[Effect of Fagopyrum cymosum (Trev.) Meisn alcohol extract on defecation and isolated colon of diarrhea-IBS rats and its mechanism].

OBJECTIVE

To explore the intervention of Fagopyrum cymosum (Trev.) Meisn alcohol extract (FAE) on defecation function and motor functions of isolated colons of diarrhea-predominant irritable bowel syndrome (D-IBS) rats and to study its underlying mechanism.

METHODS

The D-IBS rat model was established by neonatal pups maternal separation (NMS) combined with intracolonic infusion of acetic acid (AA). Adult IBS rats were randomly divided into the pre-intervention control group (n = 10, with no gastrogavage), the normal saline control group (n = 10, administered with normal saline by gastrogavage), the pre-treatment model group (n = 8,with no gastrogavage),the normal saline model group (n = 8, administered with normal saline by gastrogavage), the low dose FAE group (n = 8, administered with 6 g/kg FAE by gastrogavage), the high dose FAE group (n = 8, administered with 24 g/kg FAE by gastrogavage), and the Pinaverium Bromide group (n = 8, administered with 0.02 g/kg Pinaverium Bromide by gastrogavage). All medication was performed once daily for 2 weeks. The abdominal withdrawal reflex (AWR) was employed to evaluate the visceral hypersensitivity; their loose and watery stool grade was assessed by Bristol scores for stool consistency; and their fresh feces weight was calculated. In vitro effect of different concentrations of FAE and Pinaverium Bromide (0.02 μg/mL) on spontaneous contraction and spasmodic contraction induced by acetylcholine (Ach) in rats' isolated colon were observed and the influence on the intestinal calcium channel was evaluated.

RESULTS

Compared with the pre-intervention control group, the pain pressure threshold and the maximum tolerance pressure decreased significantly in the pre-intervention model group (P < 0.05), and the loose and watery stool grade and fresh feces weight increased drastically (P < 0.01). Compared with the normal saline control group, the pain pressure threshold and the maximum tolerance pressure decreased significantly in the normal saline model group (P < 0.05), and the loose and watery stool grade and fresh feces weight increased markedly (P < 0.01). Compared with the normal saline model group, the pain pressure threshold of 24 g/kg FAE and Pinaverium Bromide group significantly increased (P < 0.05). The loose and watery stool grade and fresh feces weight decreased obviously in the low dose FAE group, the high dose FAE group, and the Pinaverium Bromide group (P < 0.05). FAE (30, 100, 300, 1,000, and 3,000 μg/mL) and Pinaverium Bromide could significantly inhibit spontaneous contraction of isolated intestines (P < 0.05, P < 0.01), and FAE (30, 100, and 300 x 10(-6) g/mL) could remarkably inhibit their spasmodic contraction and contractile tension induced by Ach and Ca2+ respectively (P < 0.05, P < 0.01) in a concentration-dependent manner. Pinaverium Bromide also could significantly inhibit Ach and Ca2+ induced contraction.

CONCLUSIONS

Effective components of FAE improved the defecation function and inhibited enterospasm induced intestinal hyperactivity in IBS model rats via antagonizing calcium channel competitively and inhibiting colonic motility dose-dependently.