Plasma obestatin levels are lower in obese and post-gastrectomy subjects, but do not change in response to a meal.

OBJECTIVE: To investigate a potential role for obestatin in humans by examining response to a fixed energy meal. CONTEXT: A new anorectic peptide hormone, obestatin has recently been isolated from rat stomach. The significance of this peptide in humans is unknown. STUDY DESIGN: Case-control study. SETTING: Hospital-based study. PATIENTS: Nine healthy controls, nine morbidly obese subjects and eight post-gastrectomy subjects. INTERVENTION: Subjects attended after an overnight fast and were given a fixed energy meal (1550 kJ). MAIN OUTCOME MEASURE: The response of obestatin to a meal in the different groups. RESULTS: Fasting obestatin was significantly lower in obese subjects as compared to lean subjects (27.8+/-4 vs 17.2+/-2 pg/ml, P=0.03). Obestatin was also decreased in gastrectomy subjects but this did not reach statistical significance (27.8+/-4 vs 21.9+/-3 pg/ml, P=0.3). Obestatin did not change significantly from baseline in response to the meal. Lean and obese subjects had a similar obestatin/ghrelin ratio (0.04+/-0.003 vs 0.05+/-0.009, P=0.32), but this was higher in the gastrectomy group (0.04+/-0.003 vs 0.1+/-0.01, P<0.001). CONCLUSIONS: Obestatin does not vary significantly with a fixed energy meal, but is significantly lower in morbidly obese subjects as compared to lean subjects supporting a possible role for obestatin in long-term body weight regulation. Obestatin tended to be lower in gastrectomy subjects and their obestatin/ghrelin ratio differed from healthy controls. Hence, the expression of obestatin is altered following gastrectomy, suggesting other sites outside the stomach may also secrete obestatin.