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Cellular mechanisms underlying the laxative effect of flavonol naringenin on rat constipation model.

Yang ZH, Yu HJ, Pan A, Du JY, Ruan YC, Ko WH, Chan HC, Zhou WL - PLoS ONE (2008)

Bottom Line: Naringenin could increase intracellular cAMP content and PKA activity, consisted with that MDL-12330A (N-(Cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride) pretreatment reduced the naringenin-induced I(SC).In addition, significant inhibition of the naringenin-induced I(SC) by quinidine indicated that basolateral K+ channels were involved in maintaining this cAMP-dependent Cl- secretion.Taken together, our data suggest that naringenin could stimulate Cl- secretion in colonic epithelium via a signaling pathway involving cAMP and PKA, hence provide an osmotic force for subsequent colonic fluid secretion by which the laxative effect observed in the rat constipation model.

View Article: PubMed Central - PubMed

Affiliation: The School of Life Science, Sun Yat-sen University, Guangzhou, China.

ABSTRACT

Background & aims: Symptoms of constipation are extremely common, especially in the elderly. The present study aim to identify an efficacious treatment strategy for constipation by evaluating the secretion-promoting and laxative effect of a herbal compound, naringenin, on intestinal epithelial anion secretion and a rat constipation model, respectively.

Methods/principal findings: In isolated rat colonic crypts, mucosal addition of naringenin (100 microM) elicited a concentration-dependent and sustained increase in the short-circuit current (I(SC)), which could be inhibited in Cl- free solution or by bumetanide and DPC (diphenylamine-2-carboxylic acid), but not by DIDS (4, 4'- diisothiocyanatostilbene-2, 2'-disulfonic acid). Naringenin could increase intracellular cAMP content and PKA activity, consisted with that MDL-12330A (N-(Cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride) pretreatment reduced the naringenin-induced I(SC). In addition, significant inhibition of the naringenin-induced I(SC) by quinidine indicated that basolateral K+ channels were involved in maintaining this cAMP-dependent Cl- secretion. Naringenin-evoked whole cell current which exhibited a linear I-V relationship and time-and voltage- independent characteristics was inhibited by DPC, indicating that the cAMP activated Cl- conductance most likely CFTR (cystic fibrosis transmembrane conductance regulator) was involved. In rat constipation model, administration of naringenin restored the level of fecal output, water content and mucus secretion compared to loperamide-administrated group.

Conclusions: Taken together, our data suggest that naringenin could stimulate Cl- secretion in colonic epithelium via a signaling pathway involving cAMP and PKA, hence provide an osmotic force for subsequent colonic fluid secretion by which the laxative effect observed in the rat constipation model. Naringenin appears to be a novel alternative treatment strategy for constipation.

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Effect of different channel blockers and bumetanide on Isc evoked by 100 µM NAR in rat colonic mucosa.(A) Stimulation with NAR on basolateral side resulted in an increase in ISC, which is not abolished by DIDS (100 µM, apical), but by apical (ap) application of DPC (1 mM). (B) The NAR induced Isc increases doesn't change when the tissue was pretreated with amiloride (ENaC blocker, 100 µM), but was abolished by basolateral application of 100 µM bumetanide. (C) Comparison of NAR (100 µM)-induced ISC obtained in control (normal K-H solution), apical Na+-free K-H solution with basal normal K-H solution, Na+-free K-H solution on both sides. (**P<0.001 vs. control). (D) Qunindine (100 µM, bl) inhibited NAR (100 µM, bl) stimulated ISC.
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pone-0003348-g003: Effect of different channel blockers and bumetanide on Isc evoked by 100 µM NAR in rat colonic mucosa.(A) Stimulation with NAR on basolateral side resulted in an increase in ISC, which is not abolished by DIDS (100 µM, apical), but by apical (ap) application of DPC (1 mM). (B) The NAR induced Isc increases doesn't change when the tissue was pretreated with amiloride (ENaC blocker, 100 µM), but was abolished by basolateral application of 100 µM bumetanide. (C) Comparison of NAR (100 µM)-induced ISC obtained in control (normal K-H solution), apical Na+-free K-H solution with basal normal K-H solution, Na+-free K-H solution on both sides. (**P<0.001 vs. control). (D) Qunindine (100 µM, bl) inhibited NAR (100 µM, bl) stimulated ISC.

Mentions: In order to study the ion species involved in mediating the NAR-induced ISC, a series of ion substitution experiments were conducted (Fig. 2), and different Cl− channel blockers were examined (Fig. 3A). The change in ISC was defined as the maximal rise in ISC following NAR stimulation and it was normalized to current change per unit area of the epithelial monolayer (µA/cm2).


