T Nation

Androgen Receptor--Function/Mode of Action

For anyone interested in the function of the androgen receptor. You so rarely get “regular”, solid science to base conclusions and hypotheses on in the AAS using crowd, I figured this might be useful for us warrior-geeks.

I’m posting the full text of the article right below. It is a review article on the AR. This is NOT bite-sized. It’s fairly comprehensive (doesn’t cover all aspects of signaling). AND LONG. Grad level biochemistry at it’s best. But I’m pretty sure you all are intelligent enough to handle it and get something useful out of it.

It covers the AR in conjunction with environmental estrogens/androgens, etc.

You can download the pdf of it for free by googling the article title.

Pure Appl. Chem., Vol. 75, Nos. 11�??12, pp. 1685�??1697, 2003.
© 2003 IUPAC
1685

[u]Biological function and mode of action of the
androgen receptor*
[/u]

Elizabeth M. Wilson
Laboratories for Reproductive Biology, and the Department of Pediatrics and the
Department of Biochemistry and Biophysics, University of North Carolina, Chapel
Hill, NC 27599, USA

Abstract: Chemical contaminants with antiandrogen or androgen activity have been identified in the environment. The mode of action of these endocrine disruptors derives from their ability to bind to the androgen receptor (AR), a member of the steroid receptor family of nuclear receptors.

The AR is a ligand-activated transcription factor with properties unique among members of the steroid receptor family. Binding of endocrine disruptors to the AR impacts
its ability to activate or inhibit AR-regulated genes.

Most notable of these are the agonist-
induced and antagonist-inhibited interdomain interactions that influence AR stability
and function. Environmental antiandrogens identified thus far are metabolites of pesticides and herbicides, exerting androgen antagonist effects by blocking AR-induced gene transcription required for male sexual development.

Environmental androgens can be precursors
of the naturally occurring biologically active androgens testosterone and dihydrotestosterone
or result from anabolic steroid use in the livestock industry. They have agonist activity by their ability to bind the AR and mimic the natural hormone, increasing AR-mediated transcription of androgen-responsive genes.

The presence of masculinized female fish in polluted rivers indicates the presence of androgen-like pollutants in the environment.

STRUCTURAL AND FUNCTIONAL PROPERTIES OF THE ANDROGEN RECEPTOR

Domain structure of the androgen receptor

The androgen receptor (AR) is encoded by a single gene on the X chromosome at Xq11-12 [1,2]. The AR consists of 919 amino acid residues [3] and occurs as a single form in mammalian cells. The precise amino residue length of the AR can vary, however, due to the presence of polymorphic amino acid
repeats.

In contrast, most other steroid receptors are coded by more than one gene and are expressed in
multiple forms. Previous reports of A and B forms of the AR appear to result from proteolytic breakdown during tissue preparation [4]. AR is sensitive to degradation during its isolation, and in some cases
is not protected from degradation by the addition of protease inhibitors [5].

AR degradation is minimized by the binding of high-affinity androgens [6]. The overall structural arrangement of the AR is
similar to other steroid receptors with several relatively autonomous domains contributing a specific function.

These include the NH2-terminal region, the DNA-binding domain, and the carboxyl-terminal
ligand-binding domain.

NH2-terminal region

The AR NH2-terminal region is comprised of 558 amino acid residues and contains the major transactivation domain [7] referred to as activation function 1 (AF1).

This is a poorly defined region that lies
within amino acid residues 142�??337 [8]. AF1 appears to be the predominant activation region in AR and depends on androgen binding for activation [7].

The NH2-terminal region contains in addition several amino acid repeat sequences, the most notable being the CAG trinucleotide repeat that codes for a stretch of glutamine residues.

The NH2-terminal region also contains a glycine repeat that has a more constant length of about 23 residues. The function of the glutamine and glycine repeat in AR activity is not known. The CAG repeat region coding for polyglutamine is polymorphic in the normal population.

Shorter CAG repeat lengths have an increased
association with prostate cancer [9]. The AR CAG repeat length is relatively invariant even in its expanded form [10] and has been used as a marker in human population genetics.

CAG repeat expansion to more than 40 glutamine residues results in Kennedy�??s disease or adult onset spinal bulbar muscular atrophy [11].

While the direct relationship between glutamine repeat length and Kennedy�??s disease is not understood, the expanded CAG repeat is associated with decreased expression of the AR messenger RNA, resulting in reduced AR protein levels in transfection assays [12].

Trinucleotide repeat
expansions in other genes are associated with neurological diseases such as Huntington�??s disease, the
fragile X syndrome, and myotonic dystrophy, where repeat sequences occur in coding or noncoding regions depending on the gene [9].

The AR CAG trinucleotide repeat length has undergone an exponential increase through evolution of the primates back to the lemur [13]. The rat AR sequence has a short
glutamine repeat at the position of the human AR CAG repeat, but remarkably, has a CAG repeat expansion at another region of the AR NH2-terminal domain [14].

The AR has multiple phosphorylation sites that occur predominantly in the NH2-terminal region
and include Ser-Pro sequences [15].

Thus far, specific functions have not been attributed to AR phosphorylation or to phosphorylation of the steroid hormone receptors in general. While all of the steroid
receptors contain multiple phosphorylation sites, most studies have failed to define their functional significance.

