Context: Little is known about the neuroendocrine effects of androgens on the GnRH-LH unit in females. Objective: Our objective was to evaluate androgen negative feedback on the GnRH-LH axis in eumenorrheic and polycystic ovary syndrome (PCOS) adolescents. Design and Setting:Weconducted a prospective, longitudinal, randomized, double-blind study at a pediatric endocrinology clinical research center. Participants: Seven nonobese PCOS adolescents and seven matched controls (C) were studied in the early follicular phase of three consecutive menstrual cycles or in three consecutive months. Intervention: Pulsatile LH release was determined during saline [baseline (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 drawn every 20 min overnight. Main Outcome Measures: LH (immunofluorometric assay) and T (electrochemiluminescence immunoassay) were determined at B, and during both T-LD and T-HD. LH profiles were analyzed by deconvolution and approximate entropy analyses. Results: On T-LD, C and PCOS serum T levels increased 2- to 3-fold vs. B. On T-HD, T values doubled in both groups vs. T-LD. Controls on T-LD had greater 12-h pulsatile LH secretion rate (P < 0.05 vs. B) and on T-HD had lower mean, pulsatile, basal LH release and LH approximate entropy (vs. B, P< 0.05). PCOS did not respond to T-LD. High-dose T did not alter mean LH in PCOS but increased pulsatile and reduced basal LH secretion. Conclusions: PCOS adolescents have impaired suppression of pulsatile LH secretion rate consistent with reduced androgen negative feedback. Attenuation of T feedback in nonobese adolescents with PCOS extends the pathophysiology of this syndrome.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical