Agarwood Induced Laxative Effects via Acetylcholine Receptors on Loperamide-Induced Constipation in Mice

Agarwood (Aquilaria sinensis, Aquilaria crasna) is well known as an incense in the oriental region such as Thailand, Taiwan, and Cambodia, and is used as a digestive in traditional medicine. We investigated the laxative effects and mechanism of agarwood leaves extracted with ethanol (EEA-1, Aquilaria sinensis; EEA-2, Aquilaria crasna). EEA-1, EEA-2, the main constituents of EEAs (mangiferin, and genkwanin-5-O-primeveroside), and senna increased the frequency and weight of stools in loperamide-induced constipation model mice. EEA-1 and EEA-2 did not induce diarrhea as a side effect, but senna induced severe diarrhea. EEA-1 and senna increased gastro-intestinal (GI) transit in the model mice. EEA-1, but not senna, also increased the intestinal tension of isolated jejunum and ileum in guinea pigs, and the tension increase was blocked by atropine, a muscarinic receptor antagonist, but not by other inhibitors (granicetron, pyrilamine, or bradykinin-antagonist peptide). Furthermore, the increase in frequency and weight of stools induced by EEA-1 were blocked by pre-administration of atropine in the model mice. These findings indicate that EEAs exerted a laxative effect via acetylcholine receptors in the mouse constipation model.     

Clinical Study of Senna Administration to Nursing Mothers: Assessment of Effects on Infant Bowel Habits

Fifty nursing mothers were given regular doses of a senna compound (Senokot Granules) and 50 received mineral oil or magnesia (Magnolax) to determine whether senna was an effective laxative and whether senna affected the bowel habits of infants of nursing mothers. Senna laxative was effective in 49 of 50 mothers. Infant bowel habits were not affected by senna administration to nursing mothers. The evidence suggests that the active principles of senna if they are transmitted in breast milk have no effect on the evacuation patterns of nursed infants.     

Antifilarial activity of Centratherum anthelminticum seed extracts on Setaria cervi.

Effect of aqueous and alcoholic extract of C. anthelminticum was studied on the spontaneous movements of the whole worm and nerve-muscle preparation of S. cervi. Ethylacetate, acetone and methanol extract showed similar effect, of causing inhibition of spontaneous motility of the nerve-muscle preparation of S. cervi characterized by decreased amplitude and frequency of contractions. The inhibitory effect on the motility was reversible. Further, the extracts did not involve the blockade of cholinergic receptors as evidenced by the presence of unaltered stimulant response of acetylcholine in the presence of drug in bathing fluid.     

Alpha-adrenergic receptor blocking effect of Cleistanthus collinus (Roxb.) Benth. and Hook f. leaf extract on guinea pig isolated smooth muscle preparations

Aqueous extract of C. collinus leaves inhibited norepinephrine induced contraction in guinea pig vas deferens and aortic strip in a dose-dependent manner. Inhibition of acetylcholine induced contraction in ileum was dose independent. C. collinus extract per se had no effect on isolated guinea pig vas deferens and aortic strip, but inhibited norepinephrine induced contraction in a dose-dependent manner probably by its antagonist action on alpha-adrenergic receptor. It had inconsistent effect on guinea pig ileum in vitro preparation.     

Participation of cholinergic pathways in α-hederin-induced contraction of rat isolated stomach strips

The dry extract of Hedra helix leaves and its main active compounds, predominantly α-hederin and hederacoside C, has been traditionally believed to act spasmolytic. However, it has been recently proved that both, the extract of ivy and triterpenoid saponins, exhibit strong contractile effect on rat isolated stomach smooth muscle strips. It turned out that the most potent contractile agent isolated from the extract of ivy leaves is α-hederin. Thus, it seems reasonable to estimate the mechanism of the contractile effect of this saponin. The presented study was aimed at verifying the participation of cholinergic pathways (muscarinic and nicotine receptors) in α-hederin-induced contraction. The experiments were carried out on rat isolated stomach corpus and fundus strips under isotonic conditions. The preparations were preincubated with either atropine or hexamethonium and then exposed to α-hederin. All results are expressed as the percentage of the response to acetylcholine - a reference contractile agent. The obtained results revealed that the pretreatment of isolated stomach strips (corpus and fundus) with atropine neither prevented nor remarkably reduced the reaction of the preparations to α-hederin. Similarly, if the application of saponin was preceded by the administration of hexamethonium, the strength of the contraction of stomach fundus strips induced by α-hederin was not modified. Concluding, it can be assumed that the cholinergic pathways do not participate in α-hederin-evoked contraction of rat isolated stomach preparations.     

