OBJECTIVETo investigate regulative effect of electroacupuncture (EA) of different frequencies on derangement of gastric electric rhythm in rabbits.

METHODSDerangement of gastric electric rhythm model was made with injection of erythromycin into ear vein in 40 rabbits, and randomly divided into a model group, a 3 Hz-EA group, a 20 Hz-EA group and a 100 Hz-EA group. They were treated with EA at Zusanli (ST 36) with 3 Hz, 20 Hz and 100 Hz, respectively. PDP and PTP at different periods were detected with IEGG spectrum analyzer.

RESULTSErythromycin could significantly enhance PDP and PTP values in the rabbit (P < 0.001). PDP and PTP values were reduced significantly after EA with 3 Hz, 20 Hz and 100 Hz (P < 0.05), with no significant differences in effect on PDP among them (P > 0.05); therapeutic effect of the EA of 20 Hz on PTP was better than that of 3 Hz (P < 0.05), with no significant difference as compared with the EA of 100 Hz.

CONCLUSIONEA of the 3 frequencies shows significantly different regulative effects on derangement of gastric electric rhythm in rabbits.

Animals ; Electroacupuncture ; Erythromycin ; pharmacology ; Female ; Gastrointestinal Motility ; drug effects ; Male ; Rabbits ; Stomach ; physiology

AIMTo explore the effect of central serotonin (5-hydroxytryptamine, 5-HT) on gastric motility in rabbit and to analysis its mechanism.

METHODSIntracerebroventricular (icv) microinjection of drugs were used. The frequency and the amplitude of contractions of gastric motility were recorded.

RESULTS(1) Injection (icv) of 25 microg 5-HT increased the amplitude of contractions and decreased the frequency of gastric motility. (2) The effects of 5-HT were inhibited by injection (icv) of atropine, but intravenous(iv) injection of atropine could only block the increase effect of 5-HT on intragastric pressure. After injection (icv or iv) of phentolamine or propranolol, the effects of 5-HT on gastric motility were not changed markedly. (3) Microinjection (icv) of naloxone or diphenhydramine inhibited the inhibitory effect of 5-HT on the frequency of gastric contractions, and the diphenhydramine reversed the increase effect of 5-HT on intragastric pressure. (4) Vagotomy abolished the effects of 5-HT completely.

CONCLUSIONThere may be different nerve mechanisms in regulation of central 5-HT on the frequency and amplitude of contractions of gastric motility. The increase effect of 5-HT on intragastric pressure is medicated by the cholinergic system in brain, and histamine may be one of the important element on the effect of 5-HT. The cholinergic fibers in vagus nerve transmit the effect. The inhibitory effect of 5-HT on the frequency of contractions is also medicated by activating the cholinergic system in brain, enkephalin and histamine are also involved, and it is transmitted via noncholinergic and nonadrenergic fibers in vagus nerve.

Animals ; Gastrointestinal Motility ; drug effects ; physiology ; Lateral Ventricles ; Rabbits ; Serotonin ; administration & dosage ; pharmacology

OBJECTIVETo investigate the effect of growth hormone secretagogue(ghrelin) on the contraction and relaxation of small intestinal smooth muscle in rats and its mechanism.

METHODSTwenty-four vagotomized rats were injected intraperitoneally with different concentrations of ghrelin (0, 20, 40, 80 μg/kg). The small intestinal transit were observed. The effect of ghrelin(0.01, 0.1, 0.5, 1.0 μmol/L) on the contraction and relaxation of rat small intestinal smooth muscle strips was observed in vitro in the presence of carbachol(50 nmol/L), the locations of ghrelin receptors(GHS-R1a) on different cells in small intestinal muscle layers were detected by immunofluorescence.

RESULTSWith the increase of concentrations, ghrelin elevated the percentage of small intestinal transit[(25.4±1.0)%, (33.7±1.9)%, (39.3±2.4)%, (44.7±2.1)%] in a dose-dependent manner, and the differences were statistically significant among groups(P<0.05). Ghrelin could also enhance the contraction [(67.0±2.4)%,(149.5±3.3)%, (187.1±4.7)%, (213.5±3.4)%] and relaxation[(35.3±1.1)%, (62.9±3.8)%, (79.6±2.7)%, (94.6±2.2)%] of smooth muscle strips mediated by Cch in a dose-dependent manner, and the differences were statistically significant among groups(P<0.05). Immunofluorescence revealed that ghrelin receptors mainly located on membrane of the nerve cells in the muscle layers, while no receptors were observed on membrane of the smooth muscle cells.

