Steroid biosynthesis

About: Steroid biosynthesis is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 58977 citations.

Effect of oestradiol in adrenal corticoidogenesis: an additional step in steroid biosynthesis.

Abstract: OOPHORECTOMY in the albino rat results in diminished pituitary adrenocorticotrophic hormone (ACTH) secretion and in diminished adrenal secretion of corticosterone1. The latter is demonstrable in peripheral plasma after injection of ACTH or following stress, in adrenal venous effluent, and in adrenal slices incubated in vitro. Administration of oestradiol-17β reverses these effects. Although the adrenal response to oestradiol may, in part, be mediated by changes in ACTH secretion, a direct effect is also suggested by the finding that oestradiol stimulates corticosteroid production when added to adrenal slices in vitro2, and when administered to hypophysectomized, oophorectomized rats in vivo3. Additional investigations suggest an apparent inhibition of steroidogenesis in adrenal tissue after oophorectomy4. This communication reports observations giving a more specific definition of the relation of the ovary to adrenal function.

Beta-Hydroxysteroid Dehydrogenase Genes in Orange-Spotted Grouper (Epinephelus coioides): Genome-Wide Identification and Expression Analysis During Sex Reversal.

Abstract: Beta-hydroxysteroid dehydrogenases (β-HSDs) are a group of steroidogenic enzymes that are involved in steroid biosynthesis and metabolism, and play a crucial role in mammalian physiology and development, including sex determination and differentiation. In the present study, a genome-wide analysis identified the numbers of β-hsd genes in orange-spotted grouper (Epinephelus coioides) (19), human (Homo sapiens) (22), mouse (Mus musculus) (24), chicken (Gallus gallus) (16), xenopus (Xenopus tropicalis) (24), coelacanth (Latimeria chalumnae) (17), spotted gar (Lepisosteus oculatus) (14), zebrafish (Danio rerio) (19), fugu (Takifugu rubripes) (19), tilapia (Oreochromis niloticus) (19), medaka (Oryzias latipes) (19), stickleback (Gasterosteus aculeatus) (17) and common carp (Cyprinus carpio) (27) samples. A comparative analysis revealed that the number of β-hsd genes in teleost fish was no greater than in tetrapods due to gene loss followed by a teleost-specific whole-genome duplication event. Based on transcriptome data from grouper brain and gonad samples during sex reversal, six β-hsd genes had relatively high expression levels in the brain, indicating that these genes may be required for neurogenesis or the maintenance of specific biological processes in the brain. In the gonad, two and eight β-hsd genes were up- and downregulated, respectively, indicating their important roles in sex reversal. Our results demonstrated that β-hsd genes may be involved in the sex reversal of grouper by regulating the synthesis and metabolism of sex steroid hormones.

Regulation of 3β-HSD activity in the songbird brain

Abstract: Birds show high levels of steroid synthesis in the brain. Steroid biosynthesis in the brain can provide a mechanism for local and rapid changes in steroid levels in particular brain regions. Neural steroidogenic enzymes are regulated on both short and long timescales by both endogenous and environmental factors. Here, we discuss the regulation of one steroidogenic enzyme, 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3β-HSD), which activates the prohormone dehydroepiandrosterone by converting it to a potent and aromatizable androgen, androstenedione. First, brain 3β-HSD mRNA and activity are regulated by developmental stage in nestling Zebra Finches (Taeniopygia guttata). Second, in vitro estradiol rapidly (<10 min) inhibits Zebra Finch brain 3β-HSD activity. Third, restraint stress rapidly (<15 min) regulates brain 3β-HSD activity in adult Zebra Finches and Song Sparrows (Melospiza melodia). Fourth, brain 3β-HSD activity is upregulated during the non-breeding season in wild male Song Sparrows. Fifth, during the non-breeding season, brain 3β-HSD activity is rapidly (<30 min) elevated by territorial encounters in a region-specific manner in male Song Sparrows. Taken together, these studies suggest that brain 3β-HSD is a key factor in the control of avian neurophysiology and behavior.

Effects of different steroid-biosynthesis inhibitors on the testicular steroidogenesis of the toad Bufo arenarum.

Abstract: Testis fragments from Bufo arenarum were incubated with [7(n)-3H]pregnenolone (P5), [1,2-3H]dehydroepiandrosterone (DHEA) and [1,2,6,7-3H]testosterone (T), and different steroid-biosynthesis inhibitors. The inhibitors used were: cyanoketone (CNK), spironolactone (SPNL) and finasteride (FIN). CNK significantly increased the recovery of 3β-hydroxy-5-ene steroids while SPNL reduced the metabolism of P5 and the production of C19-steroids. The metabolism of C19-substrates was only modified by CNK, which reduced the transformation of DHEA without modifying the metabolism of T. To determine the degree of inhibition exerted by the inhibitors used, the activities of the enzymes were estimated as the percentage of their contribution to the total steroid metabolism. CNK strongly inhibited the activity of hydroxysteroid dehydrogenase/isomerase if its contribution was estimated using both P5 and DHEA. If the analysis was made considering both activities associated to cytochrome P450 17α-hydroxylase, C17–20 lyase (P450c17), it became evident that SPNL inhibited both of them. The percent contribution of 17β-hydroxysteroid dehydrogenase (17βHSD) activity diminished in the presence of CNK only if it was estimated considering P5 and DHEA metabolism. SPNL produced a significant inhibition of 17βHSD when its contribution was estimated considering P5 metabolism. However, SPNL was insufficient if DHEA or T were considered. The effect of SPNL on the contribution of 17βHSD could be due to the reduction of C19-substrates. The activity of 5α-reductase was inhibited by CNK only if results from P5 and DHEA were considered.