Allopregnanolone levels decrease after gonadotropin-releasing hormone analog stimulation test in girls with central precocious puberty

Abstract

Allopregnanolone, a neuroactive steroid mainly secreted by adrenals and gonads, is a hormone that seems to play a role in precocious puberty, as demonstrated by its high baseline levels found in girls with central precocious puberty (CPP). Allopregnanolone concentrations significantly increase after GnRH and ACTH stimulation test suggesting both its ovarian and adrenal production. Aim of this study was to evaluate allopregnanolone concentrations after GnRH and GnRH agonist analog stimulation test in girls with CPP to better establish its secretion source. Gonadotropins and steroid hormones were evaluated in different days after GnRH and triptorelin stimulation test in 15 CPP girls. After GnRH stimulation, LH, FSH, and allopregnanolone concentrations significantly increased (p<0.05). After triptorelin administration LH, FSH, estradiol and DHEAS levels significantly increased (p<0.05), while allopregnanolone concentrations significantly decreased (1.08±0.24 vs 0.87±0.28 nmol/l; p=0.003). The different response of allopregnanolone to GnRH and GnRH agonist analog might reflect the agonist and antagonist action exerted by these secretagogues. Our data suggest the prevalent gonadal allopregnanolone production in CPP subjects and the usefulness of its measurement in the diagnosis of CPP.