ABSTRACT
Objective To investigate the effects of ghrelin on colonic motility in mice.Methods The eflfects of ghrelin on colonic propulsive movement were detected by charcoal suspension pushing test after injection of normal saline and different doses of ghrelin(20,50,100,200 ng/g).The effects of atropine,NG-nitro-L-arginine methylester hydrochloride(L-NAME)or D-Lys3-GHRP-6 on the changes of colonic propulsive movement caused by ghrelin(100 ng/g)were also investigated.In vitro,the effects of different doses of ghrelin(0.01,0.1,1,10μmol/L)on the spontaneous contraction amplitude of proximal colonic circular muscle strips were studied.Results Ghrelin significantly accelerated the colonic propulsive movement in dose-dependent manner,but the efiect was significantly inhibited in the presence of atropine,L-NAME or D-Lys3-GHRP-6(t=10.230,12.560,11.590,P＜0.05).Administration of ghrelin significantly increased the contraction amplitude of colonic circular muscle strips.but this effect was inhibited when the colonic circular muscle strips were pretreated by tetrodotoxin.ConclusionsGhrelin can accelerate colonic propulsive movement by activating growth hormone secretagogue receptor of cholinergic excitatory pathways and nitrergic nervous pathways in the enteric nervous system of colon.