Effect of IGF-I administration on growth hormone secretion in obese subjects
2001
Tassone, F. | Gianotti, L. | Lanfranco, F. | Ganzaroli, C. | Oleandri, S.E. | Taliano, M. | Muller, E.E. | Ghigo, E. | Maccario, M.
OBJECTIVE: The reduction of spontaneous and stimulated growth hormone (GH) secretion in obesity could reflect an increase of the inhibitory effect of insulin growth factor I (IGF-I) on somatotroph secretion. DESIGN: In the present study we aimed to verify the effect of low dose recombinant human IGF-I (20 microgram/kg subcutaneously (s.c.) at 0 min) on 3 h-spontaneous GH secretion (mGHc, 0-180 min) and on the GH response to growth hormone releasing hormone (GHRH) (1 microgram/kg i.v. at+180 min) in obesity. SUBJECTS: Five obese women with abdominal adiposity (OB, age, mean+/-s.e.m.: 31+/-7.13 y; BMI: 32.04+/-3.69 kg/m2) and eight age-matched lean women (NW, 28.3+/-1.2 y; 20.1+/-0.5 kg/m2) were studied. RESULTS: The mGHc and GHRH-induced GH response in OB (1.0+/-0.7 microgram/l; AUC(180-270 min): 688.6+/-202.4 microgram/l min, respectively) were lower than in NW (2.6+/-0.8 microgram/l, 1315.9+/-189.9 microgram/l min, respectively, P < 0.05). The administration of rhIGF-I increased circulating IGF-I levels in OB and NW to the same extent (339.0+/-50.39 and 420.3+/-30.5 microgram/l, respectively). The rhIGF-I administration did not affect mGHc in OB or NW (1.1+/-0.9 and 3.2+/-1.0 microgram/l, respectively) but inhibited (P < 0.05) the GH response to GHRH in OB (324.2+/-153.1 microgram/l) and NW (730.2+/-288.1 microgram/l). CONCLUSIONS: Our study shows that the administration of low dose rhIGF-I reduces the somatotroph responsiveness to GHRH in obesity as well as in normal subjects.
显示更多 [+] 显示较少 [-]