Subject standardization, acclimatization, and sample processing affect gut hormone levels and appetite in humans

Area of Science:

• Endocrinology
• Metabolism
• Nutritional Science

Background:

• Gut hormones are key targets for obesity and type 2 diabetes treatments.
• Controversy exists regarding factors influencing gut hormone levels, including adiposity, diet, and surgery.
• Methodological differences may explain discrepancies in gut hormone concentration studies.

Purpose of the Study:

• To investigate the impact of study-induced stress, prior food consumption, and sample processing on appetite and gut hormone levels.
• To determine if methodological variations contribute to conflicting findings on gut hormone concentrations.
• To establish standardized protocols for accurate gut hormone assessment.

Main Methods:

• A 4-way crossover study involving 10 normal-weight males.
• Measurement of fasting appetite scores, plasma acyl-ghrelin, active glucagon-like peptide-1 (GLP-1), and peptide YY3-36 (PYY3-36).
• Assessment of variables including study-induced stress, prior food intake, and sample processing techniques.

Main Results:

• Study visit order influenced anxiety, cortisol, and PYY3-36 levels, with higher levels on the first day.
• Previous evening's meal affected baseline hunger, PYY3-36, and GLP-1 levels despite a 14-hour fast.
• Specific sample processing methods (acidification, esterase inhibition, dipeptidyl-peptidase IV inhibition) are required for accurate acyl-ghrelin and GLP-1 measurements.

Conclusions:

• Accurate assessment of appetite and gut hormones necessitates standardized prior food consumption and subject acclimatization.
• Specialized sample processing is vital for measuring the labile acyl-ghrelin and active GLP-1.
• Standardized protocols are essential to resolve discrepancies in gut hormone research.