Meguid Michael M, Glade Michael J, Middleton Frank A
Surgical Metabolism and Nutrition Laboratory, Department Surgery, Neuroscience and Physiology Program, SUNY Upstate Medical University, Syracuse, New York, USA.
Nutrition. 2008 Sep;24(9):832-42. doi: 10.1016/j.nut.2008.06.027.
Roux-en-Y gastric bypass (RYGB) produces rapid and dramatic weight loss in very heavy obese patients. Up to 20% cannot sustain their weight loss beyond 2 to 3 y after surgery.
To identify putative etiologic factors producing post-RYGB weight regain, a literature survey of metabolic changes in very obese and a review of our diet-induced obese RYGB rat model data was done.
Weight regain suggests an imbalance in physiologic mechanisms regulating appetite and metabolic rate. Weight regain occurred in 25% of our rats, produced by return to presurgical energy intake levels. The 75% of rats that sustained weight loss secreted a significantly larger amount of peptide YY (PYY) while suppressing leptin secretion; those that failed were unable to develop or sustain a sufficiently large plasma PYY:leptin ratio. Metabolic consequences of this failure included reversal of initial postsurgical increases in peripheral fatty acid oxidation, anorexigenic activity in the hypothalamic arcuate nucleus and paraventricular nucleus, and the expression of uncoupling protein-2 in adipose tissues, and decreases in hepatic lipogenesis, free tri-iodothyronine secretion, expression of orexigenic activity in the arcuate nucleus and paraventricular nucleus, expression of adenosine monophosphate kinase in adipose tissues, skeletal muscle mitochondrial mass, and endocannabinoid content and appetite.
Weight regain after RYGB occurs in approximately 20% of patients and constitutes a serious complication. Weight regain-promoting consequences are attributed to a failure to sustain elevated plasma PYY concentrations, indicating that combining RYGB with pharmacologic stimulation of PYY secretion in patients after RYGB who exhibit inadequate PYY concentration may increase long-term success of surgical weight reduction in morbidly obese adults.
Roux-en-Y胃旁路术（RYGB）能使极度肥胖患者迅速且显著地减重。高达20%的患者在术后2至3年无法维持体重减轻。
为确定导致RYGB术后体重反弹的潜在病因，对极度肥胖患者的代谢变化进行了文献调查，并回顾了我们饮食诱导肥胖的RYGB大鼠模型数据。
体重反弹表明调节食欲和代谢率的生理机制失衡。我们的大鼠中有25%出现体重反弹，这是由于恢复到术前能量摄入水平所致。75%维持体重减轻的大鼠分泌了大量的肽YY（PYY），同时抑制了瘦素分泌；而体重反弹的大鼠则无法产生或维持足够高的血浆PYY：瘦素比值。这种失衡的代谢后果包括术后外周脂肪酸氧化、下丘脑弓状核和室旁核的厌食活性以及脂肪组织中解偶联蛋白-2表达的最初增加出现逆转，肝脂肪生成、游离三碘甲状腺原氨酸分泌、弓状核和室旁核中促食欲活性的表达、脂肪组织中腺苷单磷酸激酶的表达、骨骼肌线粒体质量以及内源性大麻素含量和食欲降低。
RYGB术后约20%的患者会出现体重反弹，这是一种严重的并发症。体重反弹的后果归因于无法维持血浆PYY浓度升高，这表明对于术后PYY浓度不足的患者，将RYGB与PYY分泌的药物刺激相结合可能会提高病态肥胖成年人手术减重的长期成功率。
