Ghrelin对大鼠小肠平滑肌运动的双相调节

Ghrelin participates in the two-way regulation of the motility of the small intestinal smooth muscle in rats

目的探讨Ghrelin对大鼠小肠平滑肌舒缩活动的影响和机制。方法观察不同浓度Ghrelin（0、20、40、80μg／kg）对迷走神经切断大鼠小肠转运的影响，Ghrelin（0．01、0．1、0．5、1．0μmol／L）对体外大鼠小肠平滑肌肌条舒缩活动的影响，免疫荧光方法检测Ghrelin受体（GHS—R1a）在小肠肌层中不同类型细胞的分布。结果Ghrelin在外周剂量依赖性地增加小肠转运率[（25．4±1．0）％、（33．7±1．9）％、（39．3±2．4）％、（44．7±2．0％]，增强卡巴胆碱引起的肌条收缩[（67．0±2．4）％、（149．5±3．3）％、（187．1±4．7）％、（213．5±3．4）％]和舒张[（35．3±1．1）％、（62．9±3．8）％、（79．6±2．7）％、（94．6±2．2）％]效应，Ghrelin受体主要分布在肠内肌层中的神经细胞膜上，平滑肌细胞膜上无分布。结论Ghrelin可通过直接作用于小肠肌层神经丛中的神经细胞而增强胆碱能神经递质引起的小肠平滑肌的舒缩活动。

Objective To investigate the effect and mechanism of Ghrelin on the contraction and relaxation of rat small intestinal smooth muscle. Methods The effect of different concentrations of Ghrelin （0;20;40;80μg/kg） on the small intestinal transit in vagotomized rats in vivo and Ghrelin （0.01; 0. 1; 0. 5 ; 1.0 μmol/L） on the contraction and relaxation of rat small intestinal smooth muscle strips in vitro was observed, the locations of Ghrelin receptors （GHS-Rla） in small intestinal muscle layers were detected by y. Results Ghrelin dose-dependently increases small intestinal transit （（ 25.4± 1.0）%, （33.7 ±1.9）%, （39.3 ±2.4）%, （44.7 ±2.1）%）, enhances the contraction （（67.0 ± 2.4）%,（149.5 ±3.3）%, （187.1 ±4.7）%, （213.5 ±3.4）%） and relaxation （（35.3 ±1.1）%, （62. 9 ± 3.8 ） %, （ 79. 6 ± 2. 7 ） %, （ 94. 6 ± 2. 2 ） % ） of smooth muscle strips mediated by carhachol. Ghrelin receptors were mainly located on membrane of the nerve cells in the muscle layers, while no receptors exist on membrane of smooth muscle cells. Conclusions Ghrelin enhances the effect of contraction and relaxation of rat small intestinal smooth muscle mediated by cholinergic neurotransmitters activating nerve cells in the enteric plexus.