[Comparison of the stress distribution of microtitanium and bioresorbable plates in fixation of mandibulotomy].

PURPOSE: The aim of this study was to compare the stress distribution of microtitanium plate and bioresorbable plates in fixation of mandibulotomy. METHODS: Three dimensional models of different internal fixation systems in mandibular resection were established, and three dimensional finite element analysis was carried out to compare the displacement changes of fracture segments and stress distribution of titanium plates under the same stress conditions. RESULTS: The maximum stress value of titanium plate was 49.8 MPa, and that of absorbable plate was 4.42 MPa. The maximum stress value of titanium plate was far greater than that of absorbable plate. However, all the stresses were less than their yield limits. It can be seen from the relative displacement comparison that when the mini-titanium plate was fixed on the mandible, the maximum displacement value was 0.1 mm; when absorbable plate was used for fixation, the maximum displacement value was 0.2 mm, and the relative displacement of both plates was small. CONCLUSIONS: These results suggest that the stiffness and internal strength of bioabsorbable fixation system are sufficient to support bone healing at the mandible site.

Effect of Electroacupuncture at Zusanli (ST36) on Sepsis Induced by Cecal Ligation Puncture and Its Relevance to Spleen.

BACKGROUND: Acupuncture at Zusanli (ST36), Quchi (LI11), and Tianshu (ST25) is commonly used in septic patients by traditional Chinese physicians. The protective effect of acupuncture at ST36 on the intestinal barrier is associated with Cholinergic Anti-Inflammatory Pathway (CAIP). However, its detailed mechanism and whether acupuncture at LI11 and ST25 have similar effects to ST36 remain unclear. AIM: To explore the effects of electroacupuncture (EA) at ST36, LI11, and ST25 on septic rats and investigate the role of the spleen in the treatment of EA at ST36. METHODS: A septic rat model caused by cecal ligation and puncture (CLP) and a postsplenectomy (SPX) CLP rat model were established. Rats were divided into nine groups depending on different treatments. Serum levels of TNF-α, IL-10, D-lactic acidosis (D-LA), double amine oxidase (DAO), and T-lymphocyte subgroup level in intestinal lymph nodes were compared. RESULTS: EA could not improve the 2-day survival of CLP rats. For CLP rats, EA at ST36 and LI11 significantly decreased the levels of TNF-α, IL-10, DAO, and D-LA in serum and normalized intestinal T-cell immunity. For SPX CLP rats, EA at ST36 failed to reduce serum concentrations of TNF-α, IL-10, and D-LA but increased the values of CD3+CD4+/CD3+CD8+ cells and Treg/Th17 cells. CONCLUSIONS: EA at ST36 and LI11, respectively, could alleviate inflammation reaction, protect the intestinal barrier, and maintain intestinal T-cell function in septic rats. Spleen participated in the protective effect of EA at ST36 in sepsis.

Improved accuracy of hemimandibular reconstructions involving the condyle by utilizing hydroformed reconstruction plates rather than hand-bent stock plates.

BACKGROUND: Computer-aided design/computer-aided manufacturing (CAD/CAM) surgical templates allow precise mandibular reconstructive surgery. However, their clinical accuracy is limited by manual plate bending. Digitally hydroformed plates maintain a digital workstream in virtual planning. METHODS: Twelve patients with Brown's class IIc mandibular defects were randomized into two groups: group I (experimental), the reconstruction plate was digitally hydroformed, and group II (control), surgeries were performed CAD/CAM guided with the reconstruction plate manually prebent. The linear and angular deviations of reconstruction outcomes were compared to surgical simulation in both groups. RESULTS: The mean linear and angular deviations of middle and posterior segments were 2.14 ± 0.79 mm, 3.71 ± 0.95 mm, 8.73° ± 1.91°, and 9.06° ± 0.96° in group I and 4.31 ± 0.78 mm, 6.74 ± 1.40 mm, 16.35° ± 0.72°, and 31.48° ± 3.38° in group II, respectively. Measurements in group I were significantly lower than group II (P < .005). CONCLUSION: Digital hydroforming for plate prebent is a reliable method that helps improving the clinical accuracy of CAD/CAM-guided mandibular reconstruction surgery.

Central 5-hydroxytryptamine (5-HT) mediates colonic motility by hypothalamus oxytocin-colonic oxytocin receptor pathway.

