[Lotus]

Ok, but it may not make much sense,

It's like deconstructing a model (call it a airplane model) that someone else built, only you're working in reverse to deconstruct right. Same applies here, you see a study that states 5 alpha reductase is reduced in the liver, now maybe this study was for cancer research or something similar. Let's take one of these studies,

Role of human type 3 3alpha-hydroxysteroid dehydrogenase (AKR1C2) in androgen metabolism of prostate cancer cells.

Aldo-keto reductases (AKRs) is another superfamily class of enzymes like the Cytochrome P450 enzyme super family, which are present in most tissues of the body, and play important roles in hormone synthesis and breakdown (including estrogen and testosterone synthesis and metabolism), cholesterol synthesis, and vitamin D metabolism. Cytochrome P450 enzymes also function to metabolize potentially toxic compounds, including drugs and products of endogenous metabolism such as bilirubin, principally in the liver.

AKRs are involved in the development and progression of many cancers, as well as chemotherapeutic drug resistance. AKR1B1 and AKR1B10 are overexpressed in tumors, such as liver, breast, and lung cancer. Several AKRs (AKR1A1, AKR1B10, and AKR1C1-3) are involved in tobacco-carcinogenesis, but they also catalyze the detoxication of nicotine derived nitrosamino ketones. In addition, AKR1C1-3 enzymes play a key role in the regulation of proliferative signaling in hormone dependent cancers.

So what they did in this study was to cut off the androgen synthesis to the receptors using another steroid , Four human aldo-keto reductases (AKRs) that belong to the AKR1C subfamily function in vitro as 3-keto-, 17-keto- and 20-ketosteroid reductases or as 3alpha-, 17beta- and 20alpha- hydroxysteroid oxidases to varying degrees. By acting as ketosteroid reductases or hydroxysteroid oxidases these AKRs can either convert potent sex hormones (androgens, estrogens and progestins) into their inactive metabolites or they can form potent hormones by catalyzing the reverse reaction. In this manner they may regulate occupancy and trans-activation of steroid hormone receptors.

In English, I want to find the link to activate AKR1c in the liver to shut off the androgen receptors therefore DHT never gets activated, simple right?.

Cha-Ching, found it.

Regulates access of 5alpha-DHT to the androgen receptor.

Abstract
Pairs of hydroxysteroid dehydrogenases (HSDs) govern ligand access to steroid receptors in target tissues and act as molecular switches. By acting as reductases or oxidases, HSDs convert potent ligands into their cognate inactive metabolites or vice versa. This pre-receptor regulation of steroid hormone action may have profound effects on hormonal response. We have identified the HSDs responsible for regulating ligand access to the androgen receptor (AR) in human prostate. Type 3 3alpha-hydroxysteroid dehydrogenase (aldo-keto reductase 1C2, aka-AKR acts solely as a reductase to convert 5alpha-dihydrotestosterone (DHT), a potent ligand for the AR (K(d)=10(-11)M for the AR), to the inactive androgen 3alpha-androstanediol (K(d)=10(-6)M for the AR); while RoDH like 3alpha-HSD (a short-chain dehydrogenase/reductase (SDR)) acts solely as an oxidase to convert 3alpha-androstanediol back to 5alpha-DHT. Our studies suggest that aldo-keto reductase (AKRs) and SDRs function as reductases and oxidases, respectively, to control ligand access to nuclear receptors.
http://www.ncbi.nlm.nih.gov/pubmed/17223255