CEDIE   05498
CENTRO DE INVESTIGACIONES ENDOCRINOLOGICAS "DR. CESAR BERGADA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Overnight growth hormone (GH) concentrations are supressed by testosterone (T) infusion in eumenorrheic and polycystic ovary syndrome (PCOS) adolescents.
Autor/es:
ROPELATO MG; GARCIA RUDAZ MC; ESCOBAR ME; VELDHUIS JD; BARONTINI M
Lugar:
New York, N.Y., USA
Reunión:
Congreso; LWPES/ESPE 8TH JOINT MEETING; 2009
Institución organizadora:
LWPES/ESPE , APEG, APPES, JSPE and SLEP
Resumen:
Chronic exposure to gonadal steroids increases GH secretion. It has been demonstrated that lean PCOS patients have increased GH secretion. This study was aimed to explore acute effects of T on the characteristics of overnight GH profile in eumenorrheic and PCOS adolescents with normal BMI. Seven non obese PCOS adolescents and 8 matched controls (C) were studied in the early follicular phase of 3 consecutive menstrual cycles or in 3 consecutive months. Overnight GH profiles (1900 to 0700 h) were determined during saline (B) and constant testosterone (T) infusions, low dose (T-LD): 0.75 and high dose (T-HD): 2.5 mg/12 h iv. Blood samples were withdrawn every 20 minutes. GH (ICMA) and T (ECLIA) were determined during all 3 infusions. Pulsatile GH characteristics were analyzed by Cluster program. Results: On T-LD, T levels increased 2-3 folds from B in control group (1.4±0.25 to 4.1±0.46 nmol/L) and in PCOS (from 2.4±0.30 to 4.6±0.54 nmol/L), whereas on T-HD values rose to 8.5 ± 0.96 and to 10.4±0.67 nmol/L in C and in PCOS, respectively. None of the characteristics of GH release was modified by T-LD infusion in either C or PCOS. However, T-HD blunted mean GH concentrations (Control B: 2.0±0.41 vs T-HD: 1.4±0.26 ìg/L; PCOS: 2.7±0.54 vs 1.5±0.28 ìg/L), maximum GH peak height (Control B: 6.7±1.4 vs T-HD: 4.1±0.76 ìg/L; PCOS: 8.4±1.5 vs 5.2±0.81 ìg/L), and increment peak amplitude (Control B: 6.4±1.4 vs T-HD: 3.9±0.75 ìg/L; PCOS: 8.1±1.4 vs 5.0±0.80 ìg/L) (all parameters p<0.05 vs B). GH frequency did not change. Conclusions: Similar responses to acute T infusion in both groups suggest that the effect of T in GH system is maintained in PCOS. The selective decrease in GH pulse amplitude by T-HD in both groups of adolescents may reflect inhibition by nonestrogenic metabolites of T.