DNA-binding domain

The central region of the AR is the DNA-binding domain. It consists of amino acid residues 559�??624 in human AR. The DNA-binding domain is comprised of two zinc-finger structures typical of steroid receptors [16] and mediates AR binding to DNA as a dimer [17].

The DNA-binding domain binds androgen
response element DNA to mediate androgen-induced gene transcription [18,19]. Some of the
androgen response elements associated with androgen-regulated genes are simple elements that conform to the consensus sequence 5�?�GGTACAnnnTGTTCT3�?�.

Others have more complex sequences. A
number of androgen-regulated genes have been identified that contain simple or complex androgen response elements [20�??23], including the androgen responsive regions of prostate specific antigen [24],
probasin [25,26], and the Slp gene [27].

The DNA-binding domain also functions in interactions with coactivators such as protein inhibitor of activated STAT-1, which increases AR-mediated gene activation [28,29]. Another DNA-binding domain interacting protein is a small nuclear RING finger protein which increased AR transactivation [30].

The DNA-binding domain is contiguous with a hinge region that spans amino acid residues
625�??675. The function of the hinge region is not well understood. Spanning the DNA binding and hinge regions is a bipartite nuclear targeting signal composed of two clusters of basic amino acids [31].

In transiently transfected COS cells, androgen binding activates the nuclear targeting signal to direct subcellular localization of the AR from the cytoplasm to the nucleus [7,31]. The subcellular localization of the endogenous AR has been difficult to establish, however.

In studies using tissue sections, endogenously expressed AR is nuclear in the presence of androgen, but is not easily detected in the absence of androgen [32], most likely due to its rapid degradation [6]. In normal skin fibroblasts and some cancerderived
cell lines, the AR is nuclear in the absence of dihydrotestosterone (DHT) [33].

Ligand-binding domain

The carboxyl-terminal region from amino acid residues 676�??919 makes up the ligand-binding domain. Structural aspects of the ligand-binding domain of many steroid receptors have been elucidated through crystallization studies as recently reported for the AR [34,35].

Crystal structure analysis has revealed
multiple alpha helices folded to create a hydrophobic pocket for hormone binding. Binding of the steroid completes the hydrophobic center of the ligand-binding domain and repositions helix 12 [36].

In the presence of agonist binding, a hydrophobic binding surface forms in the ligand-binding domain known as activation function 2 (AF2). AF2 binds the p160 family of activators which have histone acetyltransferase activity.

Binding occurs through the LXXLL motifs of the p160 coactivators, where L
is leucine and X is any amino acid. The AF2 binding surface for some receptors also serves as the binding site for the LXXLL-like sequences present in corepressors.

The nature of the ligand bound in the
ligand-binding pocket, whether agonist or antagonist, determines the conformation of AF2 to favor either
coactivator or corepressor binding.

Steroid-binding specificity and kinetics

The AR binds the biologically active androgens, testosterone, and DHT, with the same apparent equilibrium binding affinity of Kd 0.1�??0.3 nM. Yet, DHT is a more effective androgen than testosterone in part because it dissociates more slowly from the AR.

The dissociation half-time of DHT is about 3 times slower than that of testosterone [37]. The similar binding affinity and different dissociation rates was supported by differences in androgen association rates [37].

Other steroids such as estradiol and progesterone bind the AR with lower affinity, causing AR nuclear transport, but are less effective in activating reporter vectors in transient transfection studies, requiring high concentrations [6].

Recent studies indicate that the slow dissociation rate of bound androgen results in part from an NH2-terminal and carboxyl-terminal (N/C) interaction discussed below.

Androgen antagonists bind the AR and inhibit androgen-induced gene activation. The most notable AR antagonist is hydroxyflutamide, which is the active metabolite of flutamide, a pharmaceutical drug administered for the treatment of prostate cancer.

Hydroxyflutamide binds AR with an apparent
binding affinity of 175 nM [38], which is 3 orders of magnitude weaker than the binding affinity of testosterone and DHT. Other pharmaceutical antagonists in use in prostate cancer therapy include casodex (bicalutamide) and nilutamide.

The mechanism of inhibition of these antagonists is competition for androgen binding and inhibition of AR DNA binding, as shown for hydroxyflutamide [39]. One antagonist,
RU56187, binds the AR with an affinity (Kd 0.39 nM) similar to that for testosterone and DHT
[38]. However, the dissociation half-time of [3H]RU56187 is 5 min at 35 °C compared to 2.5 h for
[3H]R1881 [38]. Thus, one distinguishing feature of AR agonists and antagonists is a more rapid dissociation
rate of antagonists. This occurs in part because antagonists fail to induce the N/C interaction
[40]. Depending on the binding affinity, antagonists require sufficiently high concentrations to compete
for binding of the active androgens to block agonist-induced gene transcription. Environmental antiandrogens bind the AR with relatively low affinity and would be expected to have rapid binding and dissociation kinetics. Environmental antiandrogens, therefore, require relatively high concentrations in accordance with their lower binding affinity to elicit an antagonistic effect.

