Published online Nov 14, 2017. doi: 10.3748/wjg.v23.i42.7563
Peer-review started: July 20, 217
First decision: August 21, 2017
Revised: September 8, 2017
Accepted: September 19, 2017
Article in press: September 19, 2017
Published online: November 14, 2017
To investigate the effect of Hemp seed soft capsule (HSCC) on colonic ion transport and its related mechanisms in constipation rats.
Sprague-Dawley male rats were randomly divided into three groups: normal group, constipation group and HSSC group. Rats in the constipation and HSSC groups were administrated loperamide 3 mg/kg per day orally for 12 d to induce the constipation model. Then, the HSSC group was given HSSC 0.126 g/kg per day by gavage for 7 d. The normal and constipation groups were treated with distilled water. After the treatment, the fecal wet weight and water content were measured. The basal short-circuit current (Isc) and resistance were measured by an Ussing Chamber. Besides the in vivo drug delivery experiment above, an in vitro drug application experiment was also conducted. The accumulative concentrations of HSSC (0.1 mg/mL, 0.5 mg/mL, 1.0 mg/mL, 2.5 mg/mL, 5.0 mg/mL, 10.0 mg/mL and 25.0 mg/mL) were added to the normal isolated colonic mucosa and the Isc was recorded. Further, after the application of either ion (Cl- or HCO3-) substitution, ion channel-related inhibitor (N-phenylanthranilic acid, glybenclamide, 4,4-diisothiocyano-2,2-stilbenedisulfonic acid or bumetanide) or neural pathway inhibitor [tetrodotoxin (TTX), atropine, or hexamethonium], the Isc induced by HSSC was also measured.
In the constipation group, the fecal wet weight and the water content were decreased in comparison with the normal group (P < 0.01). After the treatment with HSSC, the fecal wet weight and the water content in the HSSC group were increased, compared with the constipation group (P < 0.01). In the constipation group, the basal Isc was decreased and resistance was increased, in comparison with the normal group (P < 0.01). After the treatment with HSSC, the basal Isc was increased (P < 0.05) and resistance was decreased (P < 0.01) in the HSSC group compared with the constipation group. In the in vitro experiment, beginning with the concentration of 1.0 mg/mL, differences in Isc were found between the experimental mucosa (with HSSC added) and control mucosa. The Isc of experimental mucosa was higher than that of control mucosa under the same concentration (1.0 mg/mL, P < 0.05; 2.5-25 mg/mL, P < 0.01). After the Cl- or HCO3- removal and pretreated with different inhibitors (cAMP-dependent and Ca2+-dependent Cl- channels, Na+-K+-2Cl- cotransporter (NKCC), Na+-HCO3- cotransporter or Cl-/HCO3- exchanger inhibitor), there were differences between experimental mucosa and control mucosa; the Isc of experimental mucosa was lower than that of control mucosa under the same concentration (P < 0.05). Meanwhile, after pretreatment with neural pathway inhibitor (TTX, atropine, or hexamethonium), there were no differences between experimental mucosa and control mucosa under the same concentration (P > 0.05).
HSSC ameliorates constipation by increasing colonic secretion, which is mediated via the coaction of cAMP-dependent and Ca2+-dependent Cl- channels, NKCC, Na+-HCO3- cotransporter or Cl-/HCO3- exchanger.
Core tip: In this study, we established a constipation model using the application of loperamide and found that Hemp seed soft capsule could improve the symptom of constipation. Further, it was found that the effect of Hemp seed soft capsule might be achieved by increasing colonic secretion, which is mediated via the combined action of cAMP-dependent and Ca2+-dependent Cl- channels, Na+-K+-2Cl- cotransporter, Na+-HCO3- cotransporter or Cl-/HCO3- exchanger. However, the submucosal neurons seemed to not play a key role in the process.