Pregnenolone

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Pregnenolone
Pregnenolone.svg
Pregnenolona3D.png
Systematic (IUPAC) name
3β-hydroxypregn-5-en-20-one
Clinical data
AHFS/Drugs.com International Drug Names
Routes of
administration
oral, transdermal
Legal status
Legal status
  • Commercially available
Identifiers
CAS Number 145-13-1 YesY
ATC code none
PubChem CID 8955
IUPHAR/BPS 2376
DrugBank DB02789 N
ChemSpider 8611 N
UNII 73R90F7MQ8 YesY
ChEBI CHEBI:16581 N
ChEMBL CHEMBL253363 N
Chemical data
Formula C21H32O2
Molar mass 316.483 g/mol
 NYesY (what is this?)  (verify)

Pregnenolone (3β-hydroxypregn-5-en-20-one), also known as P5, is an endogenous steroid hormone. It is the precursor of the progestogens, mineralocorticoids, glucocorticoids, androgens, and estrogens, as well as the neuroactive steroids. In addition, pregnenolone is biologically active in its own right, acting as a neurosteroid.[1]

Chemistry[edit]

Like other steroids, pregnenolone consists of four interconnected cyclic hydrocarbons. It contains ketone and hydroxyl functional groups, two methyl branches, and a double bond at C5, in the B cyclic hydrocarbon ring. Like many steroid hormones, it is hydrophobic. The sulfated derivative, pregnenolone sulfate, is water-soluble.

Biology[edit]

Biosynthesis[edit]

Pregnenolone is synthesized from cholesterol. This conversion involves hydroxylation at the side-chain at C20 and C22 positions, with cleavage of the side-chain. The enzyme performing this task is cytochrome P450scc, located in the mitochondria, and controlled by anterior pituitary tropic hormones, such as ACTH, FSH, LH.

To assay conversion of cholesterol to pregnenolone, radiolabelled cholesterol has been used.[2] Pregnenolone product can be separated from cholesterol substrate using Sephadex LH-20 minicolumns.[2]

Steroidogenesis, showing pregnenolone near top left.
Production of pregnenolone from cholesterol and further metabolism.
Reaction: pregnenolone → progesterone.

Prohormone activity[edit]

Pregnenolone undergoes further steroid metabolism in one of three ways.

Neurosteroid activity[edit]

Pregnenolone and its sulfate, like DHEA and its sulfate and progesterone, belong to the group of neurosteroids that are found in high concentrations in certain areas of the brain, and are synthesized there. Neurosteroids affect synaptic functioning, are neuroprotective, and enhance myelinization. Pregnenolone and its sulfate ester are under investigation for their potential to improve cognitive and memory functioning.[3] Pregnenolone is also being considered as a potential treatment for schizophrenia.[1]

Interestingly, unlike pregnenolone, pregnenolone sulfate is a negative allosteric modulator of the GABAA receptor[4] as well as a positive allosteric modulator of the NMDA receptor.[5][6] In addition, it has been shown to activate the transient receptor potential M3 (TRPM3) ion channel in hepatocytes and pancreatic islets causing calcium entry and subsequent insulin release.[7]

Pregnenolone, a molecule produced by the brain, is involved in a natural negative feedback loop against CB1 receptor activation in animals.[8] Pregnenolone prevents CB1 agonists like THC, the main active principle in cannabis, from fully activating the CB1 receptor, that when stimulated by THC causes the psychological effects of cannabis.

Additional images[edit]

References[edit]

  1. ^ a b Marx CE, Bradford DW, Hamer RM, et al. (September 2011). "Pregnenolone as a novel therapeutic candidate in schizophrenia: emerging preclinical and clinical evidence". Neuroscience. 191: 78–90. doi:10.1016/j.neuroscience.2011.06.076. PMID 21756978. 
  2. ^ a b Hanukoglu I, Jefcoate CR (1980). "Pregnenolone separation from cholesterol using Sephadex LH-20 mini-columns". Journal of Chromatography A. 190 (1): 256–262. doi:10.1016/S0021-9673(00)85545-4. 
  3. ^ Vallée M, Mayo W, Le Moal M (November 2001). "Role of pregnenolone, dehydroepiandrosterone and their sulfate esters on learning and memory in cognitive aging". Brain Research. Brain Research Reviews. 37 (1-3): 301–12. doi:10.1016/S0165-0173(01)00135-7. PMID 11744095. 
  4. ^ Majewska MD, Mienville JM, Vicini S (August 1988). "Neurosteroid pregnenolone sulfate antagonizes electrophysiological responses to GABA in neurons". Neuroscience Letters. 90 (3): 279–84. doi:10.1016/0304-3940(88)90202-9. PMID 3138576. 
  5. ^ Wu FS, Gibbs TT, Farb DH (September 1991). "Pregnenolone sulfate: a positive allosteric modulator at the N-methyl-D-aspartate receptor". Molecular Pharmacology. 40 (3): 333–6. PMID 1654510. 
  6. ^ Irwin RP, Maragakis NJ, Rogawski MA, Purdy RH, Farb DH, Paul SM (July 1992). "Pregnenolone sulfate augments NMDA receptor mediated increases in intracellular Ca2+ in cultured rat hippocampal neurons". Neurosci Lett. 141 (1): 30–4. doi:10.1016/0304-3940(92)90327-4. PMID 1387199. 
  7. ^ Wagner TF, Loch S, Lambert S, et al. (December 2008). "Transient receptor potential M3 channels are ionotropic steroid receptors in pancreatic beta cells". Nature Cell Biology. 10 (12): 1421–30. doi:10.1038/ncb1801. PMID 18978782. 
  8. ^ http://www.sciencedaily.com/releases/2014/01/140102142012.htm