Androgen receptor stabilization and the N/C interaction

Several years ago, we discovered an NH2-terminal and carboxyl-terminal (N/C) interaction in the AR
[17,40]. The N/C interaction is remarkably specific in that it is induced by ligands that display androgen
agonist activity in vivo, such as testosterone and DHT [41]. Furthermore, the agonist-induced N/C
interaction is inhibited by antagonist binding [40]. Thus, the ligand requirements for the N/C interaction reflect the biological activity of AR as observed in vivo suggesting it is important to AR function.

Based on studies using mutant receptors that cause the androgen insensitivity syndrome, we proposed a model for an antiparallel dimer of the AR where the N/C interaction directly participates in AR dimerization
in association with DNA binding [40,42]. Studies by other laboratories have confirmed the N/C
interaction in the AR [43�??49] and for other nuclear receptors [50�??53].

Recent studies have localized the regions in the AR ligand-binding domain and NH2-terminal region required for the N/C interaction.

Through the use of selective AR mutants that cause the androgen insensitivity syndrome, we showed that the binding site in the ligand-binding domain for the NH2-terminal region overlaps with the binding site for the p160 coactivators [54].

The coactivator binding site in the ligand-binding domain is known as activation function 2 (AF2). Interaction of the p160 coactivators
with AF2 is mediated by multiple LXXLL motifs.

We searched for similar motif sequences in the
AR NH2-terminal region. Two motifs were identified, FXXLF and WXXLF, with the sequences
23FQNLF27 and 433WHTLF437, where F is phenylalanine and W is tryptophan.

Each binding motif is predicted to form an amphipathic alpha helix and interact with AF2 in the presence of androgen to mediate
the N/C interaction [55]. An interesting aspect of these studies is that the FXXLF motif is present in several previously reported AR coactivators [56].

The studies indicated that the FXXLF interacting
motif is specific for the AR.

Because of the overlapping binding sites present in AF2 for the LXXLL motif of p160 coactivators and the FXXLF motif in the AR, we determined whether competitive inhibition occurs.

We showed that the N/C interaction inhibits the recruitment of p160 coactivators [57]. Thus, one function of the agonist- induced N/C interaction may be to limit AR activation through AF2.

On the other hand, there may be a temporal sequence of interactions between AF2 and the FXXLF and LXXLL motifs that does not
preclude AR activation by p160 coactivators through the AF2 domain.

Other coactivators and interacting proteins that contain the FXXLF motif may interact with the AF2 binding surface at different times during the process of AR-mediated gene activation.

Recent studies showed that the androgen-dependent N/C interaction mediated by the FXXLF and WXXLF motifs is required for the activation of several naturally occurring androgen-regulated genes including PSA and probasin [58].

This was in striking contrast to the mouse mammary tumor virus long terminal repeat and Slp androgen-responsive regions, which showed less dependence on the N/C interaction
for activation. It is not known what distinguishing properties of these androgen-responsive regions require an AR N/C interaction for transactivation.

With few exceptions, compounds with AR agonist activity in vivo induce the N/C interaction.
This includes the lower-affinity anabolic steroids such as oxandrolone and fluoxymesterone, which bind AR with an equilibrium binding affinity of 62 and 44 nM, respectively [38].

These are potent androgens in vivo, supporting an in vivo role for the N/C interaction in AR activity. This contrasts other steroids such as estradiol and progesterone, which bind AR with a similar moderate affinity, but which
are ineffective in activating the AR in vivo.

Specificity of the N/C interaction for agonists and antagonists makes it a useful assay to screen compounds for endocrine disruptor activity. The two hybrid mammalian
cell assay used for the N/C interaction was recently described in detail [59].

It utilizes the GAL4 DNA-binding domain fusion protein with the AR ligand-binding domain and the VP16 transactivation domain fusion protein with the AR NH2-terminal and DNA-binding domains. The reporter vector contains
multiple binding sites for the GAL4 DNA-binding domain and the luciferase gene for detection.

Nuclear coactivators of the androgen receptor

Many proteins have been reported to interact with the AR and function as AR coactivators.

Some of these include Ets [60], c-Jun [61,62], TFIIF [63], TFIIH [64], retinoblastoma protein [65], CREB-binding protein [66], BAG-1L [67], ARA70/ELE1α [68�??70], ARIP3 [71], p160s [72,73], ARA160 [74], ARA54 [75], ARA55/Hic5 [76,77], β-catenin [78,79], FHL2 [80], HBO1 [81], cyclin E [82], cyclin D1
[83], PDEF [84], BRCA1 [85], P-TEFb [86], caveolin-1 [87], and ARA24 [88].

Many of the reports utilized
yeast two hybrid screening methods to detect interacting proteins and made use of transient transfection studies to demonstrate increased transcriptional activity mediated by the AR.

There are as yet few or no studies that directly link an AR interacting protein with AR functional activity in vivo. Knock-out studies of the p160 coactivators in mice have failed to significantly impact male reproductive
development and function [89�??91].

This type of study is complicated, however, by the compensating effects of other coactivators that may become expressed at increased levels. Another complication in determining the functional significance of an AR interacting protein results from limitations of conditions
used for transient transfection assays.