Gut-derived 5-hydroxytryptamine (5-HT) is well known for its role in mediating colonic motility function. However, it is not very clear whether brain-derived 5-HT is involved in the regulation of colonic motility. In this study, we used central 5-HT knockout (KO) mice to investigate whether brain-derived 5-HT mediates colonic motility, and if so, whether it involves oxytocin (OT) production in the hypothalamus and OT receptor in the colon. Colon transit time was prolonged in KO mice. The OT levels in the hypothalamus and serum were decreased significantly in the KO mice compared to wild-type (WT) controls. OT increased colonic smooth muscle contraction in both KO and WT mice, and the effects were blocked by OT receptor antagonist and tetrodotoxin but not by hexamethonium or atropine. Importantly, the OT-induced colonic smooth muscle contraction was decreased significantly in the KO mice relative to WT. The OT receptor expression of colon was detected in colonic myenteric plexus of mice. Central 5-HT is involved in the modulation of colonic motility which may modulate through its regulation of OT synthesis in the hypothalamus. Our results reveal a central 5-HT - hypothalamus OT - colonic OT receptor axis, providing a new target for the treatment of brain-gut dysfunction.

A Systematic Review of Rhubarb (a Traditional Chinese Medicine) Used for the Treatment of Experimental Sepsis.

Sepsis is a global major health problem in great need for more effective therapy. For thousands of years, Rhubarb had been used for various diseases including severe infection. Pharmacological studies and trials reported that Rhubarb may be effective in treating sepsis, but the efficacy and the quality of evidence remain unclear since there is no systematic review on Rhubarb for sepsis. The present study is the first systematic review of Rhubarb used for the treatment of experimental sepsis in both English and Chinese literatures by identifying 27 studies from 7 databases. It showed that Rhubarb might be effective in reducing injuries in gastrointestinal tract, lung, and liver induced by sepsis, and its potential mechanisms might include reducing oxidative stress and inflammation, ameliorating microcirculatory disturbance, and maintaining immune balance. Yet the positive findings should be interpreted with caution due to poor methodological quality. In a word, Rhubarb might be a promising candidate that is worth further clinical and experimental trials for sepsis therapy.

Interleukin-6 (IL-6) mediated the increased contraction of distal colon in streptozotocin-induced diabetes in rats via IL-6 receptor pathway.

Colonic dysmotility occurs in diabetes and blood plasma interleukin (IL)-6 levels are significantly elevated in type 1 diabetes mellitus. The aim of this study was to investigate whether IL-6 and the IL-6 receptor pathway mediates colonic dysfunction in type 1 diabetes mellitus. Male SD rats were treated with a single intraperitoneally injected dose of streptozotocin (STZ), and those displaying sustained high blood glucose were selected as diabetes mellitus models. Longitudinal muscle strips of colon were prepared to monitor colonic contraction in vitro. Contractile responses of strips of colon were recorded following treatment with IL-6 in control animals, and following anti IL-6 antibody treatment in STZ-induced diabetes in rats. Concentration of IL-6 in plasma and colon were determined by ELISA. Expressions of IL-6 α-receptor and IL-6 ß-receptor in colon tissues were determined by immunohistochemistry or Western blot analysis. The non-diabetes rats treated with IL-6 and the untreated diabetes rats showed increased contraction of distal colon, whereas the diabetes rats treated with anti-IL-6 antibody showed decreased contraction of distal colon compared with the untreated diabetes rats. The IL-6 levels of plasma but not colon increased in diabetes rats. The expression of IL-6 α-receptor increased in diabetes rats. These results indicate that diabetes rats show an increase in the contractions of distal colon partly via the IL-6-IL-6 receptor pathway.

Oxytocin decreases colonic motility of cold water stressed rats via oxytocin receptors.

AIM: To investigate whether cold water intake into the stomach affects colonic motility and the involvement of the oxytocin-oxytocin receptor pathway in rats. METHODS: Female Sprague Dawley rats were used and some of them were ovariectomized. The rats were subjected to gastric instillation with cold (0-4 °C, cold group) or room temperature (20-25 °C, control group) saline for 14 consecutive days. Colon transit was determined with a bead inserted into the colon. Colonic longitudinal muscle strips were prepared to investigate the response to oxytocin in vitro. Plasma concentration of oxytocin was detected by ELISA. Oxytocin receptor expression was investigated by Western blot analysis. Immunohistochemistry was used to locate oxytocin receptors. RESULTS: Colon transit was slower in the cold group than in the control group (P < 0.05). Colonic smooth muscle contractile response to oxytocin decreased, and the inhibitory effect of oxytocin on muscle contractility was enhanced by cold water intake (0.69 ± 0.08 vs 0.88 ± 0.16, P < 0.05). Atosiban and tetrodotoxin inhibited the effect of oxytocin on colonic motility. Oxytocin receptors were located in the myenteric plexus, and their expression was up-regulated in the cold group (P < 0.05). Cold water intake increased blood concentration of oxytocin, but this effect was attenuated in ovariectomized rats (286.99 ± 83.72 pg/mL vs 100.56 ± 92.71 pg/mL, P < 0.05). However, in ovariectomized rats, estradiol treatment increased blood oxytocin, and the response of colonic muscle strips to oxytocin was attenuated. CONCLUSION: Cold water intake inhibits colonic motility partially through oxytocin-oxytocin receptor signaling in the myenteric nervous system pathway, which is estrogen dependent.

