Allopregnanolone Levels Decrease after Gonadotropin Releasing Hormone Analogue Stimulation Test in Girls with Central Precocious Puberty.

Allopregnanolone (AP), neuroactive steroid secreted by brain, adrenals, and gonads, is a hormone that seems to play a role in the development of precocious puberty, as demonstrated by its high baseline levels found in girls with central precocious puberty (CPP). AP concentrations significantly increase after gonadotropin-releasing hormone (GnRH) and adrenocorticotropin hormone (ACTH) stimulation test suggesting both its ovarian and adrenal production. Aim of this study was to evaluate AP concentrations after GnRH and gonadotropin-releasing hormone agonist analogue (GnRHa) stimulation test in girls with CPP to better establish its secretion source. Gonodotropins and steroid hormones were evaluated in different days after GnRH and triptorelin (TRIP) stimulation test in 12 CPP girls. After GnRH stimulation luteinizing hormone (LH), follicle-stimulating hormone (FSH), and AP concentrations significantly increased (P < 0.05). After TRIP administration LH, FSH, estradiol and 17 hydroxy-progesterone levels significantly increased (P < 0.05), while AP concentrations significantly decreased (1.10 ± 0.26 vs. 0.89 ± 0.29 nmol/l; P = 0.001). The different response of AP to GnRH and GnRHa might reflect the agonist and antagonist action exerted by these secretagogues. Our data suggest the prevalent gonadal AP production in CPP subjects and the usefulness of its measurement in the diagnosis of CPP.