We [56] and others [92] have observed that the use of balancing DNA additions in transient cotransfection assays inhibit AR ranscriptional activity in controls,
but not necessarily in samples expressing the coactivator being tested.

The mechanism of inhibition has
not been defined, but may include inhibition of AR expression [92] or inhibition of AR functional activity.

The result is an apparent increase in AR-mediated transactivation by the putative coactivator under study, which may not be observed without the inhibitory effect. Conclusions regarding many of the interacting proteins that show apparent increases in AR transcriptional activity, therefore, require
further study to clearly establish their role in AR function.

[u]ANDROGEN RECEPTOR GENE MUTATIONS

Androgen insensitivity syndrome[/u]

Male sexual development depends on androgen-induced gene transcription. This occurs in the human embryo between 8 and 12 weeks of gestation. At this critical period, the external genitalia of the male forms, and interference with androgen action at this time results in different degrees of incomplete masculinization.

At birth, the androgen-insensitive genetic male external genital phenotype can vary from
near complete masculinization to ambiguous genitalia, or an apparent normal female.

The requirement for the AR in this process has been well documented in the androgen insensitivity syndrome. In this syndrome, 46XY genetic males have a mutation in the AR gene, which results in different degrees of loss of AR function depending on the specific mutation [93].

There have been approximately 230 different
mutations identified in the AR gene that cause androgen insensitivity. These are summarized at
<www.mcgill.ca/androgendb/>.

AR mutations that cause androgen insensitivity include partial or complete AR gene deletions
[94,95] and nonsense or missense mutations [96�??99]. Frameshift mutations that result in the premature stop codon sequence destabilize the messenger RNA and can result in a truncated AR protein [100].

In cases of partial androgen insensitivity, the function of the AR is not entirely disrupted, resulting in different degrees of incomplete virilization in the newborn [101].

Thus, the full function of the AR is required
for male sexual development to occur. Exposure to sufficient levels of environmental antiandrogens could have a similar effect of inhibiting AR-mediated gene transcription with partial or complete interference of male sexual development in utero.

The androgen insensitivity syndrome, therefore, unequivocally demonstrates the requirement for the AR in male sexual development. Similar phenotypic disruptions could result by interrupting AR-mediated gene activation by the presence of environmental androgen antagonists.

Androgen receptor in prostate cancer

Androgens are required for prostate growth and likely have role in excessive tissue growth associated with benign prostate hyperplasia and prostate cancer [33].

Accordingly, antiandrogens are frequently
used in the treatment of prostate cancer. Antiandrogens at moderate concentrations block androgen-induced stimulation of the prostate [102].

However, the lower-affinity environmental antiandrogens or androgens likely have little impact on benign prostatic hyperplasia or prostate cancer.

Some reports have suggested that inappropriate exposure in utero to environmental estrogenic toxicants can increase prostate growth and development later in life [103], although the significance of lose-dose effects to environmental contaminants has recently been challenged [104].

Adult males are exposed to relatively
high circulating androgen levels that would not be influenced by environmental antiandrogens or androgens.

It should nevertheless be considered that some stages of prostate cancer are sensitive to low
concentrations of androgen through mechanisms not yet understood [33,105]. In patients treated with androgen withdrawal therapy, exposure to androgens could be detrimental.

High p160 coactivator expression has been reported in recurrent prostate cancer in the androgen-withdrawn patient, which may
contribute to an increased sensitivity to androgen [105].

It is unlikely that environmental androgens or
antiandrogens would be in sufficiently high concentrations to impact these examples of increased prostate growth.

[u]RISK ASSESSMENT OF ANTIANDROGENS AND ANDROGENS AS ENVIRONMENTAL
ENDOCRINE DISRUPTORS

Environmental antiandrogens[/u]

A number of chemicals used in agricultural weed and pest control have been identified as precursors to environmental antiandrogens. The pesticides p,p�?�-DDT [1,1,1-trichloro-2,2-bix(p-chlorophenyl)ethane] [106] and methoxychlor [2,2-bis (p-methoxyphenol)-1,1,1-trichloroethane] [107] are metabolized to
more potent compounds with androgen antagonist activity.

The AR antagonist activity of p,p�?�-DDT derives
from its metabolite p,p�?�-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], which binds the AR with an apparent equilibrium binding affinity of Kd 3.5 μM [106].

The potency of p,p�?�-DDE as an endocrine
disruptor is increased because of its long biological half-life, which was estimated to be only slightly less than the average human life span.

The long half-life of p,p�?�-DDE derives from its solubility in fat stores from where it is released during mobilization of fat and lactation. The active metabolite of methoxychlor is HPTE [2,2-bis (p-hydroxyphenol)-1,1,1-trichloroethane], which binds AR with an equilibrium binding affinity of Kd 1.4 μM [107].

HPTE has a high turnover rate in the body and thus a lower potential as an endocrine disruptor in human development and health. While p,p�?�-DDT is no longer in use in the United States as a pesticide, methoxychlor is an actively used pesticide and thus could be a source of antiandrogen activity in the environment.