Beta-arrestin2 is involved in the increase of distal colonic contraction in diabetic rats.

Colonic dysmotility occurs in diabetes and the patients exhibit diarrhea or constipation. The pathogenetic mechanisms underlying colonic dysmotility in diabetic patients remain poorly understood. The effects of ß-arrestin2 on colonic contraction in diabetic rats were investigated for the first time. Male SD rats were treated with a single intraperitoneally injected dose of streptozotocin, and those displaying sustained high blood glucose were selected as diabetes mellitus models. Longitudinal muscle strips of the distal colon were prepared to monitor contraction of the colon in vitro. Expression of ß-arrestin2 was investigated by Western blot analysis. Anti-ß-arrestin2 antibody had no direct effect on the contraction of distal colonic strips in both normal and diabetic rats. Carbachol-induced contractions of distal colonic strips were higher in diabetic rats than in normal rats. Anti-ß-arrestin2 antibody partly blocked carbachol-induced increases of distal colonic strips in diabetic rats. The expression level of ß-arrestin2 protein in the colon was higher in diabetic rats than in normal rats. These results suggest that ß-arrestin2 is involved in the increase of distal colonic contraction in diabetic rats.

Effect of interleukin-6 (IL-6) on the vascular smooth muscle contraction in abdominal aorta of rats with streptozotocin-induced diabetes.

Patients with type 1 diabetes are at a risk of hypertension. However, the mechanisms behind the findings are not completely known. The aim of the present study was to investigate involvement of interleukin-6 (IL-6) on the contraction of abdominal aorta in rats with type 1 diabetes. IL-6 levels in the plasma of rats with streptozotocin (STZ)-induced diabetes were determined by ELISA. The abdominal aorta was dissected free of fat and connective tissues and then cut into spiral rings. The endothelium-denuded strip was vertically suspended in tissue chambers containing 5 ml Krebs solution at 37 degrees C and bubbled continuously with 95% O2-5% CO2. The effects of phenylephrine (Phe) on the contractile responses of abdominal aorta were recorded. The effects of IL-6 and anti-rat IL-6 antibody on the Phe-induced response were also examined. Plasma levels of IL-6 increased time-dependently in rats with STZ-induced diabetes. Phe caused concentration-dependent contraction in aortic rings. Phe-induced contractions were higher in vascular strips of STZ-induced diabetic rats than that of control rats. Pretreatment of vascular strips with IL-6 for 1 h did not cause contraction but enhanced the contraction in response to Phe. Treatment of the vascular strips with an anti-IL-6 antibody for 1 h decreased the Phe-induced contractions. These results suggest that IL-6 causes vascular smooth muscle contraction in abdominal aorta of rats with type 1 diabetes.

Exogenous oxytocin reverses the decrease of colonic smooth muscle contraction in antenatal maternal hypoxia mice via ganglia.

Oxytocin (OT) has been reported to have a potential protective effect on stress-induced functional gastrointestinal disorders. This study determined whether colonic contraction in adults was affected by antenatal maternal hypoxia, and whether OT is involved in antenatal maternal hypoxia induced colonic contraction disorder. Isometric spontaneous contractions were recorded in colonic longitudinal muscle strips in order to investigate colonic contractions and the effects of exogenous OT on the contraction in antenatal maternal hypoxia and control mice. Both high potassium and carbachol-induced contractions of proximal colon but not distal colon were reduced in antenatal maternal hypoxia mice. Exogenous OT decreased the contractions of proximal colonic smooth muscle strips in control mice, while it increased contractions in antenatal maternal hypoxia mice. OT increased the contractions of distal colonic smooth muscle strips in both antenatal maternal hypoxia and control mice. Hexamethonium blocked the OT-induced potentiation of proximal colon but not distal colon in antenatal maternal hypoxia mice. These results suggest that exogenous oxytocin reverses the decrease of proximal colonic smooth muscle contraction in antenatal maternal hypoxia mice via ganglia.

