Abstract:

Objective  To investigate the effect of growth hormone secretagogue receptor agonist ghrelin on the colon motility of morphine induced bowel dysfunction of mice. Methods  Phenolsulfonphthalein pushing test in vivo and contraction test of colonic muscle strips in vitro were conducted for 50 C57 mice. For in vivo test, 25 mice were divided into five groups. One group was the control group and mice of other four groups were intraperitoneally injected with saline or different doses (50, 100, and 200 μg/kg) of ghrelin after the model of morphine induced intestinal paralysis was established. The colonic transit of mice was measured by phenolsulfonphthalein pushing test. For in vitro test, 25 mice were also divided into 5 groups, i.e. the control group, morphine group, and three ghrelin groups (ghrelin of 0.1 μmol/L,1 μmol/L, and 10 μmol/L). Mouse colons were harvested and the spontaneous contraction amplitude of colonic muscle strips was recorded by the biological signal system. Results  For in vivo test, colonic propulsive rates of the morphine group were (33.77±0.49)%. After being injected with ghrelin of 50, 100, and 200 μg/kg, colonic propulsive rates were (41.42±1.66)%, (45.86±0.86)%, and (56.84±0.84) %, respectively, which were significantly higher than those of the morphine group (P<0.05). For in vitro test, contractions amplitudes of colon muscle strips of the morphine group were (0.568±0.014) g. After being treated with ghrelin of 0.1 μmol/L, 1 μmol/L, and 10 μmol/L, contraction amplitudes increased to (0.624±0.118), (0.673±0.014), and (0.712±0.125) g, respectively, which were significantly higher than those of the morphine group (P<0.05).  Conclusion  Ghrelin can significantly improve the colonic motility of morphine induced bowel dysfunction of mice.

Key words: growth hormone secretagogue receptor agonist, opioid-induced bowel dysfunction, colonic motility