CONCLUSIONGhrelin may enhance the effect of the contraction and relaxation of the rat small intestinal smooth muscle mediated by cholinergic neurotransmitters by activating the nerve cells in the enteric plexus.

Animals ; Gastrointestinal Motility ; Ghrelin ; pharmacology ; Intestine, Small ; drug effects ; physiology ; Male ; Muscle Contraction ; drug effects ; physiology ; Muscle, Smooth ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effects of ghrelin on small intestinal transit and intergigestive gastrointestinal migrating myoelectric complex (MMC) in rats.

METHODSAfter a 24-hour fasting, the rats with or without pretreatment with receptor antagonist (D-Lys3)GHRP-6 were given intravenous injections of ghrelin at different doses to observe the changes in small intestinal transit. The MMCs of the fasting rats were recorded using a multilead physiological recording system, and their changes observed in response to intravenous ghrelin injections, or to ghrelin injection following pretreatment with atropine, phentolamine, propranolol, L-arginine or (D-Lys3)GHRP-6, respectively.

RESULTSGhrelin enhanced the small intestinal transit dose-dependently, and this effect was inhibited by application of ghrelin receptor antagonist. Ghrelin also showed excitatory effect on the MMCs, which was inhibited by atropine, L-arginine or (D-Lys3)GHRP-6, but not by propranolol and phentolamine.

CONCLUSIONGhrelin can promote gastrointestinal motilities, and its excitatory effects rely on the cholinergic pathway in close relation to nitric oxide pathway. Ghrelin receptor is involved in its action in promoting the gastrointestinal motilities.

Animals ; Dose-Response Relationship, Drug ; Female ; Gastrointestinal Motility ; drug effects ; physiology ; Gastrointestinal Transit ; drug effects ; physiology ; Ghrelin ; administration & dosage ; pharmacology ; Injections, Intravenous ; Intestine, Small ; drug effects ; physiology ; Male ; Myoelectric Complex, Migrating ; drug effects ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To explore the effect of ghrelin on the duodenal myoelectrical activity during the feeding state and the fasting state in rats. METHODS: One pair of bipolar silver electrodes were chronically implanted in the duodenal serosa of rats for electromyography. The myoelectrical activity was recorded when ghrelin was injected intravenously into rats during the feeding state or the fasting state. Some rats were pretreated with atropine, phentolamine, propranolol, L-arginine, and (D-Lys3)GHRP-6 respectively to explore the mechanism of ghrelin. RESULTS: Duodenal migrating myoelectrical complex (MMC) could be induced by ghrelin in the feeding state. Ghrelin could shorten the length of duodenal MMC cycle and increase the amplitude and frequency of phase III during the fasting state. The percentage of phase III in the MMC cycle did not change. These effects were inhibited by atropine and L-arginine (D-Lys3)GHRP-6, but not by propranolol and phentolamine. CONCLUSION Ghrelin seems to be closely related to the duodenal motility. The excitatory effect of ghrelin on duodenal MMC might rely on the cholinergic pathway, and have a close relationship with NO. The receptor of ghrelin can regulate its activity.
Animals ; Duodenum ; drug effects ; physiology ; Electromyography ; Female ; Gastrointestinal Motility ; drug effects ; Ghrelin ; pharmacology ; Male ; Muscle, Smooth ; physiology ; Myoelectric Complex, Migrating ; drug effects ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effect of interstitial cells of Cajal (ICC) on contraction of intestinal tract smooth muscle induced by motilin receptor agonist.

METHODSTwo kinds of smooth muscle segments were isolated from the duodenum and colon of rabbit. Both kinds of smooth muscle were divided into two groups: group a (normal ICC group of duodenum); group c (impaired ICC group of duodenum); group b (normal ICC group of colon); group d (impaired ICC group of colon), each group contained 20 segments. The impairment of ICC was induced by selectively destroying ICC in the smooth muscle via treatment with methylene blue plus light. Then the frequency and amplitude of contraction of group a and c, group b and d was compared. Then motilin receptor agonist (ABT-229) was added into the Krebs solution, the frequency and amplitude of smooth muscle contraction before and after adding ABT-229 were recorded and compared.

