Antidiarrheal effect of extract from the bark of Combretum leprosum in mice

Abstract This study investigated the effects of the ethanolic extract from the bark of Combretum leprosum (ECL) on intestinal transit and castor-oil induced diarrhea in mice. The oral administration of ECL (750 and 1000 mg/kg) slowed intestinal transit (ID50 of 455 mg/kg). The ECL (250-1000 mg/kg) reduced castor-oil induced diarrhea, in a time- and dose-dependent manner (p < 0.05). To determine if antidiarrheal effect of ECL involves α2-adrenergic or opioid receptor activation, the mice were pretreated with antagonists of these receptors, yohimbine or naloxone respectively. None of these drugs inhibited the antidiarrheal effect of ECL. To test if antidiarrheal effect of ECL is due to an antisecretory action, we realized the enteropooling assay on rats. The ECL increased bowel content and did not inhibit intestinal fluid secretion increase induced by misoprostol (100 µg/kg, s.c.). To determine if antimotility effect of ECL is due to a reduction on gastric motility, we realized the organ bath assay in the rat fundus stomach. Isotonic recordings show that the carbachol /KCl - induced contraction was not reversed by the addition of ECL. In conclusion, our results suggest that ECL contains antidiarrheal compounds and these compounds could induce a reduction of intestinal tract motility.摘要 本研究探讨了麻风风车子（Combretum leprosum）树皮乙醇提取物（ethanolic extract from the bark of Combretum leprosum, ECL）对小鼠肠道转运及蓖麻油诱导腹泻的影响。灌胃给予ECL（750与1000 mg/kg）可减慢小鼠肠道转运，其半数有效剂量（ID50）为455 mg/kg。ECL（250~1000 mg/kg）可通过时间与剂量依赖性方式减轻蓖麻油诱导的腹泻（p < 0.05）。为明确ECL的抗腹泻作用是否涉及α2肾上腺素能受体（α2-adrenergic receptor）或阿片受体（opioid receptor）激活，本研究分别采用育亨宾（yohimbine）与纳洛酮（naloxone）作为上述受体的拮抗剂对小鼠进行预处理。结果显示，两种拮抗剂均未抑制ECL的抗腹泻作用。为验证ECL的抗腹泻作用是否源于抗分泌机制，本研究对大鼠开展了肠内容物蓄积试验（enteropooling assay）。ECL可增加肠道内容物量，且未抑制米索前列醇（misoprostol，100 µg/kg，皮下注射s.c.）诱导的肠液分泌增加。为探究ECL的抗肠道运动作用是否由胃运动减弱介导，本研究采用大鼠胃底组织开展器官浴槽实验（organ bath assay）。等张记录结果显示，卡巴胆碱/氯化钾（carbachol/KCl）诱导的收缩反应并未因ECL的加入而被逆转。综上，本研究结果表明ECL中含有抗腹泻活性成分，此类成分可通过降低肠道转运动力发挥作用。