Effects of Dangshen on isolated gastric muscle strips in rats

Effect of Aurantii Fructus Immaturus Flavonoid on the Contraction of Isolated Gastric Smooth Muscle Strips in Rats

This study was designed to investigate the effect of Aurantii fructus immaturus flavonoid (AFIF) on the contraction of isolated gastric smooth muscle in rats and explore its underlying mechanisms. Isolated antral longitudinal smooth muscle strip (ALSMS) and pyloric circular smooth muscle strip (PCSMS) of rats were suspended in tissue chambers. The responses of ALSMS and PCSMS to administration of AFIF were observed. Cyclic guanosine monophosphate (cGMP) and protein kinase G (PKG) levels of PCSMS were measured by ELISA kits. In this study, AFIF showed no significant effect on ALSMS contraction, but it dose-dependently reduced the mean contraction amplitude of PCSMS. When the concentration of AFIF reached 3000 μg/mL, 6000 μg/mL, and 10000 μg/mL, its inhibitory effect on PCSMS contraction was significant. This effect of AFIF was weakened in Ca²⁺-rich environment. And Nω-nitro-L-arginine methyl (L-NAME), the inhibitor of nitric oxide synthase (NOS), significantly inhibited AFIF's action in comparison with control (P < 0.05). After incubation with AFIF for 30 min, levels of cGMP and PKG in PCSMS were significantly increased compared with control (P < 0.05). Our results suggest that AFIF has a dose-dependent diastolic effect on PCSMS in rats, which may be related to the regulatory pathway of NO/cGMP/PKG/Ca²⁺.

Dangshen (Codonopsis pilosula) activates IGF-I and FGF-2 pathways to induce proliferation and migration effects in RSC96 Schwann cells

This study evaluates the proliferative and migrative effects of dangshen on RSC96, Schwann cells. We investigated the molecular signaling pathways, which include: (1) survival signaling, IGFs-IGFIR-Akt-Bcl2 and proliferative signaling, cell cycle factors and MAPK pathways. (2) migrate and anti-scar signaling, FGF-2-uPA-MMPs. After treatment with different concentrations (20 microg/ml, 40 microg/ml, 60 microg/ml, 80 microg/ml, and 100 microg/ml) of dangshen. We observed a dose dependent proliferative effect using PCNA Western blotting assay, MTT assay and the wound healing test. We also found that dangshen stimulates the protein expressions of IGF-I pathway regulators, cell cycle controlling proteins and excites the MAPK signaling pathway regulators ERK and P38. Dangshen even stimulates the FGF-2-uPA-MMP 9 migration pathway in RSC 96 Schwann cells. Using MAPK chemical inhibitors, U0126, SB203580, and SP600125, the proliferative effects of dangshen on RSC 96 cells were identified to be ERK- and P38- dependent. Based on these results, applying an appropriate dose of dangshen with biomedical materials would be a potential approach for enhancing neuron regeneration.

Development and application of a capillary electrophoretic method for the composition analysis of a typical heteropolysaccharide from Codonopsis pilosula NANNF

A simple capillary electrophoretic method based on 1-phenyl-3-methyl-5-pyrazolon (PMP) derivatization has been developed for simultaneous separation and determination of nine aldoses (xylose, arabinose, glucose, rhamnose, fucose, galactose, mannose, glucuronic acid and galacturonic acid). The separation of PMP-labeled monosaccharide derivatives was carried out in uncoated capillary (48.5 cm x 75 microm i.d.) and under the selected optimum conditions of pH 11.0, 200 mM borate buffer at applied voltage 15 kV and capillary temperature 20 degrees C, the nine PMP-monosaccharides could be perfectly separated from each other within 40 min. Furthermore, the developed method was firstly applied to determine the sugar composition in the polysaccharide isolated from Chinese Codonopsis pilosula. The results showed that C. pilosula polysaccharide was a typically acidic heteropolysaccharide and was composed of arabinose, glucose, rhamnose, galactose, mannose, glucuronic acid and galacturonic acid in the molar contents of 48.1, 103.5, 16.1, 48.5, 7.5, 4.2 and 119.1 microM, respectively. The assay results were satisfactory.

Significance of changes of gastrointestinal peptides in blood and ileum of experimental spleen deficiency rats

AIM: To explore the mechanism of spleen deficiency (SD) by studying the relationship of gastro-intestinal peptides level and ileal electro-mechanical activity of SD rats and cold restrain rats.

