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Effect of human growth hormone HGH on glycerol and free fatty acid metabolism during exhaustive exercise in GH-deficient adults.

Gibney J - J Clin Endocrinol Metab - 01-APR-2003; 88(4): 1792-7
NLM Citation ID:
12679475 (PubMed)
Full Source Title:
Journal of Clinical Endocrinology and Metabolism
Publication Type:
Clinical Trial; Journal Article; Randomized Controlled Trial
Author Affiliation:
Department of Diabetes and Endocrinology, Guys, Kings and St. Thomas' School of Medicine, St. Thomas Hospital, London SE1 7EH, United Kingdom.
Gibney J; Healy ML; Stolinski M; Bowes SB; Pentecost C; Breen L; McMillan C; Russell-Jones DL; Sonksen PH; Umpleby AM
GH is an important regulator of fat metabolism at rest, but it is not known whether it regulates fat metabolism during exercise. To determine whether physiologic concentrations of HGH influence fat metabolism during exercise, we randomized 16 HGH-deficient adults, receiving long-term (mean duration, 5 yr) HGH replacement, to either continue GH (n = 8) or receive identical placebo (n = 8) for a 3-month period. Metabolic studies, at rest, during and following exhaustive exercise were carried out at baseline and at the end of the 3 months. The rate of appearance of glycerol (glycerol Ra, an index of lipolysis) and free fatty acids (FFA, FFA Ra) and the rate of disappearance of FFA (FFA Rd) in the plasma were measured using infusions of (2)H(5)-glycerol and 1-(13)C-palmitic acid. Changes in body composition were assessed using dual-energy x-ray absorptiometry scanning and anthropometric measurements. In the baseline studies, exercise resulted in an increase in plasma glycerol and FFA concentrations, glycerol Ra, FFA Ra, and FFA Rd (P < 0.001). Three months of HGH withdrawal resulted in reductions in plasma glycerol and FFA, glycerol Ra, FFA Ra, and FFA Rd at rest (P < 0.05 vs. baseline) and during exercise (P < 0.05 vs. baseline and vs. GH treated). Lean body mass decreased after 3 months of HGH withdrawal, but total body fat, trunk fat, waist circumference, and the sum of skinfold thicknesses increased after 3 months of HGH withdrawal (P < 0.05 vs. baseline and vs. HGH treated). Fasting insulin and homeostasis model assessment of insulin resistance decreased after 3 months of HGH withdrawal (P < 0.05 vs. baseline and vs. GH treated). In summary, HGH withdrawal for 3 months resulted in reductions in release of glycerol and FFA into the circulation and uptake of FFA into the tissues during intense exercise. These changes were accompanied by reduced lean body mass and increased total body and trunk fat. Further studies are required to determine whether reduced mobilization of fat during exercise contributes to reduced exercise capacity and increased body fat in HGH-deficient adults.
Major Subjects:

Additional Subjects:

Chemical Compound Name:
(Carbon Isotopes); (Fatty Acids, Nonesterified); (Placebos); 11061-68-0(Insulin); 12629-01-5(Human Growth Hormone); 56-81-5(Glycerol); 67763-96-6(Insulin-Like Growth Factor I); 7782-39-0(Deuterium)

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