Effects of growth hormone treatment on the leptin system and body composition in obese prepubertal boys

Leptin correlates with measures of body fat stares. Growth hormone (GH) tre atment may affect leptin levels either directly or indirectly by influencin g body composition and circulating insulin level. Here, the effects Of GH t reatment on the leptin axis and body composition of six severely obese, but otherwise healthy, prepubertal boys were studied. Fasting serum leptin was significantly reduced after only 3wk of GH treatment. Body fat percentage, but not BMI, decreased significantly (p < 0.05) after 3 mo. The serum lept in concentration per unit fat mass decreased significantly during GH treatm ent (p < 0.05), suggesting that such treatment might have a direct effect o n serum leptin independently of the effects on body composition. Leptin RNA expression in abdominal subcutaneous tissue was not significantly changed by treatment. Conclusions: The data indicate that GH has an early downregulatory effect o n the circulating leptin level independently of the concomitant changes in body composition. Whether GH affects leptin production or metabolism needs further study.