THE EXPRESSION OF OB GENE IS NOT ACUTELY REGULATED BY INSULIN AND FASTING IN HUMAN ABDOMINAL SUBCUTANEOUS ADIPOSE-TISSUE

The regulation of ob gene expression in abdominal subcutaneous adipose tissue was investigated using a reverse transcription-competitive PCR method to quantify the mRNA level of leptin. Leptin mRNA level was hi ghly correlated with the body mass index of 26 subjects (12 lean, 7 no n-insulin-dependent diabetic, and 7 obese patients). The effect of fas ting on ob gene expression was investigated in 10 subjects maintained on a hypocaloric diet (1045 KJ/d) for 5 d. While their metabolic param eters significantly changed (decrease in insulinemia, glycemia, and re sting metabolic rate and increase in plasma ketone bodies), the calori c restriction did not modify the leptin mRNA level in the adipose tiss ue. To verify whether insulin regulates ob gene expression, six lean s ubjects underwent a 3-h euglycemic hyperinsulinemic (846+/-138 pmol/li ter) clamp. Leptin and Glut 4 mRNA levels were quantified in adipose t issue biopsies taken before and at the end of the clamp. Insulin infus ion produced a significant threefold increase in Glut 4 mRNA while lep tin mRNA was not affected. It is concluded that ob gene expression is not acutely regulated by insulin or by metabolic factors related to fa sting in human abdominal subcutaneous adipose tissue.