No clastogenic activity of a senna extract in the mouse micronucleus assay.

In previous studies, an analytically well-defined senna extract, commonly used as a laxative, gave positive responses in vitro in the Ames test and in the CHO assay. Therefore, the objective of this study was to investigate the genotoxic activity of the same senna extract in an in vivo genotoxicity assay by means of the generally acknowledged MNT. After administration of an oral dose of 2000 mg senna extract/kg to NMRI mice of both genders, which is equivalent to 119 mg potential rhein/kg, 5.74 mg potential aloeemodin/kg and 0. 28 mg potential emodin/kg, there were no elevated levels of micronuclei in bone marrow cells. Kinetic studies were performed in parallel to demonstrate target organ availability. Highest concentrations in the plasma were reached after 1 h with 3.4 microg rhein/ml and 0.065 microg aloeemodin/ml. In all cases, emodin was below the limit of quantification. From the results, the in vitro clastogenic activity of the senna extract could not be confirmed in the mouse micronucleus assay. Together with further negative in vivo genotoxicity studies with anthranoids, the conclusion can be drawn that there is no indication so far demonstrating a genotoxic risk for patients taking senna laxatives.     

弱激光对大鼠胃运动的调节及其作用途径分析

采用成年Ｗｉｓｔａｒ雄性大鼠,应用Ｒａｙｂｏｕｌｄ法测定了弱激光照射足三里穴对大鼠胃运动的调节作用,实验结果为：（１）弱激光照射足三里穴对大鼠胃内压及胃收缩频率均有明显升高作用;（２）腹腔预先注射酚托拉明,部分抑制了弱激光效应;（３）腹腔预先注射心得安,显著地抑制了弱激光的升压及升频作用,并使胃内压及胃收缩频率低于单纯心得安的效应值;（４）腹腔预选注射纳洛酮,部分抑制了弱激光的效应;（５）腹腔预先     

Effects of the methanolic extract of Chrysanthemum trifurcatum (Desf.) Batt. and Trab. on rat duodenal motility

The effect of the methanolic extract of flowers of Chrysanthemum trifurcatum (Desf.) Batt. and Trab. Var. macrocephalum (viv.) Beg. on the rat duodenum smooth muscle motility was examined in vitro. The extract has shown dose-dependent stimulator effects on the amplitude of the spontaneous contractions. With 0.1 g/ml of extract, maximal stimulation was obtained. With that dose, the variation (%) was significantly 1050 +/- 13 (P<0.001) compared with control and represented 80 +/- 5.83% (P<0.001) of the maximum effect of acetylcholine. Atropine (2 microg/ml) reduced by 81 +/- 4% (P<0.05) the spasmogenic effects of C. trifurcatum and by 92 +/- 3% (P<0.05) the acetylcholine effects, while papaverine (2 microg/ml) completely inhibited the spasmogenic effects of extract. With a fixed dose of acetylcholine added (20 microg/ml), the extract increases its effect, but acetylcholine decreases its action. These results suggested that the methanolic extract of C. trifurcatum could stimulate duodenal smooth muscle contractions through muscarinic receptors. Thy explain the respective traditional use of plant in gastrointestinal problems, especially constipation.     

Evaluation of methanolic extract of Ficus platyphylla on gastrointestinal activity

Methanolic extract of Ficus platyphylla was tested on isolated rabbit jejunum, rat duodenum and gastrointestinal motility in mice. The extract showed a biphasic effect on isolated smooth muscle. Lower concentration of extract caused contraction, while higher concentrations produced relaxation. The contractile phase was attenuated by atropine, while relaxant phase attenuated histamine induced contraction of guinea pig ileum. The extract also exhibited a dose-dependent inhibition of gastrointestinal motility. Acute toxicity test in mice established LD50 value (i.p.) of the extract to be 2000 mg/kg. Preliminary phytochemical screening of the extract gave positive test for flavonoids, tannins and saponins.     

