Topic
Pregnenolone
About: Pregnenolone is a research topic. Over the lifetime, 3539 publications have been published within this topic receiving 126444 citations. The topic is also known as: (3b)-3-hydroxy-Pregn-5-en-20-one & 3-Hydroxypregn-5-en-20-one.
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TL;DR: The expression and characterization of a human EST distinct from other human STs which sulfate estrogens indicates that this ST may be important in both the metabolism of estrogens and in the regulation of their activities.
212 citations
TL;DR: The isolation, cloning, and expression of a cDNA insert complementary to mRNA encoding human 3 beta-hydroxysteroid dehydrogenase/delta 5----4isomerase is reported, showing that the dehydrogenation/isomerization steps of steroid biosynthesis can be catalyzed by a single polypeptide chain, which can metabolize all of the major physiological substrates.
Abstract: The isolation, cloning, and expression of a cDNA insert complementary to mRNA encoding human 3β- hydroxysteroid dehydrogenase/δ5→4isomerase is reported. The insert contains an open reading frame encoding a protein of 372 amino acids, the initial 29 amino acids corresponding to the Nterminal sequence identified from the purified human placental microsomal enzyme. The cDNA was inserted into a modified pCMV vector and expressed in COS-1 monkey kidney tumor cells. The expressed protein was similar in size to human placental microsomal 3β-hydroxysteroid dehydrogenase/ Aδ5→4isomerase, as detected by immunoblot analysis, and catalyzed the conversion of 17α-hydroxypregnenolone to 17α-hydroxyprogesterone, pregnenolone to progesterone, and dehydroepiandro3- terone to androstenedione. Transfected COS cell homogenates, supplemented with NAD+, very efficiently oxidized 5α-androstan- 3β,17β-diol to 5α-dihydrotestosterone and, upon addition of NADH, reduced 5α-dihydrotestosterone to 5α-androstan- 3β,17β-diol. Thus, the ...
210 citations
TL;DR: Beta-sitosterol reduces the gonadal steroid biosynthetic capacity through effects on cholesterol availability or the activity of the side chain cleavage enzyme P450SCC, which could be a contributing factor to the reproductive dysfunction observed in fish exposed to BKME.
210 citations
207 citations
TL;DR: It is demonstrated that progesterone is not simply a sex steroid, and a new therapeutic approach is suggested to promote myelin repair in male mice after cryolesion of the sciatic nerve.
Abstract: Progesterone is shown here to be produced from pregnenolone by Schwann cells in peripheral nerves. After cryolesion of the sciatic nerve in male mice, axons regenerate and become myelinated. Blocking either the local synthesis or the receptor-mediated action of progesterone impaired remyelination. Administration of progesterone or its precursor, pregnenolone, to the lesion site increased the extent of myelin sheath formation. Myelination of axons was also increased when progesterone was added to cultures of rat dorsal root ganglia. These observations indicate a role for locally produced progesterone in myelination, demonstrate that progesterone is not simply a sex steroid, and suggest a new therapeutic approach to promote myelin repair.
206 citations