Acute infusion of naloxone, an opioid receptor antagonist, does not modify serum leptin concentrations in amenorrheic and healthy women

Objective: To determine whether the opioidergic system is involved in the modulation of leptin secretion in healthy and amenorrheic subjects. Design: Prospective study. Setting: Department of Obstetrics and Gynecology, University of Modena, Modena, Italy. Patient(s): Healthy subjects (n = 8) and patients with hypothalamic amenorrhea (n = 17) or hyperandrogenism (n = 7) and low body mass index (BMI). Intervention(s): Acute infusion of naloxone (4-mg bolus) and blood sampling 15 minutes before infusion; at time of infusion; and 15, 30, 45, 60, 75, 90, and 120 minutes after infusion. Main Outcome Measure(s): Plasma leptin, LH, FSH, E2, and cortisol concentrations. Result(s): Plasma leptin concentrations were lower (P <.01) in both hypothalamic and hyperandrogenic amenorrheic subjects than in healthy controls. In all groups of subjects, no significant changes in leptin levels were observed after infusion of naloxone. A significant correlation was found between leptin concentrations and BMI when all subjects were considered together (P <.05) but was not found in the single groups. Conclusion(s): The present data do not support the hypothesis that opioidergic receptors are involved acutely in the modulation of leptin release in healthy and amenorrheic women.