Secretin infusion decreases food intake in healthy men – a randomized, placebo-controlled, double-blind, crossover study

Design: The hormone secretin, best known for regulating pH in the duodenum, has anorectic properties in mice proposedly mediated via secretin-induced brown adipose tissue (BAT) activation. We investigated the effects of exogenous secretin on ad libitum food intake, BAT activity, and postprandial physiology in healthy male volunteers. Methods: In a randomized, placebo-controlled, double-blind, crossover study, 25 healthy men underwent two 5-h i.v. infusions of secretin (1 pmol/kg/min) and placebo (saline), respectively, with an interposed 2-month wash-out period. After 30 min of infusion, a standardized liquid-mixed meal was ingested, and after 5 h, food intake and meal duration were assessed during an ad libitum meal test. Brown adipose tissue activity was assessed regularly by thermal imaging-measured supraclavicular skin temperature. Results: Compared with placebo, secretin significantly decreased ad libitum food intake by 173 ± 88 kcal (95% CI, 0.76-0.99, P =. 039) but did not alter ad libitum meal duration. Secretin acutely decreased BAT activity but increased it postprandially compared with placebo. Acetaminophen-assessed gastric emptying was not affected by exogenous secretin, but secretin increased gallbladder volume, bile acid synthesis, and circulating levels of lipase, amylase, and triglycerides, while decreasing plasma Na+. Compared with placebo, secretin infusion was associated with 24.0 ± 10.8% (95% CI, 0.3-1, P =. 025) more adverse events (headache, nausea, diarrhea, and vomiting). Conclusions: In healthy men, secretin infusion decreased ad libitum food intake concomitantly with a postprandial increase in BAT activity as assessed by thermal imaging-measured supraclavicular skin temperature.