Influence of Hypoxia on Plasma Glucagon‐Like Peptide‐1 and Leptin Levels in Humans

Altitude exposure has been associated with loss of appetite and weight loss in healthy humans. However, it remains unclear whether endocrine factors contribute to these changes. Leptin and Glucagon like peptide‐1 (GLP‐1) are peptide hormones which play a role in the regulation of appetite and metabolism. Leptin is also a hypoxia inducible gene, however, the influence of hypoxia on GLP‐1 is less clear. We sought to determine the influence of normobaric hypoxia on plasma leptin and GLP‐1 levels in 25 healthy humans (age=30±8 yrs, BMI=25±3 kg/m 2 ). Subjects ingested a controlled meal during normoxia and following a 17‐hr exposure to normobaric hypoxia (12.5% FIO 2 ) with assessment of plasma leptin before the meal and GLP‐1 pre‐meal, at 20 and 40min. post‐meal. Oxygen saturation (O 2 sats) values were monitored and recorded continuously during hypoxia and averaged 83±2% over the course of 17‐hrs. We found that hypoxia caused a significant elevation in plasma leptin levels (normoxia=4.9±0.8, hypoxia=7.7±1.5ng/mL, p<0.05), but no change in GLP‐1 values (baseline=15.7±0.9 vs. 15.9±0.7pmol/L, 20min post meal=21.7±0.9 vs. 21.8±1.2pmol.L, 40 minutes post meal=19.7±1.2 vs. 21.0±1.2pmol/L, for normoxia and hypoxia, respectively, p>0.05 normoxia vs. hypoxia at each point). There was a moderate correlation between O 2 sats and leptin over the 17hr exposure (r=0.45, p<0.05), but no relationship between O 2 sats and GLP‐1. These data suggest that changes in plasma leptin levels are associated with the degree of O 2 desaturation with exposure to 12.5% FIO 2 whereas, changes in GLP‐1 appear independent of changes in O 2 sats. HL71478, AHA 0410073Z.