[Effect of Chinese medicine intestine adjusting therapy on patients with respiratory failure caused by acute exacerbation of chronic obstructive pulmonary disease and undergoing noninvasive ventilation].

OBJECTIVE: To observe the effect of Chinese medicine intestine adjusting therapy (IAT) on patients with respiratory failure caused by acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and undergoing noninvasive ventilation, their immune function, ventilation indices and incidence of complication. METHODS: Patients matched with the inclusive criteria were randomized into two groups, 30 in each group. All received bi-level positive airway pressure ventilation and conventional drug therapy, but to patients in the treatment group, IAT was applied additionally by electro-acupuncturing (EA) acupoints Zusanli (ST36), Shangjuxu (ST37), Fenglong (ST40), and Quchi (LI11), also the retention enema with Xuanbai Dachengqi Decoction. The nutritional indicators, including serum total protein (TP), serum albumin (ALB) and hemoglobin (HGB); immune indices, including immuno-globulins (IgG, IgA, IgM), complements, and T-lymphocyte subsets; and the incidence of ventilation complications in the two groups were dynamically observed and compared. RESULTS: After treatment, the nutritional indicators went down in both groups (P < 0.05, P < 0.01), but the lowering in the treatment group were lesser. Moreover, the treatment group showed a higher TP level (P < 0.05) and lower depressive amplitude of ALB (P < 0.01) than those in the control group. Immune indices, excepting IgM, increased significantly in both groups (P < 0.05 or P < 0. 01), but the increments in the treatment group were higher, so significant difference was shown between groups (P < 0.05 or P < 0.01). As for comparison in ventilation complication, the incidence of abdominal distension (which was extensively occurred in the control group), belching and error aspiration in the treatment were significantly fewer (P < 0.05, P < 0.01). Besides, the maximum PS and PEEP, and the mechanical ventilation time were significantly reduced in the treatment group (P < 0.05). CONCLUSION: IAT of Chinese medicine is facilitated to improve the nutritional status of AECOPD patients with respiratory failure undergoing noninvasive ventilation, enhance their immune function, improve the ventilatory efficiency, reduce the duration of mechanical ventilation and the occurrence of complications.

Arecoline excites the contraction of distal colonic smooth muscle strips in rats via the M3 receptor-extracellular Ca2+ influx - Ca2+ store release pathway.

Areca is a Chinese herbal medicine that is widely used for constipation. However the mechanisms of its action are not clear. We investigated the effects of arecoline, the most active component of areca, on the motility of rat distal colonic smooth muscle strips. In longitudinal muscle of distal colon (LMDC) and circular muscle of distal colon (CMDC), arecoline increased the contraction in a dose-dependent manner. Tetrodotoxin (TTX) did not inhibit the effects of arecoline. The contractile response to arecoline was completely antagonized by atropine. 4-Diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) strongly depressed the response to arecoline, but gallamine and methoctramine did not. Nifedipine, 2-aminoethoxydiphenyl borate (2-APB), and Ca2+-free Krebs solution with EGTA partly inhibited the effects of arecoline. The sum of Ca2+-free Krebs solution, EGTA, and 2-APB completely inhibited the effects of arecoline. The results show that arecoline stimulates distal colonic contraction in rats via the muscarinic (M3) receptor - extracellular Ca2+ influx - Ca2+ store release pathway. It is likely that the action of areca in relieving constipation is due to its stimulation of muscle contraction.

Sexual differences of the inhibitory effect of ethanol on gastrointestinal motility: in vivo and in vitro studies.

Female brain is more sensitive to the acute exposure of ethanol. This study aimed to investigate the sexual difference of the ethanol-induced inhibition of gastrointestinal motility. Wistar rats were fasted and allowed drinking water only 12 - 18 h before the experiments. In the in vivo experiments, by using an oral radiochromium motility marker, the liquid gastric emptying and intestinal transit were [corrected] measured 30 min after ethanol treatment. In the in vitro study, strips of stomach and duodenum smooth muscle were suspended in organ baths containing Krebs solution, and their isometric contractions were also examined. Systemic administration of ethanol (2 g/kg, i.p.) significantly inhibited the gastric emptying and intestinal transit, and the effect on female rats turned out to be greater than that on the male rats (P < 0.05). In an in vitro study, ethanol (0.38 x 10(-3) M - 1.34 x 10(-3) M) inhibited the motility of gastric antrum and duodenum in rats of both sexes, but there was no sexual difference in the inhibitory effect of ethanol on muscle strips. We concluded that sexual difference of the ethanol-induced inhibition of gastrointestinal motility was not resulted from the smooth muscle itself.

