Prospective Study of Gut Hormone and Metabolic Changes After Adjustable Gastric Banding and Roux-en-Y Gastric Bypass

Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
International journal of obesity (2005) (Impact Factor: 5). 05/2009; 33(7):786-95. DOI: 10.1038/ijo.2009.79
Source: PubMed


The objective of this study was to quantify hormones that regulate energy and glucose homeostasis to establish possible mechanisms for the greater efficacy of Roux-en-Y gastric bypass (RYGB) compared with laparoscopic adjustable gastric banding (LAGB) in achieving weight loss and improved insulin sensitivity.
Longitudinal study of patients undergoing LAGB (n=15) and RYGB (n=28) who were studied before surgery and at 2, 12, 26 and 52 weeks afterwards.
Fasting blood samples were drawn at each visit. Postprandial blood samples were also obtained before surgery and at 26 and 52 weeks. Samples were assayed for peptide YY (PYY), ghrelin, glucagon-like peptide-1 (GLP-1), glucose, insulin, leptin, thyrotropic hormone, free T(4) and free T(3).Results:At 1 year there was greater weight loss in RYGB compared with LAGB patients (30 vs 15%), but final body mass index was similar (34 vs 33 kg m(-2)). At week 52, area under the curve (AUC) for PYY in RYGB subjects was greater than LAGB (P<0.01). GLP-1 levels at 30 min after meal were threefold greater after RYGB compared with LAGB (P<0.001). Conversely, ghrelin AUC increased after LAGB at week 52 (P<0.05) but tended to decrease after RYGB. Fasting glucose, insulin, and leptin and homeostasis model of assessment (HOMA-IR) decreased in both groups over time but were significantly lower at week 52 after RYGB compared with LAGB. The change in leptin correlated significantly with weight loss in LAGB (r=0.86) and RYGB (r=0.77), however, HOMA-IR correlated significantly with weight loss only in LAGB (r=0.78), and not RYGB (r=0.15). There was a significant decrease in free T(3) (P<0.01) after RYGB.
Differences in levels of gut hormones may play a role in promoting greater weight loss and insulin sensitivity after RYGB compared with LAGB, however, weight loss may be limited by decreases in free T(3) and leptin.

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    • "It is also believed there is an interplay between the microbiome post-RYGB and bile acids in regard to altering their absorption and deconjugation and enhancing overall enterohepatic recycling[79]. In comparison to the hormonal changes observed post- RYGB, GLP-1, OXM, and PYY levels are unchanged or decreased following calorie restriction-induced weight loss and unchanged following LGB[80,81]. This may explain the superiority of RYGB over LGB and calorie restriction in inducing weight loss. "
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    • "Additionally, our findings most likely reflect post-RYGB metabolic and endocrine changes that impact the sensitivity of the brain to alcohol reward. Notably, hormones that have been shown to change after RYGB, such as leptin and ghrelin [26], [27], [28], are also known to modulate the dopaminergic reward system [29], [30], [31] as well as EtOH consumption [32], [33]. Thus, it is conceivable that RYGB may reverse blunted ghrelin signaling in obesity [34], [35], which acting upstream on the dopamine neurons [36], [37], [38], may alleviate reward deficits associated with dietary obesity [39]. "
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    • "However, in a rodent model, postoperative weight loss was correlated with the magnitude of decrease in ghrelin levels [74]. Similar to weight loss induced by lifestyle alterations, the degree of leptin decrease at 1 y after RYGB has been found to correlate with the degree of weight loss [36]. "
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