DEPOT-SPECIFIC AND SEX-SPECIFIC DIFFERENCES IN HUMAN LEPTIN MESSENGER-RNA EXPRESSION - IMPLICATIONS FOR THE CONTROL OF REGIONAL FAT DISTRIBUTION

Obese subjects with excess intra-abdominal fat deposition suffer great er adverse metabolic consequences than do similarly overweight subject s with a predominantly subcutaneous distribution of adiposity. Little is known about the factors regulating the regional distribution of bod y fat. Leptin is a recently characterized protein secreted by adipocyt es that appears to provide a long-term hormonal feedback signal regula ting fat mass. No systematic evaluation of site-related differences in human adipocyte leptin expression has been reported to date. Levels o f leptin mRNA were examined by quantitative reverse transcription-poly merase chain reaction in adipocytes isolated from omental and subcutan eous adipose depots of nonobese and mildly obese individuals undergoin g elective surgery. In all individuals studied (n = 24), leptin mRNA l evels were higher in subcutaneous than in omental adipocytes (P < 0.00 01). In contrast, there were no consistent site-specific differences i n the expression of glycerol-3-phosphate dehydrogenase mRNA. The subcu taneous-to-omental ratio of leptin mRNA expression was markedly higher in women (5.5 +/- 1.1-fold) than in men (1.9 +/- 0.2-fold) (P < 0.02) . A significant relationship between BMI and leptin mRNA expression wa s demonstrable in the subcutaneous adipocytes of women (P < 0.006). Th us, leptin mRNA appears to be expressed predominantly by subcutaneous adipocytes, particularly in women. These findings suggest a possible r ole for leptin in the control of adipose tissue distribution and mass.