EFFECTS OF GROWTH-HORMONE TREATMENT ON THE LEPTIN SYSTEM AND ON ENERGY-EXPENDITURE IN ABDOMINALLY OBESE MEN

The present study has examined the short-and long-term effects of grow th hormone (GH) treatment on the leptin system and energy expenditure. Thirty male individuals with abdominal obesity were randomised to GH or placebo treatment in a 9-month, double-blind study. The dose of GH was 9.5 mu g/kg, administered subcutaneously every evening. Serum lept in concentrations were measured by a human leptin RIA. Total RNA was i solated from adipose tissue biopsies and leptin mRNA levels were deter mined by a semi-quantitative reverse transcriptase-PCR assay, Body com position was determined by potassium-40 and the basal metabolic rate ( BMR) was measured by a computerised. ventilated, open-hood system. As compared with placebo, an overall decrease in serum leptin concentrati ons as assessed by the area under the curve (AUC) (P < 0.05) and an in crease in BMR (AUC, P < 0.05) were observed during GH treatment. The o verall GH-induced changes were due to marked changes in serum leptin c oncentrations and BMR after 6 weeks of treatment. After 9 months of GH treatment there was a significant reduction in body fat (BF) while se rum leptin concentrations and BMR did not differ from baseline values. Leptin mRNA levels did not change over the study period. We speculate that long-term GH treatment induces a new energy balance steady state with decreased BF stores. The effects of GH on the leptin system is s uggested to be of importance for the maintenance of a lower BF mass.