Allopregnanolone
![Skeletal formula of allopregnanolone](/Images/godic/202412/19/Allopregnanolone.svg0838.png")
![Ball-and-stick model of the allopregnanolone molecule](/Images/godic/202412/19/Allopregnanolone-3D-balls0838.png")
Allopregnanolone (3α-hydroxy-5α-pregnan-20-one or 3α,5α-tetrahydroprogesterone), generally abbreviated as ALLO or as 3α,5α-THP, is an endogenous inhibitory pregnane neurosteroid. It is synthesized from progesterone, and is a potent positive allosteric modulator of the action of gamma-amininobutyric acid (GABA) at GABAA receptor. Allopregnanolone has effects similar to those of other positive allosteric modulators of the GABA action at GABAA receptor such as the benzodiazepines, including anxiolytic, sedative, and anticonvulsant activity.