The concomitant use of an osmotic laxative, magnesium sulphate, and a stimulant laxative, bisacodyl, does not enhance the laxative effect

Morning glory seed keeps laxative effect while retains less subchronic toxicity after being fried

ETHNOPHARMACOLOGICAL RELEVANCE

Morning glory seed (MGS), has been widely used in treating constipation especially towards children. Clinically, people usually take fried MGS (MGSF) in formulas to reduce its side effect. However, the safety of MGSF other than MGS has yet to be explored.

OBJECTIVE

The study aimed to reveal the potential mechanisms of using MGSF instead of MGS basing on chemistry, pharmacodynamics and toxicology.

METHODS

The chemical compositions of the extracts of MGS and MGSF were compared using UPLC-Q-TOF/MS method. Simultaneously, to prove the availability and safety of MGSF, we investigated the laxative effect and subchronic toxicity of MGS and MGSF and addressed the mechanism of laxative effect of them.

RESULTS

In this study, less phenolic acids and more fatty acids were detected in MGSF compared with the compounds in MGS. Moreover, we found that MGS group had stronger laxative effect than MGSF group via downregulating the expression of AQP3 protein. As for subchronic toxicity test, the body weights of MGS group were lower than MGSF group. In serum biochemistry and histopathological examinations, MGS group could cause more serious toxicity in liver, kidney and colon than MGSF group with higher values of BUN, Cr, AST and ALP.

CONCLUSION

Based on the findings in this study, MGSF with varied compounds contents could still keep the laxative effect while retain less subchronic toxicity, which emphasized the necessity of processing and provided an insight into the rational use of MGSF in clinical practice.

Distribution of aquaporins and sodium transporters in the gastrointestinal tract of a desert hare, Lepus yarkandensis

Lepus yarkandensis is a desert hare of the Tarim Basin in western China, and it has strong adaptability to arid environments. Aquaporins (AQPs) are a family of water channel proteins that facilitate transmembrane water transport. Gastrointestinal tract AQPs are involved in fluid absorption in the small intestine and colon. This study aimed to determine the distribution of AQPs and sodium transporters in the gastrointestinal tract of L. yarkandensis and to compare the expression of these proteins with that in Oryctolagus cuniculus. Immunohistochemistry was performed to analyse the cellular distribution of these proteins, and the acquired images were analysed with IpWin32 software. Our results revealed that AQP1 was located in the colonic epithelium, central lacteal cells, fundic gland parietal cells, and capillary endothelial cells; AQP3 was located in the colonic epithelium, small intestinal villus epithelium, gastric pit and fundic gland; AQP4 was located in the fundic gland, small intestinal gland and colonic epithelium; and epithelial sodium channel (ENaC) and Na+-K+-ATPase were located in the epithelial cells, respectively. The higher expression levels of AQP1, AQP3, ENaC and Na+-K+-ATPase in the colon of L. yarkandensis compared to those in O. cuniculus suggested that L. yarkandensis has a higher capacity for faecal dehydration.

Hot-water extract of the branches of Hovenia dulcis Thunb. (Rhamnaceae) ameliorates low-fiber diet-induced constipation in rats

Hovenia dulcis Thunb. (Rhamnaceae), also known as oriental raisin tree, is used in traditional herbal medicine. Its extracts have been reported to show various pharmacological effects such as hepatoprotection, antitumor, antiatopic dermatitis, antilipid peroxidation, anti-steatotic, anti-inflammatory, and antiallergic activities. However, there have been no reports on the effect of H. dulcis extracts in relieving constipation so far. The aim of this study was to investigate the effects of a hot-water extract of the branches of H. dulcis (WEHD) on low-fiber diet-induced constipation in Sprague Dawley rats. The in vivo laxative activity of WEHD was assessed by measuring the intestinal transit of charcoal meal and stool parameters. Furthermore, the in vitro spasmogenic activity of WEHD was evaluated by monitoring the temporal profiles of contraction of rat colon in the absence or presence of WEHD. In addition, constituent profiling was conducted using high-performance liquid chromatography analysis. Pretreatment with WEHD significantly enhanced the intestinal transit of charcoal meal and increased the frequency and weight of stools in rats. In addition, the frequency and amplitude of contractile responses of isolated rat colon were markedly enhanced by WEHD. Two organic phenolic acids, ferulic and vanillic acids, were identified in WEHD, of which vanillic acid exhibited spasmogenic activity. To the best of our knowledge, this is the first study to report the laxative and spasmogenic activities of H. dulcis and its constituents, suggesting that WEHD can serve as a complementary and/or alternative laxative in alleviating chronic constipation.

