5-HT4R)-knockout C57BL/6 mice subjected to loperamide-induced constipation for four weeks. Following treatment, feces, blood, small intestine, colonic tissue, and intestinal contents were collected. Constipation-related parameters, gastrointestinal hormones, and Ca²⁺ concentrations were evaluated. Histopathological changes were examined via hematoxylin and eosin staining. Immunofluorescence staining, Western blotting, and immunohistochemical staining were performed to detect the 5-HT4R/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway. Isolated smooth muscle cells (SMCs) were treated with KOS and GR113808 (a 5-HT4R antagonist), morphologically observed under an inverted microscope, and identified by α-SMA immunofluorescence staining. Cell viability was assessed via CCK-8 assays. 5-HT4R/cAMP/PKA/p-CREB pathway activity in SMCs was detected via Western blotting.

Results

KOS alleviated loperamide-induced constipation in mice. KOS activated the 5-HT4R/cAMP/PKA/p-CREB pathway in loperamide-induced constipated mice. The protective effect of KOS was significantly diminished in 5-HT4R^−/− mice. KOS promoted the proliferation of SMCs by activating the 5-HT4R/cAMP/PKA/p-CREB signaling pathway.

Conclusion

KOS improves loperamide-induced constipation by activating the 5-HT4R/cAMP/PKA/p-CREB signaling pathway.

Keywords

Functional constipation / Konjac oligosaccharide (KOS) / Gut motility / Loperamide / 5-HT4 receptor / CAMP/PKA signaling / Smooth muscle cells / Colonic motility

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Funding

General Project of Hubei Natural Science Foundation(2022CFB412)

7th batch of national old Chinese medicine experts' academic experience inheritance project([2022] No. 76 Letter on Teaching Chinese Medicine)

Hubei Shizhen Talent Project(Hubei Health Department Letter [2024] No.256)

Wuhan anorectal disease combination of Chinese traditional and western medicine treatment clinical medical research center(Wu Ke [2023] No.123)

RIGHTS & PERMISSIONS

The Author(s), under exclusive licence to the Huazhong University of Science and Technology