|Jmol-3D images||Image 1|
|Molar mass||318.49 g/mol|
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C or 77 °F, 100 kPa)
Allopregnanolone (3α-hydroxy-5α-pregnan-20-one or 3α,5α-tetrahydroprogesterone; also abbreviated as THP or THPROG) is a prototypic neurosteroid present in the blood and also the brain. It is a metabolite of progesterone and potent modulator of GABAA receptors. While allopregnanolone, like other GABAA receptor active neuro steroids such as allotetrahydrodeoxycorticosterone (3α,21-dihydroxy-5α-pregnan-20-one; THDOC), positively modulates all GABAA receptor isoforms, those isoforms containing δ-subunits exhibit greater magnitude potentiation. Allopregnanolone has pharmacological properties similar to other positive modulators of GABAA receptors, including anxiolytic and anticonvulsant activity.
The biosynthesis of allopregnanolone starts with the converting of progesterone into 5α-dihydroprogesterone by 5α-reductase type I. After that, 3α-hydroxysteroid oxidoreductase isoenzymes (also referred to as 3α-hydroxysteroid dehydrogenase) converts this intermediate into allopregnanolone. Anxiety and depression are common side effects of 5α-reductase inhibitors such as finasteride and dutasteride, and they are believed to be caused, in part, by the prevention of the endogenous production of allopregnanolone.
The 5β-epimer of this compound (pregnanolone; 3α-hydroxy-5β-pregnan-20-one) has similar properties to allopregnanolone, and the 3β-methyl analogue, ganaxolone, is under development to treat epilepsy and other conditions.
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