Gastric bypass increases ethanol and water consumption in diet-induced obese rats

Abstract

Background: Roux-en-Y gastric bypass surgery (RYGB) is an effective treatment for morbid obesity. Increased alcohol abuse after RYGB resulted in recommendations to exclude patients with alcohol abuse histories from RYGB. The purpose of our study was to examine the effects of a RYGB on ethanol intake in diet-induced obese rats (high-fat diet).

Methods: The animals underwent RYGB and were habituated along with their sham-operated obese controls and with lean rats to increasing concentrations of ethanol in a two-bottle choice paradigm.

Results: RYGB rats' daily consumption of ethanol averaged 2 g/kg at 2% habituation and 3.8 g/kg at 4% habituation, twice as much as sham-operated obese controls and 50% more than normal-diet lean controls. Obese controls drank on average 1 g/kg of ethanol (2 and 4%), significantly less (50%) than lean controls did. RYGB rats when given higher ethanol concentrations (6 and 8%) or no ethanol drank significantly more water than lean and obese controls did (66 and 100%, respectively), and their enhanced total fluid intake was associated with increased food intake, which was significantly higher than in lean (66% more calories; food + alcohol) and obese controls (44% more calories). The lower alcohol intake in the obese controls than in the lean rats suggests that obesity may interfere with alcohol's rewarding effects and RYGB may remove this protective effect.

Conclusions: The overall enhancement of consummatory behaviors (both ethanol and water) suggests that RYGB may facilitate alcohol consumption, which in vulnerable individuals could lead to abuse and addiction.

Figure 1

Illustration of the rat Roux-en-Y Gastric Bypass Procedure. The stomach is reduced to a small pouch (dashed line) by stapling providing full separation between the gastric pouch and excluded stomach. The pouch then is connected directly to the distal trunk of previously divided jejunum (solid line, no fill). The larger portion of the stomach (dark grey) and the duodenum with the proximal segment of divided jejunum (light grey: bilio-pancreatic limb) is bypassed by food and reconnected to the Roux-Limb to form a common channel.

Figure 2

(a) Experimental Procedure timeline. (b) Mean (Summed Bi-Daily - the sum of two days; ± SEM) EtOH and water intake per kilogram of body weight for gastric bypass (RYGB), sham-operated animals fed a high-fat diet (Sham-HF) and naive-normal diet (Naïve-ND) during access to EtOH at varying concentrations. (c) Mean (± SEM) EtOH intake per kilogram of body weight for each phase of study for RYGB, Sham-HF and Naïve-ND animals during the EtOH drinking period at various concentrations. * p<0.05 as compared to Sham-HF and Naïve-ND, # p<0.05 as compared to Sham-HF (d) Mean (± SEM) water intake per kilogram of body weight for each phase of study for RYGB, Sham-HF and Naïve-ND animals during the study at various concentrations. * p<0.05 as compared to Sham-HF and Naïve-ND, # p<0.05 as compared to Sham-HF

Figure 3

(a) Mean weekly (± SEM) body weight in grams for each group of animals over 31 weeks. (b) Mean weekly (± SEM) food intake in grams for each group. (c) Mean weekly (± SEM) food intake in kilocalories for each group of animals over 31 weeks. (d) Mean weekly (± SEM) normalized food intake in kilocalories per kilogram of body weight for each group.

Figure 4

Mean (± SEM) total fluid intake per kilogram of bodyweight across each phase of study for RYGB, Sham-HF and Naïve-ND animals, * p<0.05 as compared to Sham-HF and Naïve-ND.