METHODS: (1) spleen deficiency (SD) model was established by feeding Houpou:Zhishi: Dahuang in the ratio of 3:3:2, 3 ml/time, for 42 days. (2) The cold restrain stress model: Animals were restrained on grille and placed in a cool water at 18 °C for 3 h. (3) Substance P (SP) and vasoactive intestinal peptide (VIP) levels in all layers of initial part of ileum and blood in rats were measured by radioimmunoassays (RIA) while changes of electric activity and motility in ileum of rats were recorded with electrode and strain gauge.

RESULTS: SP levels in ileum and blood of experimental SD rats were significantly higher than that of the control groups (9.89 ± 5.65 vs 1.22 ± 1.18, P < 0.005, in ileum; 22.7 ± 3.95 vs 6.60 ± 1.47, P < 0.001, in blood) while the VIP levels of the SD rats were significantly lower than that of the controls (3.50 ± 2.01 vs 9.10 ± 4.91, P < 0.05, in ileum; 229.8 ± 62.4 vs 560.4 ± 151.3, P < 0.001, in blood). As compared with the controls, the average frequency of slow electric waves (21.3 ± 0.96 vs 18.2 ± 2.28, P < 0.05) and motility (21.5 ± 0.58 vs 18 ± 2.65, P < 0.005) of SD rats increased obviously and the frequency of fast waves of SD rat also increased. In spontaneous recovery cases, SP levels recovered significantly (compared with the SD groups, 2.99 ± 0.62 vs 9.89 ± 5.65, P < 0.001, in ileum; 14.4 ± 4.22 vs 22.7 ± 3.95, P < 0.001, in blood) but did not drop to normal. After the SD rats treated with Chinese herbs (Jiawei Sijun zi Tang), SP improved (compared with SD cases, 2.20 ± 1.25 vs 9.89 ± 5.65, (P < 0.001), in ileum; 10.7 ± 1.88 vs 22.7 ± 3.95, (P < 0.001), in blood) and VIP in blood also improved (compared with SD rats, 485.7 ± 229.0 vs 229.8 ± 62.4, P < 0.01) while the amplitude of motility decreased apparently (compared with the SD rats, 0.64 ± 0.096 vs 0.89 ± 0.15, P < 0.01). The ileal SP levels of cool stress didn’t change while the ileal VIP levels of cool stress became significantly lower than that of the control groups (2.87 ± 0.87 vs 9.10 ± 4.91, P < 0.01). The blood SP levels of cool stress were significantly higher (15.60 ± 1.83 vs 6.60 ± 1.47, P < 0.001) whereas the blood VIP levels of cool stress were significantly lower than that of the control group (153.4 ± 70.46 vs 560.4 ± 151.30, P < 0.001).

CONCLUSION: Changes of SP and VIP levels in initial part of ileum and blood of SD rats and cool stress rats may be closely related to the gastrointestinal motility disorders presented in SD and cool stress rats. the Chinese herbs (Jiawei Sijun zi Tang) currently used have partially therapeutic effect.

Effect of pinaverium bromide on stress-induced colonic smooth muscle contractility disorder in rats

AIM: To investigate the effect of pinaverium bromide, a L-type calcium channel blocker with selectivity for the gastrointestinal tract on contractile activity of colonic circular smooth muscle in normal or cold-restraint stressed rats and its possible mechanism.

METHODS: Cold-restraint stress was conducted on rats to increase fecal pellets output. Each isolated colonic circular muscle strip was suspended in a tissue chamber containing warm oxygenated Tyrode-Ringer solution. The contractile response to ACh or KCl was measured isometrically on ink-writing recorder. Incubated muscle in different concentrations of pinaverium and the effects of pinaverium were investigated on ACh or KCl-induced contraction. Colon smooth muscle cells were cultured from rats and [Ca²⁺]_i was measured in cell suspension using the Ca²⁺ fluorescent dye fura-2/AM.

RESULTS: During stress, rats fecal pellet output increased 61% (P < 0.01). Stimulated with ACh or KCl, the muscle contractility was higher in stress than that in control. Pinaverium inhibited the increment of [Ca²⁺]_i and the muscle contraction in response to ACh or KCl in a dose dependent manner. A significant inhibition of pinaverium to ACh or KCl induced [Ca²⁺]_i increment was observed at 10^-6 mol/L. The IC₅₀ values for inhibition of ACh induced contraction for the stress and control group were 1.66 × 10^-6 mol/L and 0.91 × 10^-6 mol/L, respectively. The IC₅₀ values for inhibition of KCl induced contraction for the stress and control group were 8.13 × 10^-7 mol/L and 3.80 × 10^-7 mol/L, respectively.

