Improvement of barrier function and stimulation of colonic epithelial anion secretion by Menoease Pills.

Aim: Menoease Pills (MP), a Chinese medicine-based new formula for postmenopausal women, has been shown to modulate the endocrine and immune systems. The present study investigated the effects of MP and one of its active ingredients, ligustrazine, on epithelial barrier and ion transport function in a human colonic cell line, T84.

Methods: Colonic transepithelial electrophysiological characteristics and colonic anion secretion were studied using the short circuit current (ISC) technique. RT-PCR was used to examine the expression of cytoplasmic proteins associated with the tight junctions, ZO-1 (zonula occludens-1) and ZO-2 (zonula occludens-2).

Results: Pretreatment of T84 cells with MP (15 microg/mL) for 72 h significantly increased basal potential difference, transepithelial resistance and basal ISC. RT-PCR results showed that the expressions of ZO-1 and ZO-2 were significantly increased after MP treatment, consistent with improved epithelial barrier function. Results of acute stimulation showed that apical addition of MP produced a concentration-dependent (10-5,000 microg/mL, EC50 = 293.9 microg/mL) increase in ISC. MP-induced ISC was inhibited by basolateral treatment with bumetanide (100 micromol/L), an inhibitor of the Na+-K+-2Cl- cotransporter, apical addition of Cl- channel blockers, diphenylamine-2, 2'-dicarboxylic acid (1 mmol/L) or glibenclamide (1 mmol/L), but not 4, 4'-diisothiocyanostilbene-2, 2'-disulfonic acid or epithelial Na+ channel blocker, amiloride. The effect of MP on ZO-1 and ZO-2 was mimicked by Ligustrazine and the ligustrazine-induced ISC was also blocked by basolateral application of bumetanide and apical addition of diphenylamine-2, 2'-dicarboxylic acid or glibenclamide, and reduced by a removal of extracellular Cl-.

Conclusion: The results of the present study suggest that MP and lligustrazine may improve epithelial barrier function and exert a stimulatory effect on colonic anion secretion, indicating the potential use of MP and its active ingredients for improvement of GI tract host defense and alleviation of constipation often seen in the elderly.