The fungicide vinclozolin is currently in use in the United States. Vinclozolin [3-(3,5-dichlorophenyl)-5-methyl-5-vinyloxazolidine-2,4-dione] is metabolized to M2 (3�?�,5�?�-dichloro-2-hydroxy-2-methylbut-3-enanilide), an androgen antagonist that binds the AR with an affinity of Kd 9.7 μM [39,108].

Administration of vinclozolin to pregnant rats inhibits male reproductive tract development in male offspring, indicating its androgen antagonist activity [109,110].

Other potential environmental antiandrogen precursors include procymidone [N-(3,5-dichlorophenyl)- 1,2-dimethylcyclopropane-1,2-dicarboximide], a fungicide with antiandrogen activity in experimental animals [111]. The active metabolite of procymidone remains uncharacterized.

Other environmental contaminants disrupt male reproductive development through mechanisms that are thought to be independent of the AR. These include di(n-butyl) phthalate, a widely used commercial plasticizer present in fatty foods [112].

Dibutylphthalate is metabolized to the active mono (n-butyl) phthalate and inhibits testosterone biosynthesis [112,113]. The reported increased incidence of male reproductive tract abnormalities in the human population in some parts of the world has raised concerns about the role for environmental contaminants with antiandrogen activity.

The question of declining sperm counts worldwide or regionally was recently addressed.

Most evidence supports regional declines, but controversy remains over the reliability of historical data [114]. The role of environmental antiandrogens in inhibiting spermatogenesis has not been addressed, but could reflect global effects of environmental contaminants.

Another male developmental
abnormality of incomplete masculinization with reported increased frequency is hypospadias deformity, where the urethra opens on the shaft or base of the penis rather than at the tip [115].

Hypospadias is a relatively common developmental abnormality of the human male fetus, occurring at a rate as high
as 40 in 10 000 newborn male infants [115,116]. In the United States, the incidence of hypospadias reached a high level in the 1980s, but has since declined [117].

It is not clear what role endocrine disruptors
have in the etiology of hypospadias in the newborn.

Environmental androgens

Effluent from paper mills flowing into a Florida river was postulated to contain substances with androgen activity based on the masculinization of entire populations of Gambusia affinis holbrooki female
mosquitofish [118].

One active substance was identified as androstenedione present in the river at concentrations of 0.14 nM [119]. Previous studies showed that short exposure to higher concentrations of androstenedione masculinized the anal fin or gonopodium used in male reproduction [118].

Thus, aquatic wildlife in areas of paper mill discharge are at increased risk of reproductive tract abnormalities due to the presence of androgen precursors in the river water [120].

It was postulated that the abundant phytosterols from pine tree oils, including β-sitosterol, campesterol and stigmastanol, act as substrates for bacteria like the common bacterium Mycobacterium sp. [119], which was shown to metabolize phytosterols to androstenedione [121,122].

Other studies confirmed the presence of androgen activity in river water downstream of a paper mill, but as yet no additional specific compounds have been identified [123]. Ongoing studies of river water extracts indicate the presence of additional compounds with
androgen activity.

Preliminary evidence indicates that their structure differs from the known steroids.
There is also recent evidence that other substances with androgen activity are present in the control river [124].

Another potential source for environmental androgens is excreted anabolic steroids administered to cattle to improve beef production [125]. The anabolic steroid trenbolone acetate is rapidly converted
in vivo to 17β-trenbolone, an active metabolite with androgen activity.

In a number of in vitro assays, trenbolone has a potency similar to the most active androgens known such as DHT and the synthetic
androgen R1881 (methyltrienolone) [125].

Detection of reproductive abnormalities in fish exposed to effluent from feed lots has raised questions whether the masculinizing effects result from excretion products that contaminate the water.

This type of environmental contamination by pharmaceutical byproducts in water sources may be widespread resulting from human or livestock drug use. Such contamination allows for possible exposure to high-affinity compounds, which if not eliminated by water purification procedures, can expose wildlife and human populations.

An environmental threat, therefore, exists, especially to aquatic wildlife that live in contaminated waters that contain effluent from paper mills or feedlots, as evidenced by the increased incidence of reproductive abnormalities.

It is yet unclear to what extent these androgen precursors, anabolic steroids, or metabolites impact the human population. The presence of high-affinity compounds or androgen precursors lowers the exposure requirements for a detrimental effect.

Further study of these contaminants
with high affinity for the AR will reveal the overall threat to wildlife and human populations.

Risk assessment

Several criteria must be considered in the risk assessment of environmental antiandrogens and androgens.

These include (a) exposure levels, (b) in vivo metabolic activation, © biological half-life of the active metabolites, (d) binding affinity and activity for the AR, and (e) the developmental stage of exposure.

(a) The level of exposure of the human population to environmental androgens or antiandrogens in most cases is not known. The relatively low binding affinities of the environmental antiandrogens discovered thus far would require significant exposure levels for an antagonistic effect to occur.

Exposure to endocrine disruptors with antiandrogen activity may be an occupational hazard and thus limited to select populations involved in chemical production or farming practices.

In contrast, the presence of high-affinity compounds derived from pharmaceutical and personal care products reduces the exposure requirements for a detrimental impact.

(b) Metabolic activation was observed with all of the environmental antiandrogens derived from pesticides and herbicides. This indicates the importance of screening with assay techniques that allow for metabolic processes to occur.