RESULTSThe electron microscopy demonstrated that ICC in methylene blue plus light group were destroyed; the smooth muscle cells and neuron scattered close to ICC were normal. In group a, the contraction frequency, (17.89 +/- 1.88) times/min, was significantly lower as compared with that measured after ABT-229 was added [(18.76 +/- 1.18) times/min (P > 0.05)]; the amplitude of group a was (343 +/- 28) mg, which was lower as compared with that after adding ABT-229 [(597 +/- 68) mg (P < 0.001)]; in group b, the frequency was (5.89 +/- 1.03) times/min, the amplitude was (724 +/- 85) mg, after ABT-229 was added, the construction frequency increased to (8.45 +/- 0.69) times/min (P < 0.001), and the amplitude was (897 +/- 89) mg (P < 0.05), which was not affected by pretreatment with TTX, however it could be weakened by nifedipine significantly. In group c and d, the rhythmic contraction almost disappeared: in group c the contraction frequency was (1.06 +/- 0.24) times/min, and the amplitude were (50 +/- 10) mg. In group d, the amplitude and frequency significantly decreased as compared with the normal group (P < 0.001), in group c, and d, no significant difference in amplitude and frequency was found between the values measured before and after adding ABT-229 (P > 0.05). After Ach (100 micromol/L) was added, both group c and d could generate contraction.

CONCLUSIONICC may play an important role in the rhythmic contraction of intestinal tract. The promoting effect of motilin receptor agonist on intestinal tract may be mediated by ICC. ICC deficiency may cause functional impairment of gastrointestinal tract motivation. The medication may become ineffective when the number of ICC is reduced to a certain extent or the network of ICC is incomplete.

Animals ; Erythromycin ; analogs & derivatives ; pharmacology ; Female ; Gastrointestinal Motility ; drug effects ; physiology ; Interstitial Cells of Cajal ; physiology ; Male ; Rabbits ; Receptors, Gastrointestinal Hormone ; agonists ; Receptors, Neuropeptide ; agonists

OBJECTIVETo investigate the effect of the expression of ghrelin receptors on the postoperative small intestine dysmotility in rat models.

METHODSThe effect of different concentrations of ghrelin (0, 0.01, 0.1, 0.5, 1.0 μmol/L) on the contraction of smooth muscle strips of rat small intestine in the presence or absence of carbachol was observed in vitro. End-to-side anastomosis was performed in the study group and sham controls were used. The expression of ghrelin receptors(GHS-R1a) in small intestine muscle layers was detected by immunohistochemistry and Western blot.

RESULTSIn vitro, ghrelin enhanced the contraction of smooth muscle strips in the presence of carbachol, and the differences in contraction induced by different concentrations of ghrelin(0.1, 0.5, 1.0 μmol/L) were statistically significant [(223±18)%, (245±22)%, (264±25)%, P<0.01]. Immunohistochemistry study showed that GHS-R1a mainly located in the muscular layer of the bowel wall. The expression of GHS-R1a in the circular and longitudinal muscle was significantly weaker than that in the control group. The expression of ghrelin receptors after surgery was down-regulated in the study group, which was lower than that in the control group(0.51±0.02 vs. 0.71±0.01, P<0.01).

CONCLUSIONDown regulation of ghrelin receptors in small intestine muscle layers may contribute to the occurrence of small intestine dysmotility after intestinal surgery.

Animals ; Down-Regulation ; Gastrointestinal Motility ; drug effects ; physiology ; Ghrelin ; pharmacology ; Intestine, Small ; drug effects ; metabolism ; physiology ; surgery ; Male ; Postoperative Period ; Rats ; Rats, Sprague-Dawley ; Receptors, Ghrelin ; metabolism

