Androsterone, or 3α-hydroxy-5α-androstan-17-one, is an endogenous steroid hormone, neurosteroid, and putative pheromone. It is a weak androgen with a potency that is approximately 1/7 that of testosterone. Androsterone is a metabolite of testosterone and dihydrotestosterone (DHT). In addition, it can be converted back into DHT via 3α-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase, bypassing conventional intermediates such as androstanedione and testosterone, and as such, can be considered to be a metabolic intermediate in its own right.

Androsterone is also known to be an inhibitory androstane neurosteroid, acting as a positive allosteric modulator of the GABA<sub>A</sub> receptor, and possesses anticonvulsant effects. The unnatural enantiomer of androsterone is more potent as a positive allosteric modulator of GABA<sub>A</sub> receptors and as an anticonvulsant than the natural form. Androsterone's 3β-isomer is epiandrosterone, and its 5β-epimer is etiocholanolone. The 3β,5β-isomer is epietiocholanolone.

Biological function

Androsterone has generally been considered to be an inactive metabolite of testosterone, which when conjugated by glucuronidation and sulfation allows testosterone to be removed from the body, but it is a weak neurosteroid that can cross into the brain and could have effects on brain function. Androstanediol, a metabolite of androsterone, can be used a marker of the backdoor pathway of DHT synthesis. Spectrometric studies identify androsterone as the main backdoor androgen in the human male fetus. Circulating levels are sex dependent, DHT being essentially absent in the female, in which titres of backdoor intermediates also are very low.

Pheromone

Androsterone is found in the human axilla and skin as well as in the urine. It may also be secreted by human sebaceous glands.

History

Androsterone was first isolated in 1931, by NSDAP-Member Adolf Friedrich Johann Butenandt and Kurt Tscherning. They distilled over of male urine, from which they got of crystalline androsterone, which was sufficient to find that the chemical formula was very similar to estrone. They collected the urine of male prisoners on the premises of various Berlin police stations.

See also

  • Androgen backdoor pathway
  • List of androgens/anabolic steroids
  • List of neurosteroids § Androstanes
  • List of neurosteroids § Pheromones and pherines
  • 3α-Hydroxysteroid dehydrogenase

References

  • Androsterone entry in the HMDB