Increases in leptin levels, sympathetic drive, and weight gain in obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) are frequently obese and are pr edisposed to weight gain. They also have heightened sympathetic drive. We r easoned that noradrenergic activation of beta(3)-receptors on adipocytes wo uld inhibit leptin production, predisposing to obesity in sleep apnea. We t herefore tested the hypothesis that obesity and predisposition to weight ga in in OSA are associated with low levels of plasma leptin. We prospectively studied 32 male patients (43 +/- 2 yr) with OSA who were newly diagnosed a nd never treated and who were free of any other diseases. Control measureme nts were obtained from 32 similarly obese closely matched male subjects (38 +/- 2 yr). Leptin levels were 13.7 +/- 1.3 and 9.2 +/- 1.2 ng/ml in patien ts with OSA and controls, respectively (P = 0.02). Weight gain over the yea r before diagnosis was 5.2 +/- 1.7 and 0.5 +/- 0.9 kg in sleep apnea patien ts and similarly obese control subjects, respectively (P = 0.04). Muscle sy mpathetic activity was 46 +/- 4 and 30 +/- 4 bursts/min in patients with OS A (n = 16) and control subjects (n = 18), respectively (P = 0.01). Plasma l eptin levels are elevated in newly diagnosed otherwise healthy patients wit h untreated sleep apnea beyond the levels seen in similarly obese control s ubjects without sleep apnea. Higher leptin levels in OSA, independent of bo dy fat content, suggest that OSA is associated with resistance to the weigh t-reducing effects of leptin.