7,8-Dihydroxyflavone Enhanced Colonic Cholinergic Contraction and Relieved Loperamide-Induced Constipation in Rats



Whether 7,8-dihydroxyflavone (7,8-DHF), a tyrosine kinase receptor B (TrkB) agonist, modulates colonic smooth muscle motility and/or alleviates constipation has not yet been studied.


Here, we aimed to determine how 7,8-DHF influences carbachol (CCh)-stimulated contraction of colonic strips and the in vivo effect of 7,8-DHF on constipation.


Muscle strips were isolated from rat colons for recording contractile tension and performing western blotting. Constipation was induced in rats with loperamide.


Although it specifically activated TrkB, 7,8-DHF applied alone neither activated PLCγ1 in the colonic strips nor induced colonic strip contraction. However, 7,8-DHF enhanced CCh-stimulated PLCγ1 activation and strip contraction. The PLCγ1 antagonist U73122 suppressed both CCh-stimulated and 7,8-DHF-enhanced/CCh-stimulated contraction. While clarifying the underlying mechanism, we revealed that 7,8-DHF augmented muscarinic M3 receptor expression in the colonic strips. The M3-selective antagonist tarafenacin specifically inhibited the 7,8-DHF-enhanced/CCh-stimulated contraction of the colonic strips. Since 7,8-DHF increased Akt phosphorylation, and LY294002 (an antagonist of PI3K upstream of Akt) dramatically inhibited both 7,8-DHF-augmented M3 expression and 7,8-DHF-enhanced/CCh-stimulated contractions, we assumed that 7,8-DHF/TrkB/Akt was associated with the modulation of M3 expression in the colonic strips. ANA-12, a specific TrkB antagonist, not only inhibited TrkB activation by 7,8-DHF but also suppressed 7,8-DHF-enhanced cholinergic contraction, 7,8-DHF/CCh-mediated activation of PLCγ1/Akt, and M3 overexpression in colonic strips. In vivo 7,8-DHF, also by promoting intestinal motility and M3 expression, significantly alleviated loperamide-induced functional constipation in rats.


Our results suggest that 7,8-DHF regulates colonic motility possibly via a TrkB/Akt/M3 pathway and may be applicable for alleviating constipation.

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This study was supported by the National Natural Science Foundation of China (NSFC 31371152 to ZQ, 81500414 to LX, and 81500363 to BW) and the Qingdao University Award for the Excellence of Young Physicians to BH. We would like to thank American Journal Experts (www.aje.com) for English language editing.

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Correspondence to Baoguo He.

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Ma, L., Qu, Z., Xu, L. et al. 7,8-Dihydroxyflavone Enhanced Colonic Cholinergic Contraction and Relieved Loperamide-Induced Constipation in Rats. Dig Dis Sci (2021). https://doi.org/10.1007/s10620-020-06817-y

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  • 7,8-dihydroxyflavone
  • Colonic strip
  • Colonic motility
  • Muscarinic M3 receptor
  • Constipation