http://www.medpagetoday.com/Endocrinology/Obesity/50033 Duodenal Switch Key to Bariatric Surgery's Efficacy Murine data suggest switch is the key to long-term results. by Salynn Boyles Contributing Writer Action Points Note that this rat study demonstrated that biliopancreatic diversion with duodenal switch is particularly effective at inducing weight loss. Be aware that this procedure is uncommonly performed in humans due to the complication rate, which is higher than the more-standard Roux-en-Y gastric bypass. Research in rats has shown the duodenal switch component of biliopancreatic diversion with duodenal switch (BPD/DS) to be a key contributor to increased satiety and early resolution of type 2 diabetes following weight-loss surgery. While BPD/DS, sleeve gastrectomy (SG) alone, or duodenal switch (DS) alone all resulted in a short-term reduction in food intake, only BPS/DS and DS alone led to persistent reductions in body weight and body fat and significant decreases in energy intake, Denis Richard, PhD, and colleagues wrote in the journal Endocrinology. The researchers concluded that duodenal switch played a key role in metabolic changes in the high fat (HF) diet-fed rats. "The DS component leads to a reduction in digestible energy intake while sustaining energy expenditure," the researchers wrote. "The intestinal diversion by DS also results in gut morphological changes, which are accompanied by elevation in satiating gut hormones such as (the satiating gut hormones) GLP-1 and PYY." BPD/DS Not Widely Performed In the bariatric procedure known as biliopancreatic diversion with duodenal switch, both the duodenum and the small intestine are divided and the portion of the small intestine is attached to a short duodenal section next to the stomach, which is left largely intact. The remaining section of the duodenum connected to the pancreas and gallbladder is attached to this limb close to the large intestine. More than other bariatric surgery, biliopancreatic diversion with duodenal switch is associated with significant weight loss and metabolic improvements, such as normalization of plasma glucose, insulin triglycerides, and free fatty acids, Richard and colleagues noted. But the demanding surgery also has a higher complication rate than other bariatric procedures, and is performed far less often. Most studies in animals and humans exploring the mechanism driving the metabolic benefits of weight-loss surgery have involved Roux-en-Y intestinal bypass (RYGB) or sleeve gastrectomy, the researchers noted. "The main objective of the present study was to delineate the contributions of SG and DS to the metabolic improvements produced by the BPD/DS in rats fed HF to induce obesity" they wrote. Over a 9-week period following surgery, energy balance measurements were performed by Richard and colleagues in BPD/DS, DS, SG, and sham-operated male Wistar rats. Changes in plasma levels of gastrointestinal (GI) hormones were evaluated at the end of the 9 weeks. Researchers estimated the thermogenic activity of interscapular brown adipose tissue (iBAT) using the positron emission tomography (PET) tracers 11C-acetate (oxidative activity) and 14-R,S-18F-fluoro-6-thiaheptadecanoic acid (18FTHA -- free fatty acid uptake). The expression of genes encoding proteins involved in BAT thermogenesis and fatty acid oxidation was also examined. Energy Expenditure Not Related to Increased iBAT Among the study findings: BPD/DS and DS, but not SG, resulted in persistent reductions in body weight gain and body fat, which were accompanied by a significant decrease in digestible energy intake. BPD/DS and DS also exhibited a reduction in energy expenditure, which was not totally accounted for by the reduction in body weight promoted by the surgeries; energy expenditure was slightly higher in BPD/DS rats than in sham high fat, pair weighted (Sham HF PW) animals. BPD/DS and DS reduced iBAT oxidative activity (estimated from 11C-acetate) to the level seen in sham HF PW animals. BPD/DS and DS led to significant elevations in GLP-1 and PYY levels. These findings show the importance of the DS component of BPD/DS in creating a negative energy balance through reducing digestible energy intake, the researchers noted. "The DS component is unique to the BPD/DS and likely behind the established efficacy of the procedure to treat obesity and resolve type 2 diabetes," they wrote. The finding that BPD/DS rats ate more than sham HF PW rats to maintain the same body weight and fat mass showed the ability of BPD/DS to also stimulate energy expenditure, the researchers noted. The sustained energy expenditure did not appear to be accomplished through an increase in iBAT thermogenesis. "BAT is a heat-producing tissue whose activity is mainly controlled by the sympathetic nervous system (SNS) and RYGB has been demonstrated to reduce SNS activity," the researchers wrote. "The mechanisms whereby BPD/DS stimulated energy expenditure while reducing BAT thermogenesis remain to be determined." The researchers reported no funding source and they disclosed no relevant relationships with industry. Reviewed by F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine Primary Source Endocrinology Source Reference: Baraboi ED, et al "Metabolic changes induced by the biliopancreatic diversion in diet-induced obesity in male rats: the contributions of sleeve gastrectomy and duodenal switch" Endocrin 2015; DOI: 10.1210/en.2014-1785. NOTE: I noticed that they are using the term DS as JUST the guts part of the surgery. Not as most of us use it to describe the whole thing, sleeve and guts!