In vitro binding assays using inactive parent compounds and isolated receptor preparations could preclude the identification of androgen antagonists or agonists since metabolic conversion may not occur.

Metabolic activation necessitates the use of
biological systems such as mammalian cell lines that utilize the correct metabolic enzyme pathways.

For example, in yeast-based assays, metabolic conversion may not occur or may occur
through alternative pathways not applicable to mammalian cells. Ideally, in vivo whole animal experiments may be required to demonstrate the activity of a compound.

However, such an initial screening approach would be expensive and laborious. In the case of vinclozolin, mammalian cell-based assays displayed the same metabolic conversions that occur in the whole animal [39].

For a clear documentation of the inhibitory effects, the active metabolites must be identified and
confirmed.

© Long half-lives of active endocrine disruptors can result from high fat solubility, a property applicable to most steroidal compounds that interact with the ligand-binding domain of steroid receptors.

When fat stores are mobilized, the potential impact to human health increases. In addition,
steroids or steroid-like compounds can accumulate in wildlife species to be passed up the food chain or to increase the body load to levels sufficient for inhibitory or stimulatory effects to
occur.

(d) The environmental antiandrogens discovered thus far have relatively low binding affinities for the AR. This necessitates relatively high exposure levels for an inhibitory effect, which may only occur during occupational exposure.

On the other hand, the presence of pharmaceutical and personal
care products such as cholesterol-lowering drugs and steroids like estrone in water sources, raises new threats of the presence of high-affinity steroids and ligands that would require lower exposure levels for a detrimental effect.

It was shown that some pharmaceutical products detected in the environment are associated with populations of feminized male fish, thus broadening the involvement of environmental contaminants in male reproductive abnormalities [126].

The detection of pharmaceutical and personal care products in the environment, which characteristically have high binding affinities for the AR, reduces the exposure levels required for a detrimental effect.

(e) Risk assessment should consider the developmental period of exposure. The developing male fetus is sensitive to the presence of antiandrogens since the male embryo depends on androgeninduced gene transcription during the critical period of male sexual development [127].

Periods of increased fetal sensitivity to exposure to antiandrogen activity from the fungicide vinclozolin were identified in a study of rats.

The most sensitive period to the antiandrogenic effects of vinclozolin was rat gestational day 16 and 17, with the sensitive period ranging from gestational day 14 to 19, the time of male sexual development [128].

The relatively weak binding affinities of the
known environmental antiandrogens for the AR necessitates relatively high exposure levels for a biological impact. It remains to be established whether any of the environmental antiandrogens identified thus far reach levels that are sufficient to interfere with normal human reproductive development.

It was recently suggested that the lack of feedback regulation at the hypothalamus and pituitary by fetal androgens during development may increase the inhibitory effects of an antiandrogen [129]. In this case, androgen production by the fetal testis is induced by placental human chorionic gonadotropin.

This could prevent a compensatory increase in androgen production in the presence of an antiandrogen, which could result in a more pronounced inhibitory effect.