CONCLUSION: Increase in [Ca²⁺]_i of smooth muscle cells is directly related to the generation of contraction force in colon. L-type Ca²⁺ channels represent the main route of Ca²⁺ entry. Pinaverium inhibits the calcium influx through L-type channels; decreases the contractile response to many kinds of agonists and regulates the stress-induced colon hypermotility.

Morphological properties and residual strain along the small intestine in rats

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine (n = 11).

METHODS: To approach the no-load state, the intestine was surgically excised, transferred to an organ bath and cut transversely into short ring-shaped segments. Each ring was cut radially for obtaining the zero-stress state. The residual stress can be characterised by an opening angle. The strain difference between the zero-stress state and the no-load state is called residual strain.

RESULTS: Large morphometric variations were found along the small intestine. The wall thickness was highest in the proximal duodenum and decreased in distal direction along the axis of the small intestine (P < 0.001). The circumferential length of the inner and outer surfaces decreased rapidly along the length of duodenum by 30%-50% (P < 0.001). The wall area and lumen area showed a similar pattern (P < 0.001). In zero-stress state the rings always opened up after making the cut. The experiments resulted in larger inner circumferential length and smaller outer circumferential length when compared to the no-load state. The wall thickness and wall area did not differ between the no-load and zero-stress state. The opening angle and tangent rotation angle increased along the length of the duodenum and had its highest value 30% down the intestine. Further down the intestine it decreased again (P < 0.001). The serosal residual strain was tensile with the highest value close to the ligament of Treitz (P < 0.001). The mucosal residual strain was compressive in all segments of the small intestine with average values between -0.25 and -0.4 and with the lowest values close to the ligament of Treitz (P < 0.001).

CONCLUSION: Axial variation in morphometric properties and residual strains were found in the small intestine. Existence of large residual strains indicates that the zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.

Screening and identification of proteins mediating senna induced gastrointestinal motility enhancement in mouse colon

AIM: To isolate the proteins involved in pharmacologic action of senna extract (SE) from mouse gastrointestinal tract and to explore the molecular mechanism of gastrointestinal motility change induced by SE.

METHODS: SE was administrated to mice by different routes. Gastrointestinal motility of mice was observed using cathartic, gastrointestinal propellant movement experiments and X-ray analysis. Mouse model for gastrointestinal motility enhancement was established through continuous gastric administration of SE at progressively increased dose. At 3 h and week 3, 4, 6 and 10, morphological changes of gastrointestinal tissues were found under light microscope. Ultrastructural changes of intestinal and colonic tissues at week 6 were observed under transmission electron microscope. The colonic proteomic changes in model mice were examined by two-dimension polyacrylamide gel electrophoresis with immobilized pH gradient isoelectric focusing to screen the differentially expressed proteins, and their molecular masses and isoelectric points were determined. Two N-terminal sequences of the samples were also determined by mass spectrometry.

RESULTS: SE (0.3 g) caused diarrhea after gastric administration in 1-6 h and enhanced gastrointestinal propellant (65.1% ± 7.5%; 45.8% ± 14.6%,P < 0.01) in mice, but intramuscular and hypodermic injection had no cathartic effect. X-ray analysis of gastrointestinal motility demonstrated that gastric administration of SE enhanced gastric evacuation and gastrointestinal transferring function. At 3 h and week 3 and 4 after gastric administration of SE, light microscopic examination revealed no apparent change in gastrointestinal mucosal tissues, but transmission electron microscopic examination revealed inflammatory changes in whole layer of intestinal and colonic wall. Twenty differential proteins were detected in the colonic tissues of the model mice by two-dimensional electrophoresis, and the N-terminal amino acid sequences of two proteins were determined.

CONCLUSION: SE causes diarrhea and enhances gastrointestinal motility through digestive tract administration. Long-term gastric administration of SE induces inflammatory changes and cell damage in the whole gastrointestinal tract. The differential proteins screened from the colonic tissues of the model mice might mediate the enhancing effect of SE on gastrointestinal motility.

Direct effect of croton oil on intestinal epithelial cells and colonic smooth muscle cells

AIM

To investigate the direct effect of croton oil (CO) on human intestinal epithelial cell (HIEC) and guinea pig colonic smooth muscle cells in vitro.

