THE EFFECTS OF CORTISOL ON THE REGULATION OF LIPOPROTEIN-LIPASE ACTIVITY IN HUMAN ADIPOSE-TISSUE

The influence of cortisol, in the presence of insulin, on the regulati on of lipoprotein lipase (LPL) activity was studied in human adipose t issue, using a tissue incubation technique. Tissue pieces were prein c ubated for 3 days in a control medium containing insulin (7175 pmol/L) , then incubated for 2 additional days in the control medium with and without cortisol (1000 nmol/L). After the 5 days of incubation, the le vels of LPL messenger ribonucleic acid (mRNA), relative LPL synthesis, and LPL activity (total and heparin releasable) were studied. Cortiso l exposure for 2 days increased all of the variables related to LPL. T he average increase was 2.5-fold for LPL mRNA, 3.0-fold for relative L PL synthesis, 5.2-fold for total LPL activity, and 9.4-fold for hepari n-releasable LPL activity compared to that in controls without cortiso l. The results confirm previous findings that cortisol, in the presenc e of insulin, has a marked stimulatory effect on LPL activity in human adipose tissue in vitro. New data have been presented on the mechanis ms of cortisol regulation of LPL activity. They involve both an increa sed level of LPL mRNA, leading to increased relative LPL synthesis, an d additional posttranslational regulation.