Oxytocin microinjected into dorsal motor nucleus of the vagus excites gallbladder motility via NMDA receptor-NO-cGMP pathway.

Our recent study indicated that, in the dorsal motor nucleus of the vagus (DMV), the N-methyl-D-aspartic acid (NMDA) receptor-nitric oxide (NO)-cGMP pathway participated in the regulation of gallbladder motility in rabbits. Oxytocin (OT) is involved as a neurotransmitter in autonomic regulation. The aim of the present experiments is to investigate the effect of OT microinjected into DMV on the gallbladder motility and the involvement of NMDA receptor-NO-cGMP pathway. A frog bladder connected with transducer was inserted into the gallbladder to record the gallbladder pressure. Microinjection of OT (10-50 nmol/L, 100 nl) dose dependently increased the strength of gallbladder phasic contraction. The excitatory effect of OT (10 nmol/L, 100 nl) was completely abolished by atosiban (10 mmol/L, 100 nl), the specific OT receptor antagonist, but was not influenced by [deamino-Pen(1), O-Me-Tyr(2),Arg(8)]-vasopressin (10 mmol/L, 100 nl), the V(1) receptor antagonist. Pretreatment of ketamine (10 mmol/L, 100 nl), the NMDA receptor antagonist, suppressed the gallbladder motor response to OT; but pretreatment of 6-Cyaon-7-Nitroquinoxaline-2,3-(1H,4H)-Dione (CNQX; 10 mmol/L, 100 nl), the non-NMDA receptor antagonist, did not affect it. Pretreatment of L-NAME (10 mmol/L, 100 nl), the nitric oxide synthase (NOS) inhibitor, or methyl blue (10 mmol/L, 100 nl), the guanylyl cyclase inhibitor, inhibited the excitatory effect of OT on gallbladder motility. Hence, we deduced that the microinjection of OT into the DMV enhanced the gallbladder motility through binding specific OT receptors and activating the NMDA receptor-NO-cGMP pathway.

Arecoline excites the colonic smooth muscle motility via M3 receptor in rabbits.

Arecoline is an effective component of areca (betel nuts, a Chinese medicine named pinang or binglang). The purpose of this study was to investigate the effect of arecoline on the motility of distal colon in rabbits and its mechanisms involved. Strips of colonic smooth muscle were suspended in organ baths containing Krebs solution, and their isometric contractions were examined. The response of smooth muscle to arecoline in colonic strips was recorded. The effects of atropine, gallamine and 1,1-dimethyl-4-diphenylacetoxypiperidiniumiodide (4-DAMP) on arecoline-induced contraction were also observed. Arecoline (1 nM - 1 microM) produced a concentration-dependent contraction in both the longitudinal and the circular smooth muscle of rabbit colon. Atropine (10 microM) abolished the arecoline (80 nM)--induced contraction. M3 receptor antagonist, 4 - DAMP (0.4 microM), abolished the arecoline (80 nM)--related response, whereas M2 receptor antagonist, gallamine (0.4 microM), did not affect the effect of arecoline. These results suggest that arecoline excites the colonic motility via M3 receptor in rabbits.

Participation of caudal ventrolateral medulla in the regulation of gallbladder motility in rabbits.

To investigate whether the caudal ventrolateral medulla (CVLM) participates in the regulation of gallbladder motility, we studied the effects of microinjection of L-glutamate and other agents into the CVLM on gallbladder pressure (GP) in anesthetized rabbits. A frog bladder connected with a force transducer was inserted into the gallbladder to record the change of GP. Microinjection of L-glutamate into the CVLM decreased GP, While micnoinjection of gamma-amino-butyric acid (GABA) increased GP. Microinjection of ketamine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, into CVLM increased GP, while microinjection of 6-cyano-7-nitroquinoxaline-2,3-(1H,4H)-dione (CNQX), a competitive (+/-)-a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor antagonist, had no significant effect on GP. The effects of L-glutamate was abolished by ketamine, but not by CNQX. Intravenous injection of phentolamine or transection of the spinal cord eliminated the effects of L-glutamate on GP. These results indicate that [1] CVLM participated in the regulation of gallbladder motility; [2] endogenous L-glutamate in CVLM is involved in the regulation mediated by NMDA receptors, the output of which is sent through sympathetic nerve and alpha-adrenergic receptors.