METHODS

Growth curves of HIEC were drawn by MTT colorimetry. The dynamics of cell proliferation was analyzed with flow cytometry, and morphological changes were observed under light and electron microscopy after long-term (6 weeks) treatment with CO. Expression of cyclooxygenase-2 (COX-2) mRNA was detected by dot blot in HIEC treated with CO. Genes related to CO were screened by DD-PCR, and the direct effect of CO on the contractility of isolated guinea pig colonic smooth muscle cells was observed.

RESULTS

High concentration (20-40 mg x L(-1)) CO inhibited cell growth significantly (1, 3, 5, 7d OD sequence: (20 mg x L(-1)) 0.040+/-0.003, 0.081+/-0.012, 0.147+/-0.022,0.024+/-0.016; (40 mg x L(-1)) 0.033+/-0.044, 0.056+/-0.012, 0.104+/-0.010, 0.189+/-0.006; OD control 0.031+/-0.008, 0.096+/-0.012, 0.173+/-0.009, 0.300+/-0.016, P<0.01), which appeared to be related directly to the dosage. Compared with the control, the fraction number of cells in G1 phase decreased from 0.60 to 0.58, while that in S phase increased from 0.30 to 0.34 and DNA index also increased after 6 weeks of treatment with CO (the dosage was increased gradually from 4 to 40 mg x L(-1)). Light microscopic observation revealed that cells had karyomegaly, less plasma and karyoplasm lopsidedness. Electron microscopy also showed an increase in cell proliferation and in the quantity of abnormal nuclei with pathologic mitosis. Expression of COX-2 mRNA decreased significantly in HIEC treated with CO. Thirteen differential cDNA fragments were cloned from HIEC treated with CO, one of which was 100 percent homologous with human mitochondrial cytochrome C oxidase subunit II. The length of isolated guinea pig colonic smooth muscle cells was significantly shortened after treatment with CO (P<0.05).

CONCLUSION

At a high CO concentration (>20 mg x L(-1)), cell growth and proliferation are inhibited in a dosage-dependent manner. Increase in cell proliferation and in malignant conversion of the cellular phenotype is observed in cells cultured chronically with CO. COX-2 mRNA expression decreases significantly, while human mitochondrial cytochrome C oxidase subunit IImRNA expression increases significantly in HIEC treated with CO. CO also has a direct effect on the contractility of Guinea pig colonic smooth muscle cells.

Effect of cholecystokinin and secretin on contractile activity of isolated gastric muscle strips in guinea pigs

AIM: To study the effect of cholecystokinin-octapeptide (CCK- 8) and secretin on contractile activity of isolated gastric muscle strips in guinea pigs.

METHODS: Each isolated gastric muscle strip was suspended in a t issue chamber containing 5 mL Krebs solution constantly warmed by water jacked at 37 °C and supplied with a mixed gas of 95% O₂ and 5% CO₂. After incubating for 1h under 1g tension, varied concentrations of CCK-8 and se cretin were added respectively in the tissue chamber and the contractile response was measured isometrically on ink-writing recorders.

RESULTS: CCK-8 could increase ① all regional circular and longitudinal muscular tension at rest (fundus LM 19.7% ± 2.1%, P < 0.01; fundus CM 16.7% ± 2.2%, P < 0.01; gastric body LM 16 .8% ± 2.3%, P < 0.01; body CM 12.7% ± 2.6%, P < 0.01; antrum LM 12.3% ± 1.3%, P < 0.01; antrum CM 16.7% ± 4.5%, P < 0.01; pylous CM 12.7% ± 5.0%, P < 0.05); ② contractile frequencies of body LM, both LM and CM of antrum and pylorus CM (5.1/min ± 0.2/min to 5.6/min ± 0.2/min, 5.9/min ± 0.2/min to 6.6/min ± 0.1/min, 5.4/min ± 0.3/min to 6.3/min ± 0.4/min, 1.3/min ± 0.2/min to 2.3/min ± 0.3/min, respectively, P < 0.05); ③ the mean contractile amplitude of antral circular mus cle (58.6% ± 18.4%, P < 0.05) and ④ the motility index of pylorus CM (145.0% ± 23.8%, P < 0.01), but decrease the mean contractile ampl itude of gastric body and antral LM (-10.3% ± 3.3%, -10.5% ± 4.6%, respectively, P < 0.05). All the CCK-8 effects were not blocked by atropine or ind omethacin. Secretin had no effect on gastric smooth muscle activity.

CONCLUSION: CCK-8 possessed both excitatory and inhibitory action on contractile activity of different regions of stomach in guinea pigs.Its action was not mediated via cholinergic M receptor and endogenous prostaglandin receptor.