Functional mapping of NPY/PYY receptors in rat and human gastro-intestinal tract

Peptide YY (PYY) is involved in the regulation of several gastro-intestinal functions, including motility. The aims of the present study were (i) to characterize the effects of PYY on smooth muscle strips obtained from the different gastro-intestinal segments in rats and in humans and (ii) to realize a map of the Y receptors expression. Contractions of strips were recorded under isometric conditions, using PYY and acetylcholine as control. We observed that PYY induced a contraction of muscle strips from rat proximal colon, but displayed no effect on other gut segments. Using RT-PCR, mRNA encoding the Y1 and Y4 receptors were detected in muscle strips depending on the segment. In humans, the muscle preparations responded to ACh but not to PYY. Moreover, only Y2 receptor mRNA was found in the ileum and the left colon, but not in other segments. Our study shows the heterogeneity in the expression of Y receptors along the gastro-intestinal tract, and reveals great discrepancies between rats and humans both concerning the expression of Y receptor, and the response of smooth muscle strips to PYY.     

Cholecystokinin stimulates neuronal receptors to produce contraction of the canine colon

The motor effects of cholecystokinin 26-33-amide (CCK octapeptide; CCK-OP) and several purported CCK receptor antagonists on canine colonic circular muscle were determined in pentobarbital anesthetized dogs. Intravenous injections of CCK-OP had no effect on colonic motility at doses that contracted the gallbladder, stomach and duodenum. CCK-OP delivered by intraarterial injection to a small segment of the proximal colon produced a dose related increase in colonic motility with one-half maximum response at 12 ng/Kg and maximum response at 50 ng/Kg. The effects of intraarterial injections of several established CCK-receptor antagonists on proximal colonic responses to intraarterial injections of CCK-OP were determined. Proglumide, 10 mg/Kg, did not produce colonic contractions itself, but antagonized CCK-OP-induced responses. Carbobenzyloxy (CBZ)-CCK27-32-amide antagonized CCK-OP-induced colonic responses and also had no effect on basal colonic motility (0.1-1 and 5 micrograms/Kg). Neither compound antagonized acetylcholine- induced colonic responses. Butoxycarbonyl (BOC)-CCK31-33-amide increased basal colonic motility, but did not alter CCK-OP-induced responses at doses of 0.1 and 0.2 mg/Kg. Dibutyryl-cGMP at a dose of 0.1 mg/Kg did not affect basal motility or CCK-OP-induced contractions. At a dose of 1.0 mg/kg it increased basal colonic motility but did not affect CCK-OP-induced contractions. Pentagastrin increased colonic motor activity only at a dose of 5 micrograms/Kg, i.a., a much higher dose than effective doses of CCK-OP. The mechanism of CCK-OP-induced colonic motor effects also was determined. Atropine sulfate, 100 micrograms/Kg, i.v. significantly reduced both intraarterial acetylcholine-and CCK-OP-induced maximum colonic contractions. Tetrodotoxin, at intravenous doses that completely block neuronal activity, did not affect maximum acetylcholine-induced contractions but practically eliminated maximum CCK-OP-induced maximum colonic responses. In conclusion, intraarterial CCK-OP produces circular muscle contraction of the canine proximal colon that is mediated by stimulation of specific CCK receptors which produce the release of acetylcholine from cholinergic enteric neurons. Proglumide and CBZ-CCK27-32-amide are effective CCK receptor antagonists at these colonic neuronal receptors.     

The efficacy of cisapride vs. placebo and diet in patients with chronic constipation

The effects of cisapride (10 mg three times daily) on the stool evacuation characteristics, laxative consumption (symptom diary) and motility pattern (rectoanal manometry) were assessed in patients with chronic idiopathic constipation who fulfilled Rome II criteria. After a 14-day basal period on a diet rich in fiber (phase I), patients were treated with placebo (n = 20) or cisapride (n = 19) (phase II). Anorectal manometry was performed at the end of each phase. The study was controlled, randomized and double blind. Side effects related to the use of cisapride were noted and found to be mild. Cisapride and placebo increased stool frequency from 4 (1-11) to 7 (14-12) (p < 0.001) and from 4 (2-10) to 6 (2-11) (p < 0.05) per week, respectively. Straining was decreased from 69.0% to 39.7% in the cisapride (p < 0.0001) group, and from 79% to 35% (p < 0.0001) in the placebo group. Both cisapride and placebo decreased the feeling of incomplete evacuation from 91.7% to 37.5% (p < 0.0001) and from 82.7% to 39.2% (p < 0.0001), respectively. Cisapride reduced the need of laxatives and showed a tendency to normalize stool consistency but did not influence any other symptom or bowel motility parameter.     