Aquaporins in the Colon as a New Therapeutic Target in Diarrhea and Constipation

Aquaporins (AQPs) play important roles in the water transport system in the human body. There are currently 13 types of AQP, AQP0 through AQP12, which are expressed in various organs. Many members of the AQP family are expressed in the intestinal tract. AQP3 is predominantly expressed in the colon, ultimately controlling the water transport. Recently, it was clarified that several laxatives exhibit a laxative effect by changing the AQP3 expression level in the colon. In addition, it was revealed that morphine causes severe constipation by increasing the AQP3 expression level in the colon. These findings have shown that AQP3 is one of the most important functional molecules in water transport in the colon. This review will focus on the physiological and pathological roles of AQP3 in the colon, and discuss clinical applications of colon AQP3.

Disimpaction of children with severe constipation in 3-4 days in a suburban clinic using polyethylene glycol with electrolytes and sodium picosulphate

AIM

Constipation is a common cause of admission to hospital for disimpaction, as oral laxatives are often inadequate. High-dose oral laxative protocols are used for complete bowel clearance prior to colonoscopy, but have not been reported for treating faecal impaction. The aim of this study was to assess the effectiveness of a high-dose oral protocol using polyethylene glycol with electrolytes (PEG + E) (Movicol Rx) combined with sodium picosulphate (SP) (Dulcolax SP Rx) in faecal impaction in children presenting to a suburban clinic.

METHODS

Forty-four children presented with acute/chronic faecal impaction were given six to eight sachets of PEG + E were given on day 1, with decreasing doses on subsequent 3 days, while 15-20 SP drops were given on days 2 and 3. Compliance with medication was achieved using a simple method of motivation, with the child drinking the laxatives in a race. On day 4, PEG + E was reduced to one sachet and SP to 10 drops as an ongoing maintenance dose. Defecation, soiling, diet and water intake was monitored daily for 7 days in a diary.

RESULTS

Forty-four children (aged 2-17 years) seen over 8 months were reviewed retrospectively. Children began defecating within 10-12 h reaching a maximum volume of stool/day (four cups) on day 2. All patients were disimpacted successfully and in the week following disimpaction there was no reported faecal soiling or complications.

CONCLUSIONS

A high-dose oral protocol combining PEG + E sachets and SP drops successfully and safely disimpacted a cohort of children with acute/chronic constipation presenting to a suburban continence clinic. This protocol appears to be useful to control faecal disimpaction in an outpatient setting, thereby avoiding hospital admission.

Morphine-Induced Constipation Develops With Increased Aquaporin-3 Expression in the Colon via Increased Serotonin Secretion

Aquaporin-3 (AQP3) is a water channel that is predominantly expressed in the colon, where it plays a critical role in the regulation of fecal water content. This study investigated the role of AQP3 in the colon in morphine-induced constipation. AQP3 expression levels in the colon were analyzed after oral morphine administration to rats. The degree of constipation was analyzed after the combined administration of HgCl(2) (AQP3 inhibitor) or fluoxetine (5-HT reuptake transporter [SERT] inhibitor) and morphine. The mechanism by which morphine increased AQP3 expression was examined in HT-29 cells. AQP3 expression levels in rat colon were increased during morphine-induced constipation. The combination of HgCl(2) and morphine improved morphine-induced constipation. Treatment with morphine in HT-29 cells did not change AQP3 expression. However, 5-HT treatment significantly increased the AQP3 expression level and the nuclear translocation of peroxisome proliferator-activated receptor gamma (PPARγ) 1 h after treatment. Pretreatment with fluoxetine significantly suppressed these increases. Fluoxetine pretreatment suppressed the development of morphine-induced constipation and the associated increase in AQP3 expression in the colon. The results suggest that morphine increases the AQP3 expression level in the colon, which promotes water absorption from the luminal side to the vascular side and causes constipation. This study also showed that morphine-induced 5-HT secreted from the colon was taken into cells by SERT and activated PPARγ, which subsequently increased AQP3 expression levels.

