Remember these "on and off" switches?, part of this good news, the other part.....not so good.

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The good news....…


the reductase responsible for the conversion of estrone (a weak estrogen) to 17b-estradiol (a potent estrogen) is the estrogenic type 1 17b-HSD and is the `on' switch for the estrogen receptor (ER). The oxidase activities responsible for the reverse reaction and the inactivation of 17b-estradiol are the type 2 and type 4 17b-HSDs, and these function as the `off' switch for the ER.

Thus, the activity of these 17b-HSD isoforms may regulate the ligand occupancy of ERa and ERb and their trans- activation in estrogen target tissues (Wu et al., 1993; Andersson, 1995; Labrie et al., 1997; 2000).

Hydroxysteroid dehydrogenases and pre-receptor regulation of steroid hormone action http://humupd.oxfordjournals.org/content/9/3/193.full.pdf


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The not so good news.....

Phytoestrogens inhibit human 17b-hydroxysteroid dehydrogenase type 5
http://www.brc.dcs.gla.ac.uk/~rb106x/publications/HSD5Inhibition.pdf

(07-02-2015, 07:37 PM)Lotus Wrote: This is a bit over simplified but Hydroxysteroid Dehydrogenases (HSDs) act like a gate-keeper just before steroids (hormones) bind to receptors (synthesis). Furthermore, these "gate-keepers" can flip the switch (a light switch) on/off to allow passage to the cell receptors. So in essence, they can inhibit or promote hormone activity. Finding a new class of HSD's is the next step, Aldo-keto reductases (AKRs) can help us get there.