Increase in muscarinic receptors in rat intestine by thyrotropin releasing hormone (TRH)

The effect of Thyrotropin Releasing Hormone (TRH) on the contractile activity elicited by acetylcholine and electric stimulation in the rat ileus terminalis was investigated. TRH did not show any intrinsic contractile activity but, after a 30 minute latency period, the peptide caused a shift to the left of the dose-response curve for both acetylcholine and electric stimulation. The binding of 3H-quinuclidinylbenzilate (3H-QNB) assayed on ileum slices disclosed that the addition of TRH increased the number of muscarinic cholinergic receptors without changes in affinity when incubation was performed at pH 7.8, but no effect TRH was demonstrated at pH 7.4. Therefore, in spite of its neural and direct actions on intestine motor activity, TRH may affect the acetylcholine induced contraction by increasing the number of muscarinic receptors at a specific pH.     

Inhibitory effect of hemicholinium-3 on presynaptic nicotinic acetylcholine receptors located on the terminal region of myenteric motoneurons

Previously we have demonstrated the presence of presynaptic nicotinic acetylcholine receptors on the terminals of myenteric neurons in Auerbach's plexus of guinea-pig ileum. During these studies we observed, that the presence of hemicholinium-3, an inhibitor of the high affinity choline uptake significantly influences the contraction of the longitudinal muscle strip preparation. Our aim was to investigate the neurochemical background of this effect and quantitatively characterize the action of HC-3. We studied the effect of HC-3 on epibatidine- and electrical stimulation-evoked contraction and release of [3H]acetylcholine from the guinea-pig longitudinal muscle strip preparation. We found that in the presence of tetrodotoxin, when the contribution of somatodendritic nicotinic acetylcholine receptors to the response was prevented due to the inhibition of axonal conduction, HC-3 inhibited the epibatidine-evoked contraction and [3H]acetylcholine release in the submicromolar range (IC50 = 897 nM and IC50 = 693 nM, respectively), whereas the electrical stimulation-evoked contraction was not affected by HC-3, and the release of [3H]acetylcholine was apparently enhanced. Our data indicate that HC-3 inhibits the presynaptic nicotinic acetylcholine receptors of myenteric neurons. Since these receptors play an important role in the regulation of cholinergic neurotransmission in the enteric nervous system, the use of HC-3 in [3H]acetylcholine release experiments might bias the interpretation of data.     

Galanin induces contraction of isolated cells from circular muscle layer of pig ileum.

The effects of galanin and its interaction with cholecystokinin and acetylcholine on smooth muscle cells were studied in vitro on isolated cells obtained from pig ileum circular muscle layer. Galanin induced a concentration-dependent cell contraction with a maximal contraction (24.5% decrease in cell length from control) obtained at 1 nM. The concentration of galanin inducing a half-maximal contraction was 3 pM. Tetrodotoxin (10 microM) failed to inhibit cell contraction induced by galanin (1 nM), pentagastrin (10 nM) and acetylcholine (1 microM). Atropine abolished the contraction induced by acetylcholine (1 microM), but had no effect on galanin- and pentagastrin-induced contraction. L 364,718 inhibited the contraction induced by CCK8 but not the galanin-induced contraction. At the uneffective concentration of 10 fM, galanin had a synergistic effect with an uneffective concentration of CCK8 (1 pM). These results suggest that (i) galanin contracts smooth muscle cells from pig ileum by acting on a specific receptor; (ii) galanin and either CCK or acetylcholine may act in a synergistic way to induce cell contraction.     

Monosodium glutamate impairs the contraction of uterine visceral smooth muscle ex vivo of rat through augmentation of acetylcholine and nitric oxide signaling pathways

The aim of the study was to examine the toxic effects of Monosodium glutamate (MSG), an extensively used food additive, on the contraction of uterine visceral smooth muscle (UVSM) in rat and to elucidate the probable neurocrine mechanism involved in it. MSG produced significant potentiation of the force and inhibition of frequency of uterus recorded ex vivo in chronic MSG exposure and in single dose acute experiments. MSG also produced significant potentiation of force of acetylcholine induced contraction and no alterations in atropine induced contraction of uterus. Further, MSG produced significant increase in force and frequency of contraction of neostigmine incubated uterus. We have found significant potentiation of the post pause force of contraction of uterus when MSG was applied in adrenaline incubated uterus. MSG also produced significant decrease in frequency of contraction of sodium nitroprusside incubated uterus; increase in frequency of N-ω-Nitro-l-Arginine Methyl Ester incubated uterus and no significant changes in frequency of contraction of methylene blue incubated uterus. These results indicate that MSG potentiates the force of contraction of UVSM predominantly by augmenting the activity of cholinergic intrinsic efferents and inhibits the frequency of contraction probably by augmenting the activity of nitrergic efferents. In conclusion, MSG potentiates the force and inhibits the frequency of contraction of UVSM, and the MSG induced effect is probably mediated through the augmentation of acetylcholine and nitric oxide signaling pathways.     

