生长激素促分泌素受体对小鼠结肠动力的影响和机制

目的:探讨生长激素促分泌素受体及其激动剂GHRP-6对小鼠结肠动力的影响及机制。方法:小鼠随机分组后,分别注射生理盐水、GHRP-6(20、50、100、200μg/kg),用炭末推进实验的方法研究GHRP-6对小鼠结肠推进的影响。小鼠近端结肠环形平滑肌条安置在恒温灌流肌槽中,并用SMUP-E生物信号处理系统记录肌条的自发收缩活动,观察不同浓度的GHRP-6(0.01、0.1、1和10μmol/L)对肌条自发收缩幅度的影响,以及神经阻断剂TTX和GHS-R阻断剂D-lys3-GHRP-6孵育肌条情况下,GHRP-6对肌条自发收缩幅度的影响。结果:GHRP-6注射剂量在50、100、200μg/kg时均能显著提高小鼠的结肠推进(P0.05)。GHRP-6浓度在0.1、1和10μmol/L时均能显著增加小鼠近端结肠环形平滑肌条的自发收缩幅度(P0.05),在TTX和D-lys3-GHRP-6孵育肌条下,Ghrelin不能增加小鼠结肠环形平滑肌条的自发收缩幅度。结论:GHRP-6可以显著增加小鼠的结肠推进,其机制可能是通过肠肌间神经丛的的GHS-R受体而起作用。

Effects and mechanisms of growth hormone secretagogue receptor on colonic motility of mices

Objective:To investigate the effects and mechanisms of growth hormone secretagogue receptor and its agonist GHRP-6 on colonic motility in mices.Methods:In vivo,the dose depend effects of GHRP-6(20,50,100,200 μg/kg) on colonic transit were measured by charcoal suspension pushing test.In vitro,the effects of GHRP-6(0.01,0.1,1 and 10 μmol/L) on spontaneous contraction of proximal colonic isolated circular muscle strips were studied in the presence of TTX or D-lys3-GHRP-6 or not.Results:GHRP-6(50,100,200 μg/kg) significantly accelerated colonic transit(P<0.05).GHRP-6(0.1,1 and 10 μmol/L)significantly increased the spontaneous contraction of the proximal colonic circular muscle strips(P<0.05),TTX or D-lys3-GHRP-6 can block the reaction.Conclusion:GHRP-6 accelerate colonic transit perhaps by activating GHS-R in the enteric nervous system.