REFERENCES

  1. D. B. Lubahn, D. R. Joseph, P. M. Sullivan, H. F. Willard, F. S. French, E. M. Wilson. Science
    240, 327�??330 (1988).
  2. C. J. Brown, S. J. Goss, D. B. Lubahn, D. R. Joseph, E. M. Wilson, F. S. French, H. F. Willard.
    Am. J. Hum. Genet. 44, 264�??269 (1989).
  3. D. B. Lubahn, D. R. Joseph, M. Sar, J. A. Tan, H. N. Higgs, R. E. Larson, F. S. French, E. M.
    Wilson. Mol. Endocrinol. 2, 1265�??1275 (1988).
  4. C. W. Gregory, B. He, E. M. Wilson. J. Mol. Endocrinol. 27, 309�??319 (2001).
  5. E. M. Wilson and F. S. French. J. Biol. Chem. 254, 6310�??6319 (1979).
  6. J. A. Kemppainen, M. V. Lane, M. Sar, E. M. Wilson. J. Biol. Chem. 267, 968�??974 (1992).
  7. J. A. Simental, M. Sar, M. V. Lane, F. S. French, E. M. Wilson. J. Biol. Chem. 266, 510�??518
    (1991).
  8. Z. X. Zhou, C. I. Wong, M. Sar, E. M. Wilson. Rec. Prog. Hormone Res. 49, 249�??274 (1994).
  9. C. S. Choong and E. M. Wilson. J. Mol. Endocrinol. 21, 235�??257 (1998).
  10. P. M. Bingham, M. O. Scott, S. Wang, M. J. McPhaul, E. M. Wilson, J. Y. Garbern, D. E. Merry,
    K. H. Fischbeck. Nat. Genet. 9, 191�??196 (1995).
  11. A. R. La Spada, E. M. Wilson, D. B. Lubahn, A. E. Harding, K. H. Fischbeck. Nature 352, 77�??79
    (1991).
  12. C. S. Choong, J. A. Kemppainen, Z. X. Zhou, E. M. Wilson. Mol. Endocrinol. 10, 1527�??1535
    (1996).
  13. C. S. Choong, J. A. Kemppainen, E. M. Wilson. J. Mol. Evol. 47, 334�??342 (1998).
  14. J. A. Tan, D. R. Joseph, V. E. Quarmby, D. B. Lubahn, M. Sar, F. S. French, E. M. Wilson. Mol.
    Endocrinol. 2, 1276�??-1285 (1988).
  15. Z. X. Zhou, J. A. Kemppainen, E. M. Wilson. Mol. Endocrinol. 9, 605�??615 (1995).
  16. L. P. Freedman. Endocrine Rev. 13, 129�??145 (1992).
  17. C. I. Wong, Z. X. Zhou, M. Sar, E. M. Wilson. J. Biol. Chem. 268, 19004�??19012 (1993).
  18. K. C. Ho, K. B. Marschke, J. A. Tan, S. G. A. Power, E. M. Wilson, F. S. French. J. Biol. Chem.
    268, 27226�??27235 (1993).
  19. J. A. Tan, K. B. Marschke, K. C. Ho, S. T. Perry, E. M. Wilson, F. S. French. J. Biol. Chem. 267,
    4456�??4466 (1992).
  20. K. C. Ho, V. E. Quarmby, F. S. French, E. M. Wilson. J. Biol. Chem. 267, 12660�??12667 (1992).
  21. K. C. Ho, R. Snoek, V. E. Quarmby, D. H. Viskochil, P. S. Rennie, E. M. Wilson, F. S. French, N.
    Bruchovsky. Biochemistry 28, 6367�??6373 (1989).
  22. N. J. Charest, D. R. Joseph, E. M. Wilson, F. S. French. Mol. Endocrinol. 2, 999�??1004 (1988).
  23. D. H. Viskochil, S. T. Perry, O. A. Lea, D. W. Stafford, E. M. Wilson, F. S. French. J. Biol. Chem.
    258, 8861�??8866 (1983).
  24. K. B. J. M. Cleutjens, H. A. G. M van der Korput, C. C. Ehren-van Eekelen, R. A. Sikes, C.
    Fasciana, L. W. Chung, J. Trapman. Mol. Endocrinol. 11, 1256�??1265 (1997).
  25. N. M. Greenberg, F. J. DeMayo, P. C. Sheppard, R. Barrios, R. Lebovitz, M. Finegold, R.
    Angelopoulou, J. G. Dodd, M. L. Duckworth, J. M. Rosen, R. J. Matusik. Mol. Endocrinol. 8,
    230�??239 (1994).
  26. S. Kasper, P. S. Rennie, N. Bruchovsky, P. C. Sheppard, H. Cheng, L. Lin, R. P. C. Shiu, R. Snoek,
    R. J. Matusik. J. Biol. Chem. 269, 31763�??31769 (1994).
  27. A. Scheller, R. I. Scheinman, E. Thompson, C. O. Scarlett, D. M. Robins. Mol. Cell. Endocrinol.
    121, 75�??86 (1996).
  28. J. A. Tan, S. H. Hall, K. G. Hamil, G. Grossman, P. Petrusz, J. Liao, K. Shuai, F. S. French. Mol.
    Endocrinol. 14, 14�??26 (2000).
  29. J. A. Tan, S. H. Hall, K. G. Hamil, G. Grossman, P. Petrusz, F. S. French. J. Biol. Chem. 277,
    16993�??17001 (2002).
  30. A. M. Moilanen, H. Poukka, U. Karvonen, M. Häkli, O. A. Jänne, J. J. Palvimo. Mol. Cell. Biol.
    18, 5128�??5139 (1998).
  31. Z. X. Zhou, M. Sar, J. A. Simental, M. V. Lane, E. M. Wilson. J. Biol. Chem. 269, 13115�??13123
    (1994).
  32. M. Sar, D. B. Lubahn, F. S. French, E. M. Wilson. Endocrinology 127, 3180�??3186 (1990).
  33. C. W. Gregory, R. T. Johnson, J. L. Mohler, F. S. French, E. M. Wilson. Cancer Res. 61,
    2892�??2898 (2001).
  34. P. M. Matias, P. Donner, R. Coelho, M. Thomaz, C. Peixoto, S. Macedo, N. Otto, S. Joschko, P.