Endogenous oxytocin excites phasic contraction of gallbladder in rabbits through oxytocin receptor.

These experiments were performed to study the effect of oxytocin (OT) and it's specific receptor on gallbladder motility in rabbits. The fasted New Zealand white rabbits (2.0-2.5 kg) were anaesthetized by urethane (1 g/kg). The gallbladder pressure was recorded continuously to monitor the gallbladder motility. Systemic OT (0.01, 0.02, 0.04 mg/kg, iv) did not affect the gallbladder pressure, but dose-dependently increased the frequency of phasic contraction. Five min after OT administration (0.04 mg/kg, iv), the strength of phasic contraction increased to 0.23 +/- 0.08 mmHg/min (P < 0.01, n = 6). The gallbladder motility returned to normal 15 min later after OT treatment. Intravenous injection of atosiban (0.04 mg/kg, iv), an OT receptor antagonist, decreased the strength of gallbladder phasic contraction but did not affect gallbladder pressure. Pretreatment of atosiban (0.04 mg/kg, iv) completely abolished the systemic OT effect on gallbladder. Vasopressin (VP) (0.1 - 0.5 IU/kg, iv) dose-dependently decrease the gallbladder pressure but did not affect the phasic contraction. MK-329 (0.4 mg/kg, iv), the CCK-A receptor antagonist, L-365, 260 (0.4 mg/kg, iv), the CCK-B receptor antagonist and atropine (0.2 mg/kg, iv), the M receptor antagonist, did not affect the OT effect on gallbladder motility. We suggest that endogenous OT regulates gallbladder phasic contraction through specific OT receptor. This effect is independent of the peripheral CCK and M receptors.

Effect of oxytocin on contraction of rabbit proximal colon in vitro.

AIM: To investigate the effects of oxytocin (OT) on isolated rabbit proximal colon and its mechanism. METHODS: Both longitudinal muscle (LM) and circular muscle (CM) were suspended in a tissue chamber containing 5 mL Krebs solution (37 degrees ), bubbled continuously with 950 mL x L(-1) O(2) and 50 mL x L(-1) CO(2). Isometric spontaneous contractile responses to oxytocin or other drugs were recorded in circular and longitudinal muscle strips. RESULTS: OT (0.1 U x L(-1)) failed to elicit significant effects on the contractile activity of proximal colonic smooth muscle strips (P>0.05). OT (1 to 10 U x L(-1)) decreased the mean contractile amplitude and the contractile frequency of CM and LM. Hexamethonium (10 micromol x L(-1)) partly blocked the inhibition of oxytocin (1 U x L(-1)) on the contractile frenquency of CM. N(omega))-nitro-L-arginine-methylester (L-NAME, 1 micromol x L (-1)), progesterone (32 micromol x L(-1)) and estrogen (2.6 micromol x L(-1)) had no effects on OT-induced responses. CONCLUSION: OT inhibits the motility of proximal colon in rabbits. The action is partly relevant with N receptor, but irrelevant with that of NO, progesterone or estrogen.

Effects of progesterone on gastric emptying and intestinal transit in male rats.

AIM: To study the dose-dependent of progesterone (P) effect and the interaction between the oxytocin (OT) and P on gastrointestinal motility. METHODS: In order to monitor the gastric emptying and intestinal transit, the SD male rats were intubated via a catheter with normal saline (3 ml/kg) containing Na(2)(51)CrO(4) (0.5 microCi/ml) and 10% charcoal. OT was dissolved into normal saline and P was dissolved into 75% alcohol. RESULTS: Low does of P (1 mg/kg, i.p.) enhanced the gastric emptying (75+/-3%, P<0.05) and high dose of P (5 mg/kg, i.p.) inhibit it (42+/-11.2%, P<0.01). P (1 mg/kg) increased the intestinal transit (4.2+/-0.3, P<0.05) while the higher dose (10-20 mg/kg) had no effect. OT (0.8 mg/kg, i.p.) inhibited the gastric emptying (23.5+/-9.8%, P<0.01). The inhibitory effects of P(20 mg/kg) (32+/-9.7%, P<0.05) and OT (0.8 mg/kg) on gastric emptying enhanced each other when the two chemicals were administrated simultaneously (17+/-9.4%, P<0.01). CONCLUSION: Low dose of P increased GI motility while high dose of P decreased it. During the later period of pregnancy, elevated plasma level of OT may also participate in the gastrointestinal inhibition.