Ghrelin对大鼠十二指肠肌电活动的影响及作用机制

目的:探讨ghrelin对大鼠进食期和消化间期十二指肠肌电活动的影响及作用机制.方法:大鼠十二指肠埋置银丝电极,采用多道生理记录仪监测十二指肠肌电活性,观察进食期和消化间期静脉.给予ghrelin对大鼠十二指肠肌电活动的影响.分别给予阿托品、酚妥拉明、普萘洛尔、L-精氨酸及ghrelin受体拮抗剂(D-Lys3)GHRP-6拮抗ghrelin,探讨ghrelin对肌电活动的作用机制.结果:进食期给予ghrelin提前诱发十二指肠移行性复合肌电活动(migrating myoelectrical complex,MMC);消化间期给予曲ghrelin可使十二指肠MMC周期和Ⅲ相时程缩短,Ⅲ相频率和振幅增加,但Ⅲ相占MMC周期百分比无显著性改变.阿托品、L-精氨酸和(D-Lys3)GHRP-6可抑制这种效应;酚妥拉明和普纂洛尔对此效应无影响.结论:Ghrelin可促进大鼠十二指肠MMC,这可能是通过胆碱能通路起作用,与NO关系密切.Ghrelin受体GHS-R参与其促动力作用.

Effect of ghrelin on duodenal myoelectric activity in conscious rats

OBJECTIVE: To explore the effect of ghrelin on the duodenal myoelectrical activity during the feeding state and the fasting state in rats. METHODS: One pair of bipolar silver electrodes were chronically implanted in the duodenal serosa of rats for electromyography. The myoelectrical activity was recorded when ghrelin was injected intravenously into rats during the feeding state or the fasting state. Some rats were pretreated with atropine, phentolamine, propranolol, L-arginine, and (D-Lys3)GHRP-6 respectively to explore the mechanism of ghrelin. RESULTS: Duodenal migrating myoelectrical complex (MMC) could be induced by ghrelin in the feeding state. Ghrelin could shorten the length of duodenal MMC cycle and increase the amplitude and frequency of phase III during the fasting state. The percentage of phase III in the MMC cycle did not change. These effects were inhibited by atropine and L-arginine (D-Lys3)GHRP-6, but not by propranolol and phentolamine. CONCLUSION: Ghrelin seems to be closely related to the duodenal motility. The excitatory effect of ghrelin on duodenal MMC might rely on the cholinergic pathway, and have a close relationship with NO. The receptor of ghrelin can regulate its activity.