Effect of the ginsenoside Rb1 on the spontaneous contraction of intestinal smooth muscle in mice

AIM: To investigate the effect and the possible mechanism of ginsenoside Rb1 on small intestinal smooth muscle motility in mice. METHODS: Intestinal smooth muscle strips were isolated from male ICR mice (5 wk old), and the effect of ginsenoside Rb1 on spontaneous contraction was recorded with an electrophysiolograph. The effect of ginsenoside Rb1 on ion channel currents, including the voltage-gated K + channel current (IK V ), calcium-activated potassium channel currents (IK Ca ), spontaneous transient outward currents and ATP-sensitive potassium channel current (IK ATP ), was recorded on freshly isolated single cells using the whole-cell patch clamp technique. RESULTS: Ginsenoside Rb1 dose-dependently inhibited the spontaneous contraction of intestinal smooth muscle by 21.15% ± 3.31%, 42.03% ± 8.23% and 67.23% ± 5.63% at concentrations of 25 μmol/L, 50 μmol/L and 100 μmol/L, respectively (n=5,P<0.05). The inhibitory effect of ginsenoside Rb1 on spontaneous contraction was significantly but incompletely blocked by 10 mmol/L tetraethylammonium or 0.5 mmol/L 4-aminopyridine, respectively (n=5, P<0.05). However, the inhibitory effect of ginsenoside Rb1 on spontaneous contraction was not affected by 10 μmol/L glibenclamide or 0.4 μmol/L tetrodotoxin. At the cell level, ginsenoside Rb1 increased outward potassium currents, and IK V was enhanced from 1137.71 ± 171.62 pA to 1449.73 ± 162.39 pA by 50 μmol/L Rb1 at +60 mV (n=6, P<0.05). Ginsenoside Rb1 increased IK Ca and enhanced the amplitudes of spontaneous transient outward currents from 582.77 ± 179.09 mV to 788.12 ± 278.34 mV (n=5, P<0.05). However, ginsenoside Rb1 (50 μmol/L) had no significant effect on IK ATP (n=3, P<0.05). CONCLUSION: These results suggest that ginsenoside Rb1 has an inhibitory effect on the spontaneous contraction of mouse intestinal smooth muscle mediated by the activation of IK V and IK Ca , but the K ATP channel was not involved in this effect.

Deletion of Gpr128 results in weight loss and increased intestinal contraction frequency

AIM: To generate a Gpr128 gene knockout mouse model and to investigate its phenotypes and the biological function of the Gpr128 gene.

Laxative Effect of Some Plants Extracts Used in Traditional Pharmacopoeia on the Intestine of Rabbit

Constipation is a condition in which a person or animal has difficulty in eliminating solid waste from the body and the faeces are hard and dry. It is mainly characterized by a difficulty in defecation. The aim of the study is to assess the laxative effect of some plants such as Adansonia digitata , Ziziphus mauritiana and Psidium guayava traditionally used in Chad to treat the problems of constipation. The Microdynamometer method (Biomecatronics) is used to carry out this study. The outcomes show that the extracts’ leaves of Psidium guayava and barks of Ziziphus mauritiana did not lead a significant contraction of duodenum of rabbit until a maximum concentration of 1000 μg, but the extracts’ leaves of Adansonia digitata had a significant effect (P < 0.05) on the intestinal motility of rabbit. This effect of the extract of Adansonia digitata varies with the increase of its concentration (dose dependent) with a maximum of 500 μg and the minimal effect is inferior to 10 μg. On the other hand, the extract of Adansonia digitata has a musculotrope effect because the results have shown that inhibitive molecules such as the atropine and the naloxone do not have to inhibit the action of Adansonia digitata on the intestinal motility of rabbit. Thus, the extract of this plant would reduce significantly the time of intestinal transit and it will be an important laxative drug candidate as described traditionally in Chad.