Predictors of Postabsorptive Ghrelin Secretion after Intake of Different Macronutrients

• Published in: The journal of clinical endocrinology and metabolism Vol. 91; no. 10; pp. 4124 - 4130
• Main Authors: Marzullo, P., Caumo, A., Savia, G., Verti, B., Walker, G. E., Maestrini, S., Tagliaferri, A., Di Blasio, A. M., Liuzzi, A.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Oxford University Press 01.10.2006; Endocrine Society
• Subjects: Adult; Area Under Curve; Biological and medical sciences; Body fat; Body Mass Index; Carbohydrates; Endocrinopathies; Energy balance; Energy expenditure; Energy Metabolism; Entropy; Female; Fundamental and applied biological sciences. Psychology; Ghrelin; Humans; Insulin - metabolism; Insulin resistance; Insulin Secretion; Intestinal Absorption; Leptin; Leptin - metabolism; Lipids; Male; Medical sciences; Nighttime; Obesity; Obesity - metabolism; Peptide Hormones - metabolism; Secretion; Vertebrates: endocrinology; Nutrition; Diet; Ghrelin; Secretion; Predictive factor; Macronutrient; Endocrinology; Feeding
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2006-0270

Context: Release of ghrelin, a gastrointestinal hormone regulating feeding and energy balance, is blunted in obesity, a condition associated with insulin resistance. Objective: The objective was to identify anthropometric and metabolic predictors of postabsorptive ghrelin secretion. Design: We evaluated ghrelin, insulin, glucose, and leptin secretion overnight and after intake of different macronutrients. Subjects: Ten obese subjects (age, 31.8 ± 2.5 yr; body mass index, 43.4 ± 0.8 kg/m2) and six lean subjects (age, 33.5 ± 2.4 yr; body mass index, 21.8 ± 1.4 kg/m2) participated in the study. Main Outcome Measures: The main outcome measures were resting energy expenditure (REE); fat mass; nighttime approximate entropy (ApEn) and synchronicity (cross-ApEn) of ghrelin, insulin, and leptin; insulin sensitivity by homeostatic model approach insulin-sensitivity (HOMA-S%); postabsorptive area under the curve (AUC); and Δ of ghrelin, insulin, glucose, and leptin after carbohydrate-, lipid-, and protein-rich test meals. Results: Nighttime ApEn scores were higher in obese than lean subjects (P < 0.01). Cross-ApEn revealed a synchronicity between ghrelin-insulin, ghrelin-leptin, and insulin-leptin in both groups. Compared with baseline, ghrelin decreased significantly (P < 0.01) in lean and obese subjects after carbohydrates (42.2 vs. 28.5%; P < 0.05), lipids (40.2 vs. 26.2%; P < 0.01), and proteins (42.2 vs. 26.3%; P < 0.01) devoid of between-meal ghrelin differences. Significant associations occurred between nocturnal ghrelin ApEn and insulin (r = 0.53; P < 0.05), postmeal ghrelin AUCs and REE (r = −0.57; P < 0.05), and HOMA-S% (r = 0.52; P < 0.05), postmeal ghrelin Δ and HOMA-S% (r = 0.60; P < 0.05). REE (β = −0.57; P = 0.02) and ghrelin ApEn (β = −0.62; P = 0.01) were predictors of postmeal ghrelin AUC and Δ, respectively. Conclusions: Obesity determined a decreased orderliness of ghrelin secretion and a relative loss of ghrelin-insulin synchrony. Postabsorptive ghrelin secretion decreased significantly both in obese and lean subjects, was related to insulin sensitivity, and was predicted by energy expenditure and hormone pulsatility.