Changes in Gastrointestinal Hormones after the Roux-en-Y Gastric Bypass Procedure: A Review

Changes in Gastrointestinal Hormones after the Roux-en-Y Gastric

Bypass Procedure: A Review

JOURNAL OFTHE AMERICAN DIETETICASSOCIATION

Beckman et al.J Am Diet Assoc. 2010; Volume 110 (April).

Lauren M. Beckman, MS, RD: University of Minnesota (UM)

Tiffany R. Beckman, MD, MPH: UM Carrie P. Earthman, PhD, RD, LD: UM


Gastrointestinal (GI) Hormones and Leptin Characteristics

Hormone GI Hormone

Secreted By Effect on Appetite

Mechanism of Action

Glucagon-Like Peptide-1 (GLP-1)

Yes L-cells of the gut in response to energy intake

Promotes satiety

Slows gastric emptying, promotes insulin release, inhibits glucagon and gastric acid secretion, and acts on the central nervous system

Peptide YY (PYY)

Yes L-cells of the gut in response to energy intake

Promotes satiety

Slows gastric emptying, inhibits gastric acid secretion, and and acts on the central nervous system

Leptin No - adipocytokine

Adipocytes in proportion to adipose tissue mass

Not applicable

Acts on the hypothalamus to decrease food intake and increase energy expenditure

Ghrelin Yes Pituitary gland and stomach

Stimulates appetite

Increases GI motility and decreases insulin secretion

Changes in Gastrointestinal Hormones After the Roux-en-Y Gastric Bypass Procedure: A Review



Effect of Weight Loss on Gastrointestinal Hormones and Leptin Concentrations

Glucagon-Like Peptide-1 (GLP-1)

Peptide YY (PYY)

Leptin Ghrelin

Weight loss




Gastrointestinal Hormones and Leptin Response after Roux-en Y Gastric Bypass (RYGB)

Post-RYGB Glucagon-Like Peptide-1 (GLP-1)

Post-RYGB Peptide YY (PYY)

Post-RYGB Leptin

Post-RYGB Ghrelin

Lean/Normal weight

Overweight

Obese

Other weight loss surgery No data

Weight loss via diet/exercise No data No data

Pre-RYGB




Glucagon-Like Peptide-1 (GLP-1) after Roux-en Y Gastric Bypass (RYGB)

• When post-RYGB patients were still considered obese, GLP-1 levels were significantly higher compared to lean

• Suggests that a component of the RYGB procedure alters the GLP-1 profile

• GLP-1 is secreted from the distal ileum in response to nutrient intake

• Increased GLP-1 levels post-RYGB hypothesized to occur due to surgical component that promotes more rapid delivery of nutrients to the distal gut




• PYY response to a test meal or an oral glucose tolerance test was exaggerated, occurred earlier, and remained elevated above baseline levels for the remainder of the sampling time period

• Occurs as early as 2 days post-RYGB, prior to any weight loss

• In some studies the effect was seen as long as 6 months post-RYGB

Peptide YY (PYY) after Roux-en Y Gastric Bypass (RYGB)




Leptin after Roux-en Y Gastric Bypass (RYGB)

• Studies that examined the correlation between anthropometric measurements and leptin levels found:• Change in leptin concentration significantly correlated with

change in BMI, body weight, and fat mass




Ghrelin after Roux-en Y Gastric Bypass (RYGB)

• Ghrelin reduction post-RYGB first reported by Cummings et al. in 2002, who also found that ghrelin levels were significantly increased following weight loss due to caloric restriction• This suggests that RYGB had a positive effect on the

“hunger hormone” while other methods of weight loss did not





• Ghrelin significantly decreases immediately post-RYGB• One study reported reduction 30 minutes post-RYGB

• Evidence documents decreased ghrelin is maintained for more than one year post-RYGB

• Consistent finding of decreased ghrelin levels post-RYGB offers a partial explanation for the success of the procedure• Low ghrelin levels would not contribute to feelings of

hunger and thereby weight gain





• Possible component of RYGB that promotes altered ghrelin:• Distal stomach (site of ghrelin release) is bypassed

ghrelin secretion is suppressed hunger is reduced





• To determine what component of the RYGB is responsible for the changes in ghrelin, one study collected plasma immediately before, during, and after the procedure and found the greatest decline after dividing the stomach

BLOOD COLLECTION TIME POINTS




Summary

• Glucagon-Like Peptide-1 (GLP-1), Peptide YY (PYY), leptin, and ghrelin change favorably after Roux-en Y Gastric Bypass (RYGB)

• Compared to those undergoing other surgical procedures, those who are normal weight, overweight, or obese, or who lost weight by conventional methods, post-RYGB patients have:• Increased GLP-1 and PYY• Decreased ghrelin• Decreased leptin in proportion to body weight



Documents

Changes in Gastrointestinal Hormones after the Roux-en-Y Gastric Bypass Procedure: A Review