Cellular mechanisms underlying the laxative effect of flavonol naringenin on rat constipation model.

Yang ZH, Yu HJ, Pan A, Du JY, Ruan YC, Ko WH, Chan HC, Zhou WL - PLoS ONE (2008)

Effect of different channel blockers and bumetanide on Isc evoked by 100 µM NAR in rat colonic mucosa.(A) Stimulation with NAR on basolateral side resulted in an increase in ISC, which is not abolished by DIDS (100 µM, apical), but by apical (ap) application of DPC (1 mM). (B) The NAR induced Isc increases doesn't change when the tissue was pretreated with amiloride (ENaC blocker, 100 µM), but was abolished by basolateral application of 100 µM bumetanide. (C) Comparison of NAR (100 µM)-induced ISC obtained in control (normal K-H solution), apical Na+-free K-H solution with basal normal K-H solution, Na+-free K-H solution on both sides. (**P<0.001 vs. control). (D) Qunindine (100 µM, bl) inhibited NAR (100 µM, bl) stimulated ISC.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553183&req=5

pone-0003348-g003: Effect of different channel blockers and bumetanide on Isc evoked by 100 µM NAR in rat colonic mucosa.(A) Stimulation with NAR on basolateral side resulted in an increase in ISC, which is not abolished by DIDS (100 µM, apical), but by apical (ap) application of DPC (1 mM). (B) The NAR induced Isc increases doesn't change when the tissue was pretreated with amiloride (ENaC blocker, 100 µM), but was abolished by basolateral application of 100 µM bumetanide. (C) Comparison of NAR (100 µM)-induced ISC obtained in control (normal K-H solution), apical Na+-free K-H solution with basal normal K-H solution, Na+-free K-H solution on both sides. (**P<0.001 vs. control). (D) Qunindine (100 µM, bl) inhibited NAR (100 µM, bl) stimulated ISC.
Mentions: In order to study the ion species involved in mediating the NAR-induced ISC, a series of ion substitution experiments were conducted (Fig. 2), and different Cl− channel blockers were examined (Fig. 3A). The change in ISC was defined as the maximal rise in ISC following NAR stimulation and it was normalized to current change per unit area of the epithelial monolayer (µA/cm2).

Bottom Line: Naringenin could increase intracellular cAMP content and PKA activity, consisted with that MDL-12330A (N-(Cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride) pretreatment reduced the naringenin-induced I(SC).In addition, significant inhibition of the naringenin-induced I(SC) by quinidine indicated that basolateral K+ channels were involved in maintaining this cAMP-dependent Cl- secretion.Taken together, our data suggest that naringenin could stimulate Cl- secretion in colonic epithelium via a signaling pathway involving cAMP and PKA, hence provide an osmotic force for subsequent colonic fluid secretion by which the laxative effect observed in the rat constipation model.

View Article: PubMed Central - PubMed

Affiliation: The School of Life Science, Sun Yat-sen University, Guangzhou, China.

ABSTRACT

Background & aims: Symptoms of constipation are extremely common, especially in the elderly. The present study aim to identify an efficacious treatment strategy for constipation by evaluating the secretion-promoting and laxative effect of a herbal compound, naringenin, on intestinal epithelial anion secretion and a rat constipation model, respectively.

Methods/principal findings: In isolated rat colonic crypts, mucosal addition of naringenin (100 microM) elicited a concentration-dependent and sustained increase in the short-circuit current (I(SC)), which could be inhibited in Cl- free solution or by bumetanide and DPC (diphenylamine-2-carboxylic acid), but not by DIDS (4, 4'- diisothiocyanatostilbene-2, 2'-disulfonic acid). Naringenin could increase intracellular cAMP content and PKA activity, consisted with that MDL-12330A (N-(Cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride) pretreatment reduced the naringenin-induced I(SC). In addition, significant inhibition of the naringenin-induced I(SC) by quinidine indicated that basolateral K+ channels were involved in maintaining this cAMP-dependent Cl- secretion. Naringenin-evoked whole cell current which exhibited a linear I-V relationship and time-and voltage- independent characteristics was inhibited by DPC, indicating that the cAMP activated Cl- conductance most likely CFTR (cystic fibrosis transmembrane conductance regulator) was involved. In rat constipation model, administration of naringenin restored the level of fecal output, water content and mucus secretion compared to loperamide-administrated group.

Conclusions: Taken together, our data suggest that naringenin could stimulate Cl- secretion in colonic epithelium via a signaling pathway involving cAMP and PKA, hence provide an osmotic force for subsequent colonic fluid secretion by which the laxative effect observed in the rat constipation model. Naringenin appears to be a novel alternative treatment strategy for constipation.

Show MeSH
Related in: MedlinePlus