ACUTE CHANGES IN FREE-FATTY ACIDS (FFA) DO NOT ALTER SERUM LEPTIN LEVELS

Leptin, the product of the ob gene, is a recently discovered hormone s ecreted by adipocytes. Serum leptin concentrations increase in correla tion with the percentage of body fat, but besides that little is known about the physiological actions of leptin in humans. The aim of this study was to assess the influence of changes in circulating free-fatty acids on serum leptin levels. Increases in plasma FFA levels (p<0.02) were obtained in a group of normal subjects following the administrat ion of intralipid plus heparin (250 ml 10% Intralipid plus 5000 U hepa rin). FFA reduction was achieved through the administration of acipimo x (250 mg, orally, at 0 min and at 210 min), a lipid-lowering drug dev oid of side effects, to a group of normal (p<0.02) and obese subjects (p<0.05). An increase in circulating FFA levels in normal subjects (n= 6), following administration of a lipid-heparin infusion, failed to mo dify plasma leptin levels as assessed by the area under the curve (AUC ; mean+/-SE 892+/-168 for placebo vs 896+/-260 following intralipid pl us heparin). Similarly, whereas acipimox pretreatment induced a reduct ion in FFA levels compared to placebo in normal (n=6) and obese subjec ts (n=8), it also failed to modify plasma leptin levels at any time-po int studied. The results indicate that short-term reduction or increas e in circulating FFA are not associated to changes in plasma leptin le vels. (J. Endocrinol. invest. 27: 526-530, 1998) (C) 1998, Editrice Ku rtis.