The purpose of the present study was to evaluate the prokinetic effects of mosapride with non-invasive assessment of myoelectrical activity in the small intestine and caecum of healthy horses after jejunocaecostomy. Six horses underwent celiotomy and jejunocaecostomy, and were treated with mosapride (treated group) at 1.5 mg/kg per osos once daily for 5 days after surgery. The other six horses did not receive treatment and were used as controls (non-treated group). The electrointestinography (EIG) maximum amplitude was used to measure intestinal motility. Motility significantly decreased following surgery. In the treated group, the EIG maximum amplitude of the small intestine was significantly higher than in the controls from day 6~31 after treatment. These findings clearly indicate that mosapride could overcome the decline of intestinal motility after jejunocaecostomy in normal horses.
Anastomosis, Surgical/veterinary ; Animals ; Benzamides/*pharmacology ; Cecum/*drug effects/physiology ; Electrophysiology ; Female ; Gastrointestinal Agents/*pharmacology ; Gastrointestinal Motility/*drug effects ; Horses/*physiology/surgery ; Intestine, Small/*drug effects/physiology/surgery ; Jejunostomy/veterinary ; Male ; Morpholines/*pharmacology

The present study was to investigate the effects of diltiazem, a ghrelin receptor agonist, on food intake and gastrointestinal functions in rats. Rats were intragastrically administered with diltiazem solution (daily 16 mg/kg, 30 mg/kg or 80 mg/kg, 30 d), and the rats with saline as control. To detect the effects of diltiazem on food intake and body weight, the average daily food intake and body weight were recorded, and the serum metabolic hormones of plasma growth hormone (GH) and neuropeptide Y (NPY) were tested by radioimmunoassay. By means of the spectrophotometer and the modified Mett's method, the effects of diltiazem on rat's gastrointestinal function and pepsin activity were tested, respectively. In addition, the gastric juice's acidity of rats was detected by titration and the secretion amount was calculated. The results showed that the food intake and body weight were maximally promoted by diltiazem at the dose of 30 mg/kg daily (30 d). The average daily food intake and body weight were significantly increased, and the serum concentrations of GH and NPY were also remarkably increased in diltiazem-treated groups compared with those in control group. The results also showed that the gastric emptying rate, gastric acid secretion and the activity of pepsin were significantly increased in diltiazem-treated group compared with those in control group. These results suggest that diltiazem induces enhancement of eating, in the same time, it can also stimulate the gastrointestinal function and regulate growth of rat.
Animals ; Body Weight ; drug effects ; Diltiazem ; pharmacology ; Eating ; drug effects ; Female ; Gastric Emptying ; drug effects ; Gastrointestinal Motility ; drug effects ; Gastrointestinal Tract ; physiology ; Growth Hormone ; blood ; Neuropeptide Y ; blood ; Rats ; Rats, Sprague-Dawley ; Receptors, Ghrelin ; agonists

PURPOSE: Itopride hydrochloride (itopride) inhibits acetylcholinesterase (AChE) and antagonizes dopamine D(2) receptor, and has been used as a gastroprokinetic agent. However, its prokinetic effect on the small bowel or colon has not yet been thoroughly investigated. The aim of this study was to investigate the effects of itopride on motor functions of the ileum and colon in guinea pigs. MATERIALS AND METHODS: The distal ileum was excised and the activity of peristaltic contraction was determined by measuring the amplitude and propagation velocity of peristaltic contraction. The distal colon was removed and connected to the chamber containing Krebs-Henseleit solution (K-H solution). Artificial fecal matter was inserted into the oral side of the lumen, and moved toward the anal side by intraluminal perfusion via peristaltic pump. Colonic transit times were measured by the time required for the artificial feces to move a total length of 10cm with 2-cm intervals. RESULTS: In the ileum, itopride accelerated peristaltic velocity at higher dosage (10(-10)-10(-6)M) whereas neostigmine accelerated it only with a lower dosage (10(-10)-10(-9)M). Dopamine (10(-8)M) decelerated the velocity that was recovered by itopride infusion. Itopride and neostigmine significantly shortened colonic transit at a higher dosage (10(-10)-10(-6)M). Dopamine (10(-8)M) delayed colonic transit time that was also recovered after infusion of itopride. CONCLUSION: Itopride has prokinetic effects on both the ileum and colon, which are regulated through inhibitory effects on AChE and antagonistic effects on dopamine D(2) receptor.
Animals ; Benzamides/*pharmacology ; Benzyl Compounds/*pharmacology ; Cholinesterase Inhibitors/pharmacology ; Colon/*drug effects/physiology ; Dopamine/pharmacology ; Dose-Response Relationship, Drug ; Gastrointestinal Motility/*drug effects ; Guinea Pigs ; Ileum/*drug effects/physiology ; Neostigmine/pharmacology ; Receptors, Dopamine D1/antagonists & inhibitors/physiology