:Epipregnanolone

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| ImageFile = Epipregnanolone.svg

| ImageSize = 225px

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| IUPACName = 3β-Hydoxy-5β-pregnan-20-one

| SystematicName = 1-[(1S,3aS,3bR,5aR,7S,9aS,9bS,11aS)-7-Hydroxy-9a,11a-dimethylhexadecahydro-1H-cyclopenta[a]phenanthren-1-yl]ethan-1-one

| OtherNames = 3β,5β-Tetrahydroprogesterone

| Section1 = {{Chembox Identifiers

| CASNo = 128-21-2

| CASNo_Ref = {{cascite|correct|CAS}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 3KQ00893OL

| PubChem = 228491

| ChemSpiderID = 198867

| SMILES = CC(=O)[C@H]1CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2CC[C@H]4[C@@]3(CC[C@@H](C4)O)C)C

| StdInChI = 1S/C21H34O2/c1-13(22)17-6-7-18-16-5-4-14-12-15(23)8-10-20(14,2)19(16)9-11-21(17,18)3/h14-19,23H,4-12H2,1-3H3/t14-,15+,16+,17-,18+,19+,20+,21-/m1/s1

| StdInChIKey = AURFZBICLPNKBZ-GRWISUQFSA-N

}}

| Section2 = {{Chembox Properties

| C=21|H=34|O=2

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| Section3 = {{Chembox Hazards

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Epipregnanolone, also known as 3β-hydroxy-5β-pregnan-20-one, 3β,5β-tetrahydroprogesterone, or 3β,5β-THP, is an endogenous neurosteroid.{{cite book|title=Neurosteroids and Brain Function|url=https://books.google.com/books?id=BJumUEbiaPYC&pg=PR18|date=12 December 2001|publisher=Academic Press|isbn=978-0-08-054423-6|pages=18–}} It acts as a negative allosteric modulator of the GABA_A receptor and reverses the effects of potentiators like allopregnanolone.{{cite book|author=Abraham Weizman|title=Neuroactive Steroids in Brain Function, Behavior and Neuropsychiatric Disorders: Novel Strategies for Research and Treatment|url=https://books.google.com/books?id=uABKkFdPjhkC&pg=PA6|date=1 February 2008|publisher=Springer Science & Business Media|isbn=978-1-4020-6854-6|pages=6–}}{{cite book|author1=Jan Egebjerg|author2=Arne Schousboe|author3=Povl Krogsgaard-Larsen|title=Glutamate and GABA Receptors and Transporters: Structure, Function and Pharmacology|url=https://books.google.com/books?id=58-MfFUWutAC&pg=PA248|date=4 October 2001|publisher=CRC Press|isbn=978-0-7484-0881-8|pages=248–}} Epipregnanolone is biosynthesized from progesterone by the actions of 5β-reductase and 3β-hydroxysteroid dehydrogenase, with 5β-dihydroprogesterone as the intermediate in this two-step transformation.

Epipregnanolone is not a progestogen itself, but via metabolization into other steroids, behaves indirectly as one.{{cite journal|last1=Beyer|first1=C.|last2=González-Flores|first2=O.|last3=Ramı́rez-Orduña|first3=J.M.|last4=González-Mariscal|first4=G.|title=Indomethacin Inhibits Lordosis Induced by Ring A-Reduced Progestins: Possible Role of 3α-Oxoreduction in Progestin-Facilitated Lordosis|journal=Hormones and Behavior|volume=35|issue=1|year=1999|pages=1–8|issn=0018-506X|doi=10.1006/hbeh.1998.1457|pmid=10049597|s2cid=11520064 }}

The sulfate of epipreganolone, epipregnanolone sulfate, is a negative allosteric modulator of the NMDA{{cite book|author=Norman G. Bowery|title=Allosteric Receptor Modulation in Drug Targeting|url=https://books.google.com/books?id=WRfgvOKfZMcC&pg=PA112|date=19 June 2006|publisher=CRC Press|isbn=978-1-4200-1618-5|pages=112–}} and GABA_A receptors{{cite journal | vauthors = Park-Chung M, Malayev A, Purdy RH, Gibbs TT, Farb DH | title = Sulfated and unsulfated steroids modulate gamma-aminobutyric acidA receptor function through distinct sites | journal = Brain Res. | volume = 830 | issue = 1 | pages = 72–87 | year = 1999 | pmid = 10350561 | doi = 10.1016/s0006-8993(99)01381-5| s2cid = 44664830 | doi-access = free }} and also acts as a TRPM3 channel activator.{{cite book|title=Issues in Pharmacology, Pharmacy, Drug Research, and Drug Innovation: 2011 Edition|url=https://books.google.com/books?id=_sxCovKBJTkC&pg=PA3260|date=9 January 2012|publisher=ScholarlyEditions|isbn=978-1-4649-6342-1|pages=3260–}}{{cite book|title=Advances in Glutamic Acid Research and Application: 2013 Edition: ScholarlyBrief|url=https://books.google.com/books?id=8QLg8ZWOqs8C&pg=PA104|date=21 June 2013|publisher=ScholarlyEditions|isbn=978-1-4816-7049-4|pages=104–}}