Dietary Supplementation of Magnesium Sulfate during Late Gestation and Lactation Affects the Milk Composition and Immunoglobulin Levels in Sows

This experiment was conducted to investigate the effects of dietary supplementation of magnesium sulfate (MgSO₄) during late gestation and lactation on sow and litter performance, fecal moisture, blood biochemistry parameters, immunoglobulin levels and milk composition in sows. Forty-eight sows (Yorkshire×Landrace, 4th to 5th parity) were randomly allocated to 1 of 4 dietary treatments supplemented with 0, 200, 400, or 600 mg/kg MgSO₄ (n = 12). The experiment started on day 90 of gestation and continued through day 21 of lactation. Blood samples were collected on day 107 of gestation, day 0 (farrowing) and 21 (weaning) of lactation for the analyses of the blood biochemistry parameters and immunoglobulin levels. The colostrum and milk samples were obtained on day 0 and 14 of lactation, respectively. Fecal samples were collected from the sows on day 107 of gestation as well as day 7 and 20 of lactation to determine fecal moisture content. The results showed that the survival percentage of piglets and the litter weight at weaning were decreased linearly (p<0.05) and other parameters of the sow or litter performance were not influenced (p>0.05) by MgSO₄ supplementation. The fecal moisture content of the sows were increased (p<0.05) linearly as dietary MgSO₄ increased on day 7 and 20 of lactation. Supplementation with MgSO₄ increased the plasma magnesium (Mg) level linearly (p<0.05) and had a trend to increase total protein level (p>0.05 and p<0.10). However, an increase in the dietary MgSO₄ level resulted in a linear decrease in the colostrum fat content (p<0.05). Dietary MgSO₄ supplementation enhanced the immunoglobulin G (IgG) level (linear, p<0.05) in plasma on day of farrowing and immunoglobulin A (IgA) level in colostrum (quadratic, p<0.05) and milk (linear, p<0.05) of the sows. These results indicated that supplementation with MgSO₄ during late gestation and lactation may have the potential to prevent sow constipation, but may also result in some negative effects.

[The elucidation of the function and the expression control mechanism of aquaporin-3 in the colon]

Aquaporins (AQPs) are membrane channels that transport water within the human body and are therefore important for the regulation of water homeostasis. However, little is known regarding the details of the physiological role of AQP3, which is predominantly expressed in the colon. Thus, we investigated the role of AQP3 in the colon using laxative agents (magnesium sulfate and bisacodyl). The results suggest that the laxative effect produced by magnesium sulfate, which is classified as an osmotic laxative, is not simply a result of the changes in osmotic pressure but is also associated with the increased expression of AQP3 in the mucosal epithelial cells of the colon. In addition, magnesium sulfate increased colonic AQP3 expression through adenylate cyclase activation, which is caused by an increase in the intracellular Mg(2+) concentration. This effect may trigger CREB phosphorylation through PKA activation and promote AQP3 gene transcription. Meanwhile, bisacodyl, which is classified as a stimulant laxative, decreases the expression level of AQP3 in the mucosal epithelial cells of the colon, resulting in the inhibition of water transfer from the intestinal tract to the vascular side of the epithelium, eventually leading to the development of diarrhea. It was also observed that the direct activation of colon macrophages by bisacodyl increases the secretion of PGE2, which acts as a paracrine factor and decreases AQP3 expression in colon mucosal epithelial cells. Future studies of the enteric AQP3 expression level and water transport may aid in the development of new laxative and antidiarrheal agents that target AQP3.

Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extract

ETHNOPHARMACOLOGICAL RELEVANCE

Aquaporin-3 (AQP3) is expressed in mucosal epithelial cells in the colon and is important for regulating fecal water content. We examined the role of AQP3 in the laxative effect of rhubarb extract.

METHODS

After orally administering rhubarb extract or its major component (sennoside A) to rats, the fecal water content, AQP3 expression and prostaglandin E2 (PGE2) concentrations in the colon were examined. The mechanism by which sennoside A decreases the expression of AQP3 was examined using the human colon cancer HT-29 cells and macrophage-derived Raw264.7 cells.

RESULTS

During diarrhea by rhubarb extract administration, the PGE2 levels in the colon increased while the AQP3 expression significantly decreased. Similar changes were also observed when sennoside A was administered. When sennoside A or its metabolites, rheinanthrone and rhein were added to Raw264.7 cells, a significant increase in the PGE2 concentration was observed only in cells treated with rheinanthrone. Fifteen minutes after adding PGE2 to the HT-29 cells, the AQP3 expression decreased to approximately 40% of the control. When pretreated with indomethacin, sennoside A neither decreased the AQP3 expression nor induced diarrhea.

CONCLUSIONS

Sennoside A may decrease AQP3 expression in the colon to inhibit water transport from the luminal to the vascular side, leading to a laxative effect. The decreases in the levels of AQP3 are caused by rheinanthrone, which is a metabolite of sennoside A, this metabolite activates the macrophages in the colon and increases the secretion of PGE2; PGE2 acts as a paracrine factor and decreases AQP3 expression in colon mucosal epithelial cells.