In vitro myometrial inhibition by the partitioned aqueous fraction of Anthocleista djalonensis leaves

This study investigated the effect on the uterus of the aqueous fraction of the partitioned methanol crude extract of the leaves of Anthocleista djalonensis (AD) and the possible mechanism of AD activity. AD inhibited the concentration-response curves induced by oxytocin and CaCl2 on the rat uterus in vitro and significantly reduced the EC50 in a concentration-dependent manner (p?< 0.05). A similar effect was observed with salbutamol and verapamil on the concentration-response curves obtained for oxytocin and CaCl2. The inhibitory effect of AD was not attenuated in the presence of propranolol. AD, salbutamol, and verapamil also produced a concentration-dependent relaxation on K+-induced sustained uterine contraction. In Ca2+-free medium, AD and salbutamol similarly inhibited oxytocin-induced contraction, but verapamil failed to produce this effect. The present results suggest that AD, being a mixture of phytochemicals, probably exerts inhibitory activity on in vitro uterine contractions of the nonpregnant, diethylstilboestrol-treated rat by multiple mechanisms that do not involve interaction with β-adrenergic receptors and do not solely depend on inhibition of calcium influx.     

Pharmacological reactivity in cricetus aureus uterus (author's transl)]

The motility of the isolated Cricetus auratus uterus was studied and compared to that of other species. Oxitocyn, epinephrine, norepinephrine, histamine, 5-hydroxy-tryptamine and acetylcholine were used as spasmogen agents. There was not contractil response with epinephrine or nor-epinephrine. Histamine reduced basal tonus. There was contraction with acetylcholine, oxytocin and 5-hydroxy-tryptamine. Cricetus auratus uterus appeared more sensitive when the contraction was registered by the isometric method. No taquifilaxy was produced by 5-hydroxy-tryptamine, as opposed to such effect in rat uterus. The Cricetus auratus uterus has, therefore, shown similar reactivity to that of rat, but different from rabbit and guinea-pig.     

Sperm motility inhibiting activity of a phytosterol from Alstonia macrophylla Wall ex A. DC. leaf extract: a tribal medicine

The role of methanolic extract and n-butanol fraction of A. macrophylla leaves was investigated on the forward motility of goat spermatozoa. The methanol extract (600 micro/g/ml) and one n-butanol fraction (Fraction A; 100 microg/ml) showed marked inhibition of sperm forward motility, tested by microscopic and spectrophotometric methods. Approximately, 50-60% of the spermatozoa lost their motility when treated with 600 microg/ml of methanol extract or 100 microg/ml of Fraction A. The Fraction A at 400 microg/ml concentration showed complete inhibition of sperm forward motility at 0 min. The inhibitory activity increased with the increasing concentrations of the fraction. The motility inhibitory activity of the Fraction A was stable to heat treatment at 100 degrees C for 2 min. The compound showed high inhibitory effect in the pH range 6.7-7.6. Fraction A also showed high efficacy for inhibiting human sperm motility, assessed by the microscopic method. The phytochemical analysis of methanolic extract of A. macrophylla leaves revealed the presence of sterols, triterpene, flavonoid, alkaloid, tannin and reducing sugar, while the Fraction A contains beta-sitosterol, a common phytosterol. The results demonstrate that Fraction A (beta-sitosterol) is a potent inhibitor of sperm motility and thus it has the potential to serve as a vaginal contraceptive.     

Absence of effect of somatostatin on the guinea pig gallbladder

The effect of somatostatin (GH-RIH) on cholecystokinin octapeptide (OP-CCK) or acetylcholine (ACh) induced contraction of the guinea pig gallbladder was evaluated in vitro. GH-RIH failed to inhibit the muscle contraction induced by OP-CCK or ACh. To correlate with the in vitro results, the effect of GH-RIH on OP-CCK induced contraction of the gallbladder was evaluated in the guinea pig in vivo. GH-RIH did not affect the OP-CCK induced contraction of the gallbladder. Our results suggest that GH-RIH does not have direct inhibitory effect on the contraction of the guinea pig gallbladder induced by OP-CCK or ACh.