飢餓激素與肥胖抑制素對於乙醇引起胃粘膜損傷的保護作用及相關機制之研究

Gastroprotective effect of Ghrelin / Obestatin on ethanol-induced gastric damage and the underlying mechanism

王心慈(Hsin-Tzu Wang)

指導教授 ： 楊良友

共同指導教授 ： 蔡麗雪

臺北醫學大學/醫學院/醫學科學研究所/碩士(2012年)

https://doi.org/10.6831/TMU.2012.00034

摘要

Ghrelin一種胜肽類激素，屬於growth hormone-releasing peptide的一種。Obestatin則是一種基因序列與ghrelin基因序列位於同一條基因的胜肽類激素。近年來發現ghrelin及obestatin有抗發炎的作用。本實驗探討ghrelin與obestatin是否能抑制乙醇引起的胃損傷及其作用機轉。
本實驗使用雄性ICR小鼠，給予傷害的方式為灌食絕對酒精(0.2 ml/mice)；實驗組別分別為控制組、乙醇單獨傷害組、ghrelin (3, 6 nmol/kg, i.p.)預投予組及obestatin (125, 250 nmol/kg i.p.)預投予組。初步的實驗結果顯示，不同濃度的ghrelin (3, 6 nmol/kg)與obestatin (125, 250 nmol/kg)可有效地降低乙醇引發之潰瘍面積。給予乙醇傷害之後，LPO指標─MDA顯著上升，而ghrelin預投予組(3, 6 nmol/kg)及obestatin預投予組(125, 250 nmol/kg)，LPO程度則顯著低於乙醇單獨傷害組。體內抗氧化物質GSH，在乙醇傷害後顯著地下降，而較高濃度的ghrelin (6 nmol/kg)及obestatin (250 nmol/kg)可抑制GSH的下降。發炎反應指標MPO的活性，在乙醇傷害後顯著地上升，而ghrelin (3, 6 nmol/kg)與obestatin(250 nmol/kg)預投予，可有效地抑制MPO上升。給予乙醇傷害1小時後，發炎反應蛋白cyclooxigenase-2 (COX-2)及其產物Prostaglandin E2在胃組織中顯著地上升，但有經過ghrelin (3, 6 nmol/kg)或obestatin (125, 250 nmol/kg)預投予的組別，COX-2顯著地下降，且較高劑量的ghrelin與obestatin可使PGE2顯著降低。Ghrelin (3, 6 nmol/kg)與 obestatin(250 nmol/kg)預投予也可顯著降低乙醇誘發的iNOS蛋白表現，並且ghrelin (3, 6 nmol/kg)或obestatin (250 nmol/kg)預投予皆可顯著降低血清中NO含量。
目前的實驗證明，脂質過氧化、還原態谷胱甘肽及發炎反應與乙醇引發的胃黏膜傷害有密切的關係，而ghrelin與obestatin則有保護胃臟對抗乙醇傷害的作用，並且此作用可能是透過對於COX-2與iNOS的抑制作用。

關鍵字

飢餓激素 ； 肥胖抑制素 ； 酒精性胃潰瘍 ； 氧化壓力 ； 一氧化氮 ； 前列腺素E2

並列摘要

Ghrelin, a peptide produced by the stomach, was shown to exert a potent protective action on the stomach of rats exposed to ethanol or stress. In addition, obestatin is a peptide encoded by the same gene that also encodes ghrelin. Our objective was to evaluate the possible anti-oxidant and the underlying mechanism of ghrelin and obestatin against ethanol-induced gastric damage.
In vivo assay revealed stomach damage in ICR mice treated with absolute ethanol (0.2 ml/mice) alone; however, the stomach condition of mice co-treated with ghrelin or obestatin and ethanol matched that of the control group. Ghrelin (3 nmol/kg-6 nmol/kg, i.p.), significantly prevented gastric ulcerogenesis induced by ethanol and decreased the ulcer index. Gastric LPO activity that was increased significantly by ethanol was decreased after treatment with ghrelin. Ghrelin treatment increased significantly the gastric GSH levels, and pretreatment with and ethanol decreased it significantly. The MPO level that was increased significantly by ethanol was decreased in pretreatment with ghrelin groups. In the obestatin (125 nmol/kg-250 nmol/kg, i.p.) groups, the results were similar to ghrelin groups. The results of protein expression involved in ethanol-induced inflammation and oxidation, the ghrelin and obestatin pretreatments could significantly reduce the ethanol-induced COX-2 and PGE2 expression. Both of ghrelin and obestatin pretreatments significantly reduced the iNOS in gastric tissues and the NO quantities of plasma.
These findings suggest that active oxygen species, LPO, GSH and MPO have an important role in the pathogenesis of gastric mucosal damage induced by ethanol and that ghrelin and obestatin may be protective against this damage, and the protection might involve in COX-PG and NOS-NO pathways.

並列關鍵字

Ghrelin ； Obestatin ； ethanol-induced gastric ulcer ； Oxidative stress ； NO ； PGE2

參考文獻

1. Park, S.W., Oh, T.Y., Kim, Y.S., Sim, H., Park, S.J., Jang, E.J., Park, J.S., Baik, H.W., and Hahm, K.B. 2008. Artemisia asiatica extracts protect against ethanol-induced injury in gastric mucosa of rats. Journal of gastroenterology and hepatology 23:976-984.

2. Szabo, S., Trier, J.S., Brown, A., and Schnoor, J. 1985. Early vascular injury and increased vascular permeability in gastric mucosal injury caused by ethanol in the rat. Gastroenterology 88:228-236.

4. Ogusucu, R., Rettori, D., Netto, L.E., and Augusto, O. 2009. Superoxide dismutase 1-mediated production of ethanol- and DNA-derived radicals in yeasts challenged with hydrogen peroxide: molecular insights into the genome instability of peroxiredoxin-null strains. The Journal of biological chemistry 284:5546-5556.

5. Liu, E.S., and Cho, C.H. 2000. Relationship between ethanol-induced gastritis and gastric ulcer formation in rats. Digestion 62:232-239.

8. Szelenyi, I., and Brune, K. 1988. Possible role of oxygen free radicals in ethanol-induced gastric mucosal damage in rats. Digestive diseases and sciences 33:865-871.