Growth hormone treatment of obese premenopausal women: Effects on isolated adipocyte metabolism

The effects of growth hormone (GH) administration on adipocyte metabolism in obese but otherwise healthy premenopausal women were investigated. Nine obese women (BMI = 34.5 ± 1.4 kg/m²) were treated with growth hormone (0.03 mg/kg IBW/day) for 5 weeks in a double blind placebo-controlled cross-over study. We have demonstrated previously that the women lost about 2 kg of adipose tissue during GH treatment. In the present study data on the adipose tissue metabolism will be described. Adipose tissue biopsies were taken from the subcutaneous abdominal and subcutaneous gluteal depot at the end of both placebo and GH treatment period. Basal as well as stimulated (epinephrine and isoproterenol) lipolysis were similar at the end of the two periods. The antilipolytic effect of insulin was similar in the two periods, however, both after placebo as well as after GH treatment the insulin sensitivity was higher in gluteal adipocytes compared to abdominal adipocytes (ED₅₀ in abdominal adipocytes was about 260 pm and 80 pm in gluteal adipocytes, P<0.05). In addition, the phosphodiesterase activity (PDE-activity) was two-fold higher in gluteal adipocytes compared to abdominal adipocytes, GH treatment had no effects on PDE activity. Growth hormone treatment was associated with decreased glucose oxidation in gluteal adipocytes both in the basal as well as in the insulin stimulated state. Furthermore, there was a tendency to decreased lipogenesis in both depots. Thus, our findings demonstate that GH treatment of obese women decreased glucose oxidation and tended to decrease lipogenesis. However, GH treatment seemed not to influence lipolysis or the antilipolytic activity of insulin. These findings suggest that the decrease in fat mass observed during GH treatment of obese women may be related to a decrease in uptake (reduced lipoprotein lipase activity) and probably a decrease in re-esterification of FFA and lipogenesis, with none or only minor alterations in lipolysis.