Isopregnanolone

Isopregnanolone, also known as isoallopregnanolone and epiallopregnanolone, as well as sepranolone (INN), and as 3β-hydoxy-5α-pregnan-20-one or 3β,5α-tetrahydroprogesterone (3β,5α-THP), is an endogenous neurosteroid and a natural 3β-epimer of allopregnanolone. It has been reported to act as a subunit-selective negative allosteric modulator of the GABA_A receptor, and antagonizes in animals and humans some but not all of the GABA_A receptor-mediated effects of allopregnanolone, such as anesthesia, sedation, and reduced saccadic eye movements, but not learning impairment. Isopregnanolone has no hormonal effects and appears to have no effect on the GABA_A receptor by itself; it selectively antagonizes allopregnanolone and does not affect the effects of other types of GABA_A receptor positive allosteric modulators such as benzodiazepines or barbiturates.