Ghrelin, a novel GH-releasing peptide isolated from human and rat stomach, stimulates food intake and GH secretion. We determined plasma ghrelin concentrations in patients with simple obesity, anorexia nervosa, and type 2 diabetes mellitus by RIA. We also studied plasma ghrelin responses to glucose load and meal intake and obtained a 24-h profile of circulating ghrelin in humans. Plasma ghrelin concentrations in patients with simple obesity and anorexia nervosa were lower and higher, respectively, than those of healthy subjects with normal body weight. Among those with type 2 diabetes mellitus, obese patients had lower and lean patients higher fasting plasma ghrelin concentrations than normal-weight patients. Fasting plasma ghrelin concentration was negatively correlated with body mass index in both nondiabetic and diabetic patients. Plasma ghrelin concentrations of normal subjects decreased significantly after oral and iv glucose administration; a similar response was also observed in diabetic patients after a meal tolerance test, reaching a nadir of 69% of the basal level after the meal. Circulating plasma ghrelin showed a diurnal pattern with preprandial increases, postprandial decreases, and a maximum peak at 0200 h. This study demonstrates that nutritional state is a determinant of plasma ghrelin in humans. Ghrelin secretion is up-regulated under conditions of negative energy balance and down-regulated in the setting of positive energy balance. These findings suggest the involvement of ghrelin in the regulation of feeding behavior and energy homeostasis.

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Objective: Fasting plasma ghrelin levels play an important role in the pathophysiology of the eating disorder anorexia nervosa. Bulimia nervosa (BN) also has been associated with abnormal neuroendocrine regulation. Thus, we examined the relationship between body mass index (BMI) and plasma ghrelin concentrations in patients with BN for the first time. Methods: The subjects included 15 female BN patients and 11 female healthy volunteers (controls). Fasting blood samples were collected from all subjects. Results: The plasma ghrelin concentrations in all subjects demonstrated a significantly negative correlation with BMI. Mean plasma ghrelin level in BN patients was significantly higher than that in the controls, though mean BMIs between the groups were not significantly different. Conclusion: These findings suggest that not only BMI but also abnormal eating behaviors with habitual binge eating and purging may have some influence on circulating ghrelin level in BN.

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