Allopregnanolone, (3alpha-hydroxy-5alpha-pregnan-20-ol), also known as 3alpha,5alpha-tetrahydroprogesterone or THP, is a neuroactive steroid secreted by the mammalian ovary and adrenal.
It exerts its anesthetic, anxiolytic, and sedative/hypnotic effects through potentiation of GABA A receptors and its release is stimulated by trophic hormones in relation to stress and reproductive hormone secretion.