Bariatric surgery and obesity: influence on the incretins

Abstract

The gut hormone incretins have an important physiological role in meal-related insulin release and post-prandial glucose control. In addition to weight loss, the incretin hormones have a role in glucose control after bariatric surgery. The release of incretins, and specifically of glucagon-like peptide (GLP)-1, in response to the ingestion of nutrients, is greatly enhanced after gastric bypass (RYGBP). The rapid transit of food from the gastric pouch to the distal ileum is responsible for the greater GLP-1 release after RYGBP. The incretin effect on insulin secretion, or the greater insulin response to oral glucose compared to an isoglycemic intravenous glucose challenge, is severely impaired in patients with type 2 diabetes, but is recovered rapidly after RYGBP. The improvement in insulin secretion rate and β-cell sensitivity to oral glucose after RYGBP is mediated by endogenous GLP-1, and is abolished by exendin 9-39, a specific GLP-1 receptor antagonist. While calorie restriction and weight loss have major effects on the rapid and sustained improvement of fasted glucose metabolism, the enhanced incretin effect is a key player in post-prandial glucose control after RYGBP.

Changes of serum retinol-binding protein 4 associated with improved insulin resistance after laparoscopic sleeve gastrectomy in Chinese obese patients

“…However, the mechanism by which bariatric surgery improves glucose metabolism is unclear. Change of hormone secretion in the gastrointestinal tract may be one of those mechanisms [38,39]. RBP4 plays an important role in insulin resistance, and the improved glucose metabolism after LSG may be related to RBP4.…”

Alterations of Gut Microbiota After Biliopancreatic Diversion with Duodenal Switch in Wistar Rats

“…The predominance of Bifidobacterium in the gut microbiota could reduce low-grade inflammation [34] as well as underlying the raised levels of GLP-1 and PYY following BPD/DS [35]. The latter hormones cause satiating effect [36][37][38], and GLP-1, which is strongly stimulated in BPD/DS animals [5,6], is seen as one of the most potent incretins [8,9,39]. One however needs to remain cautious in linking the rise in Bifidobacterium to the beneficial effects of the surgery as one cannot accurately estimate from the present data how much of the increased relative abundance of Bifidobacteriales was due to the drop of Clostridiales versus the true growth in Bifidobacteriales.…”

“…The beneficial effects of bariatric surgery have been inevitably associated with gut alterations [7]. The surgery increases the secretion of gut hormones GLP-1 and PYY, which are hormones known to reduce food intake and, as for GLP-1, to produce incretin effects [8,9]. In addition, bariatric surgery also appears to induce favorable changes on the gut microbiota [10][11][12].…”

Cracking the combination: Gut hormones for the treatment of obesity and diabetes

“…As noted, Roux‐en‐Y Gastric Bypass (RYGB) surgery has been proven in multiple studies to be an effective treatment for obesity and diabetes . Dramatic changes in gut hormones, namely the rise in postprandial levels of GLP‐1, OXM and PYY even days after the operation, account for the improvement in glycaemic control which can reach diabetes remission as well as for the weight loss and other beneficial metabolic effects such as enhancement of insulin sensitivity and improved lipid profile . We asked whether it might be possible to replicate the benefits of RYGB using a triple hormone infusion of GLP‐1, oxyntomodulin & PYY (GOP for short).…”

“…4 Dramatic changes in gut hormones, namely the rise in postprandial levels of GLP-1, OXM and PYY even days after the operation, account for the improvement in glycaemic control which can reach diabetes remission as well as for the weight loss and other beneficial metabolic effects such as enhancement of insulin sensitivity and improved lipid profile. 91,92 We asked whether it might be possible to replicate the benefits of RYGB using a triple hormone infusion of GLP-1, oxyntomodulin & PYY (GOP for short). In a proof of concept study, we demonstrated that a subcutaneous infusion of GOP hormones in ten obese healthy subjects for 10.5 hours can replicate the post-prandial gut hormone levels seen after RYGB.…”