Growth hormone secretagogue participates in two-way regulation of the motility of small intestinal smooth muscle in rats / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of growth hormone secretagogue(ghrelin) on the contraction and relaxation of small intestinal smooth muscle in rats and its mechanism.</p><p><b>METHODS</b>Twenty-four vagotomized rats were injected intraperitoneally with different concentrations of ghrelin (0, 20, 40, 80 μg/kg). The small intestinal transit were observed. The effect of ghrelin(0.01, 0.1, 0.5, 1.0 μmol/L) on the contraction and relaxation of rat small intestinal smooth muscle strips was observed in vitro in the presence of carbachol(50 nmol/L), the locations of ghrelin receptors(GHS-R1a) on different cells in small intestinal muscle layers were detected by immunofluorescence.</p><p><b>RESULTS</b>With the increase of concentrations, ghrelin elevated the percentage of small intestinal transit[(25.4±1.0)%, (33.7±1.9)%, (39.3±2.4)%, (44.7±2.1)%] in a dose-dependent manner, and the differences were statistically significant among groups(P<0.05). Ghrelin could also enhance 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 Cch in a dose-dependent manner, and the differences were statistically significant among groups(P<0.05). Immunofluorescence revealed that ghrelin receptors mainly located on membrane of the nerve cells in the muscle layers, while no receptors were observed on membrane of the smooth muscle cells.</p><p><b>CONCLUSION</b>Ghrelin may enhance the effect of the contraction and relaxation of the rat small intestinal smooth muscle mediated by cholinergic neurotransmitters by activating the nerve cells in the enteric plexus.</p>

Effect of the expression of ghrelin receptors on the postoperative underpowered small intestinal motility in rats / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of the expression of ghrelin receptors on the postoperative small intestine dysmotility in rat models.</p><p><b>METHODS</b>The effect of different concentrations of ghrelin (0, 0.01, 0.1, 0.5, 1.0 μmol/L) on the contraction of smooth muscle strips of rat small intestine in the presence or absence of carbachol was observed in vitro. End-to-side anastomosis was performed in the study group and sham controls were used. The expression of ghrelin receptors(GHS-R1a) in small intestine muscle layers was detected by immunohistochemistry and Western blot.</p><p><b>RESULTS</b>In vitro, ghrelin enhanced the contraction of smooth muscle strips in the presence of carbachol, and the differences in contraction induced by different concentrations of ghrelin(0.1, 0.5, 1.0 μmol/L) were statistically significant [(223±18)%, (245±22)%, (264±25)%, P<0.01]. Immunohistochemistry study showed that GHS-R1a mainly located in the muscular layer of the bowel wall. The expression of GHS-R1a in the circular and longitudinal muscle was significantly weaker than that in the control group. The expression of ghrelin receptors after surgery was down-regulated in the study group, which was lower than that in the control group(0.51±0.02 vs. 0.71±0.01, P<0.01).</p><p><b>CONCLUSION</b>Down regulation of ghrelin receptors in small intestine muscle layers may contribute to the occurrence of small intestine dysmotility after intestinal surgery.</p>