17-Hydroxypregnenolone 5324737 160531579 2007-09-26T19:24:06Z 58.0.247.205 {{drugbox | | IUPAC_name = 3β,17-dihydroxypregn-5-en-20-one | image = 17-Hydroxypregnenolone.png | CAS_number = 387-79-1 | ATC_prefix = | ATC_suffix = | PubChem = 3032570 | DrugBank = | C = 21 | H = 32 | O = 3 | molecular_weight = 332.48 g/mol | bioavailability = | protein_bound = | metabolism = [[Adrenal]][[Gonad]]s | elimination_half-life = | excretion = | pregnancy_AU = <!-- A / B1 / B2 / B3 / C / D / X --> | pregnancy_US = <!-- A / B / C / D / X --> | pregnancy_category = | legal_AU = <!-- Unscheduled / S2 / S3 / S4 / S8 --> | legal_UK = <!-- GSL / P / POM / CD --> | legal_US = <!-- OTC / Rx-only --> | legal_status = | routes_of_administration = | melting_point = 268 }} '''17-Hydroxypregnenolone''' (also '''17-OH-pregnenolone''' and '''17α-hydroxypregnenolone'''), is a C21 [[steroid]] that is obtained by [[hydroxylation]] of [[pregnenolone]] at the C17α position. This step is performed by the [[mitochondria]]l [[cytochrome P450 oxidase|cytochrome P450 enzyme]] 17α-hydroxylase ([[CYP17A1]]) that is present in the [[adrenal]] and [[gonad]]s. Peak levels are reached in humans at the end of [[puberty]] and then decline.<ref>Hill M, Lukac D, Lapcik O, Sulcova J, Hampl R, Pouzar V, Starka L. Age relationships and sex differences in serum levels of pregnenolone and 17-hydroxypregnenolone in healthy subjects. Clin Chem Lab Med. 1999 Apr;37(4):439-47. PMID 10369116</ref> High levels are also achieved during [[pregnancy]]. ==Prohormone== [[Image:DHEA1.svg|thumb|right|350px|17 OH–pregnenolone is converted from pregnenolone and gives rise to DHEA (below) and to 17 OH-progesterone (to its right)]] 17-OH-pregnenolone is considered a [[prohormone]] in the formation of [[dehydroepiandrosterone]] (DHEA), itself a prohomone of the [[sex steroid]]s. This conversion is mediated by the enzyme 17,20 lyase . As such 17-OH-pregenolone represents an intermediary in the delta-5-pathway that leads from pregnenolone to DHEA. 17-hydroxypregneolone is also converted to [[17-hydroxyprogesterone]], a prohomone for [[glucocorticosteroid]]s and [[androstenedione]] through the activity of 3-hydroxysteroid dehydrogenase. ==Neurohormone== There is some evidence that 17-OH-pregnenolone may have activity as a [[neurohormone]].<ref>Matsunaga M, Ukena K, Baulieu EE, Tsutsui K 7alpha-Hydroxypregnenolone acts as a neuronal activator to stimulate locomotor activity of breeding newts by means of the dopaminergic system. Proc Natl Acad Sci USA 2004 Dec 7;101(49):17282-7. PMID 15569930</ref> ==Clinical use== Measurements of 17-OH-pregnenolone are useful in the diagnosis of certain forms of [[congenital adrenal hyperplasia]].<ref>Riepe FG, Mahler P, Sippell, Partsch CJ. Longitudinal Study of Plasma Pregnenolone and 17-Hydroxypregnenolone in Full-Term and Preterm Neonates at Birth and during the Early Neonatal Period. The Journal of Clinical Endocrinology & Metabolism (2002) 87: 4301-4306 [http://jcem.endojournals.org/cgi/content/full/87/9/4301]</ref> In patients with [[congenital adrenal hyperplasia due to 3 beta-hydroxysteroid dehydrogenase deficiency]] 17-OH-pregnenolone is increased, while in patients with [[congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency]] levels are low to absent. ==See also== [[Congenital adrenal hyperplasia]] ==Additional images== <gallery> Image:Steroidogenesis.gif|[[Steroidogenesis]] </gallery> ==References== {{reflist}} [[Category:Steroids|Hydroxypregnenolone, 17-]] [[ja:17-ヒドロキシプレグネノロン]]