J Korean Soc Study Obes 2000; 9(2): 112-121
Published online July 1, 2000
Copyright © Korean Society for the Study of Obesity.
Su Youn Nam,Ju Ik Son,Kyung Wook Kim,Uh IL Park,Jun Uh Kim,Woon Hyoung Park,Seung Baik Yun,Kyung Rae Kim,Kee Seup Song,Young Duk Song,Sung Kil Lim,Hyun Chul Lee,Kap Bum Huh
Division of endocrinology, Department of Internal Medicine, Yonsei University Medical College, Seoul, Korea
Background: Growth hormone (GH) can play a possible therapeutic role in obesity by accelerating lipolysis and exerting an anabolic effect. Considering that the serum GH-binding protein (GHBP) level may reflect the GH receptor, the elevated levels of GHBP in obesity may indicate up-regulation of the GH receptor and increase GH sensitivity. Serum GHBP level is associated with body fat amount. It is not certain how GHBP level can be changed by GH treatment with diet restriction in obese subjects.
Methods: we measured serum GHBP, insulin and free fatty acid (FFA) during oral glucose tolerance (OGTT) and IGF-I level as well as visceral and subcutaneous adipose tissue (AT) areas by using CT scan in 18 obese subjects and in 9 age-matched healthy lean subjects. The 18 obese subjects were treated with GH (n=9, 0.03 IU/kg IBW/day) or placebo (n=9, vehicle injection) for 12 weeks and were fed a diet of 25 kcal/kg IBW/day.
Results: 1. The GHBP levels were elevated in obese subjects compared to lean controls and were similar in both obese groups before treatment (GH, 2.24±0.51; placebo, 2.22±0.27; control, 1.04±0.20 ng/mL).
2. After 12 week-treatment, the loss of BW was not different in both groups (GH, 6.01±2.14; placebo, 5.47±3.56 kg). The fraction of BW loss as fat loss was significantly greater (1.20±0.51 vs 0.65±0.44 kg/kg, p<0.05) and visceral fat was decreased more in GH group than in placebo group (27.9% vs 21.6%, p<0.05). After 12 week treatment, GHBP level in GH group was significantly decreased but not to the level of normal control (GH, 1.55±0.41 vs control, 1.04±0.20 ng/mL, p<0.05) whereas GHBP level in placebo group tended to decrease after treatment, but did not reach significance (2.22±0.27 vs 1.91±0.39 ng/mL).
3. The treatment-induced changes in GHBP levels were positively correlated with decreases in total body fat, visceral AT area and FFA-area under the curve(AUC). No correlation was found between changes in GHBP level and changes in IGF-I and insulin-AUC.
4. Multiple stepwise regression analysis revealed that changes in visceral AT area and total body fat amount after treatment were accounted for 64% of fall in GHBP levels.
Conclusion: Increased GHBP levels in obesity are reversible weight loss resulting from low-dose GH treatment and diet restriction. GH exposure does not substantially regulate GHBP levels but the decrease in visceral fat amount mainly related to the changes in GHBP level.
Keywords: GHBP, Visceral fat, GH treatment, Obesity