Abstract
Slow transit constipation (STC) is a common type of constipation with a high incidence rate and a large number of patients. We aimed to investigate the therapeutic effects and potential mechanism of paeoniflorin (PAE) on loperamide-induced Sprague Dawley (SD) rat constipation models. Rats with loperamide-induced constipation were orally administered different concentrations of PAE (10, 20, or 40 mg/kg). In vitro, enterochromaffin (EC)-like RIN-14B cells were treated with 20, 40, or 80 μg/ml PAE. We found that PAE treatment significantly improved the symptoms of constipation and increased the intestinal transit rate. Hematoxylin and eosin (H&E) staining showed that PAE alleviated colonic tissue pathological damage. Besides, our results implied that PAE concentration-dependently promoted the content of 5-hydroxytryptamine (5-HT) catalyzed by tryptophan hydroxylase (Tph)-1 in the serum of loperamide-induced rats and in RIN-14B cells. Western blot and immunofluorescence (IF) stain indicated that PAE also promoted the expression of G protein-coupled BA receptor 1 (TGR5), transient receptor potential ankyrin 1 (TRPA1), phospholipase C (PLC)-γ1, and phosphatidylinositol 4,5-bisphosphate (PIP2) in vivo and in vitro. RIN-14B cells were cotreated with a TGR5 inhibitor (SBI-115) to explore the mechanism of PAE in regulating the 5-HT secretion. We observed inhibition of TGR5 reversed the increase of 5-HT secretion induced by PAE in RIN-14B cells. We provided evidence that PAE could promote 5-HT release from EC cells and improve constipation by activating the TRPA1 channel and PLC-γ1/PIP2 signaling. Thus, PAE may provide therapeutic effects for patients with STC.
Highlights
Chronic constipation is a common gastrointestinal complaint characterized by decreased bowel movements or defecation straining, which is considered to affect the quality of life of patients [1]
Macroscopic evidence of watery stool in the colon was dramatically observed in PAE (10, 20, and 40 mg/kg)-treated rats compared with the model group (Figure 1(c))
These results indicated that administration of PAE improved colonic motility and defecation in constipated rats
Summary
Chronic constipation is a common gastrointestinal complaint characterized by decreased bowel movements or defecation straining, which is considered to affect the quality of life of patients [1]. It affects 2%–27% of the general population in Western countries [2] and 4%–6% in China [3] with a higher prevalence in the elderly and women. Evidence-Based Complementary and Alternative Medicine transit constipation (STC) is a common type of chronic constipation caused by abnormalities of colonic motility [5]. STC is mainly manifested as weakened and/or disordered colonic peristalsis and the slow speed of stool pushing forward and emptying. Purgative abuse is often encountered many times and is especially worsened in the occurrence of STC
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