Wisén O, Hellström P M
Department of Internal Medicine, Karolinska Hospital, Stockholm, Sweden.
J Intern Med. 1995 Apr;237(4):411-8. doi: 10.1111/j.1365-2796.1995.tb01195.x.
Gastrointestinal motility is closely linked to the rate at which nutrients become systemically available. Regulation of gastric emptying represents the most important brake against delivery of nutrients to the intestine in excess of digestive and absorptive capacity. In man, gastric emptying is slowed in proportion to the energy density of the meal, which will level out the rate of energy delivery to the duodenum. Studies suggest a more rapid gastric emptying in obesity, although the opposite has been reported in some experimental settings. Moreover, gastric volume is larger in obese individuals and appropriate satiety signals are not triggered in response to gastric distension. Postprandial intestinal transit time in obesity is similar to that in normal-weight subjects, however, despite this fact, intestinal absorption of nutrients is more efficient in obesity. Several regulatory mechanisms for gastrointestinal motility, such as the autonomous and enteric nervous systems and gastrointestinal regulatory peptides, are also of importance for feeding behaviour and metabolism. Dysfunction of the autonomous nervous system has been observed, the sensitivity to cholecystokinin is decreased in obesity, and plasma concentrations of somatostatin and neurotensin are lower than in normal-weight subjects. These changes in regulatory mechanisms favour rapid gastrointestinal transit of ingested nutrients and promote rapid intestinal absorption in obesity and decreased satiety in response to ingested food. It is presently not known whether the observed changes in gastrointestinal motility in obesity represent a primary feature linked to the pathogenesis of such disease.
胃肠动力与营养物质进入全身循环的速率密切相关。胃排空的调节是防止营养物质输送到肠道的最重要制动机制，以避免超过消化和吸收能力。在人类中，胃排空速度与食物的能量密度成比例减慢，这将使十二指肠的能量输送速率趋于平稳。研究表明肥胖者胃排空更快，尽管在一些实验环境中报告的结果相反。此外，肥胖个体的胃容量更大，且胃扩张不会触发适当的饱腹感信号。然而，尽管如此，肥胖者餐后肠道转运时间与正常体重者相似，但肥胖者营养物质的肠道吸收更有效。胃肠动力的几种调节机制，如自主神经系统和肠神经系统以及胃肠调节肽，对进食行为和新陈代谢也很重要。已观察到自主神经系统功能障碍，肥胖者对胆囊收缩素的敏感性降低，生长抑素和神经降压素的血浆浓度低于正常体重者。这些调节机制的变化有利于摄入营养物质在胃肠道快速转运，促进肥胖者肠道快速吸收，并降低对摄入食物的饱腹感。目前尚不清楚肥胖者中观察到的胃肠动力变化是否代表与此类疾病发病机制相关的主要特征。