    Scholz, A. Wegg, S. Bäsler, M. Schäfer, U. Egner, M. A. Carrondo. J. Biol. Chem. 275,
    26164�??26171 (2000).
  35. J. S. Sack, K. F. Kish, C. Wang, R. M. Attar, S. E. Kiefer, Y. An, G. Y. Wu, J. E. Scheffler, M. E.
    Salvati, S. R. Krystek, R. Weinmann, H. M. Einspahr. Proc. Natl. Acad. Sci. USA 98, 4904�??4909
    (2001).
  36. J. P. Renaud, N. Rochel, M. Ruff, V. Vivat, P. Chambon, H. Gronemeyer, D. Moras. Nature 378,
    681�??689 (1995).
  37. E. M. Wilson and F. S. French. J. Biol. Chem. 251, 5620�??5629 (1976).
  38. J. A. Kemppainen, E. Langley, C. I. Wong, K. Bobseine, W. R. Kelce, E. M. Wilson. Mol.
    Endocrinol. 13, 440�??454 (1999).
  39. C. I. Wong, W. R. Kelce, M. Sar, E. M. Wilson. J. Biol. Chem. 270, 19998�??20003 (1995).
  40. E. Langley, Z. X. Zhou, E. M. Wilson. J. Biol. Chem. 270, 29983�??29990 (1995).
  41. Z. X. Zhou, M. V. Lane, J. A. Kemppainen, F. S. French, E. M. Wilson. Mol. Endocrinol. 9,
    208�??218 (1995).
  42. E. Langley, J. A. Kemppainen, E. M. Wilson. J. Biol. Chem. 273, 92�??101 (1998).
  43. P. Doesburg, C. W. Kuil, C. A. Berrevoets, K. Steketee, P. W. Faber, E. Mulder, A. O. Brinkmann,
    J. Trapman. Biochemistry 36, 1052�??1064 (1997).
  44. T. Ikonen, J. J. Palvimo, O. A. Jänne. J. Biol. Chem. 272, 29821-29828 (1997).
  45. C. A. Berrevoets, P. Doesburg, K. Steketee, J. Trapman, A. O. Brinkmann. Mol. Endocrinol. 12,
    1172�??1183 (1998).
  46. C. L. Bevan, S. Hoare, F. Claessens, D. M. Heery, M. G. Parker. Mol. Cell. Biol. 19, 8383�??8392
    (1999).
  47. T. Slagsvold, I. Kraus, T. Bentzen, J. Palvimo, F. Saatcioglu. Mol. Endocrinol. 14, 1603�??1617
    (2000).
  48. J. Thompson, F. Saatcioglu, O. A. Jänne, J. J. Palvimo. Mol. Endocrinol. 15, 923�??935 (2001).
  49. A. Bubulya, S. Y. Chen, C. J. Fisher, Z. Zheng, X. Q. Shen, L. Shemshedini. J. Biol. Chem. 48,
    44704�??44711 (2001).
  50. W. L. Kraus, E. M. McInerney, B. S. Katzenellenbogen. Proc. Natl. Acad. Sci. USA 92,
    12314�??12318 (1995).
  51. D. Shao, S. M. Rangwala, S. T. Bailey, S. L. Krakow, M. J. Reginato, M. A. Lazar. Nature 396,
    377�??380 (1998).
  52. M. J. Tetel, P. H. Giangrande, S. A. Leonhardt, D. P. McDonnell, D. P. Edwards. Mol. Endocrinol.
    13, 910�??924 (1999).
  53. R. Métivier, G. Penot, G. Flouriot, F. Pakdel. Mol. Endocrinol. 15, 1953�??1970 (2001).
  54. B. He, J. A. Kemppainen, J. J. Voegel, H. Gronemeyer, E. M. Wilson. J. Biol. Chem. 274,
    37219�??37225 (1999).
  55. B. He, J. A. Kemppainen, E. M. Wilson. J. Biol. Chem. 275, 22986�??22994 (2000).
  56. B. He, J. T. Minges, L. W. Lee, E. M. Wilson. J. Biol. Chem. 277, 10226�??10235 (2002).
  57. B. He, N. T. Bowen, J. T. Minges, E. M. Wilson. J. Biol. Chem. 276, 42293�??42301 (2001).
  58. B. He, L. W. Lee, J. T. Minges, E. M. Wilson. J. Biol. Chem. 277, 25631�??25639 (2002).
  59. E. M. Wilson, B. He, E. Langley. Meth. Enzym. 364 (2003).
  60. J. Schneikert, H. Peterziel, P. A. Defossez, H. Klocker, Y. de Launoit, A. C. B. Cato. J. Biol.
    Chem. 271, 23907�??23913 (1996).
  61. A. Bubulya, S. C. Wise, X. Q. Shen, L. A. Burmeister, L. Shemshedini. J. Biol. Chem. 271,
    24583�??24589 (1996).
  62. S. C. Wise, L. A. Burmeister, X. F. Zhou, A. Bubulya, J. L. Oberfield, M. J. Birrer. L.
    Shemshedini. Oncogene 16, 2001�??2009 (1998).
  63. I. J. McEwan, J. A. Gustafsson. Proc. Natl. Acad. Sci. USA 94, 8485�??8490 (1997).
  64. D. K. Lee, H. O. Duan, C. Chang. J. Biol. Chem. 275, 9308�??9313 (2000).
  65. J. Lu and M. Danielsen. J. Biol. Chem. 273, 31528�??31533 (1998).
  66. K. Fronsdal, N. Engedal, T. Slagsvold, F. Saatcioglu. J. Biol. Chem. 273, 31853�??31859 (1998).
  67. B. A. Froesch, S. Takayama, J. C. Reed. J. Biol. Chem. 273, 11660�??11666 (1998).
  68. S. Yeh and C. Chang. Proc. Natl. Acad. Sci. USA 93, 5517�??5621 (1996).
  69. P. Alen, F. Claessens, E. Schoenmakers, J. V. Swinnen, G. Verhoeven, W. Rombauts, B. Peeters.
    Mol. Endocrinol. 13, 117�??128 (1999).
  70. Z. X. Zhou, B. He, S. H. Hall, E. M. Wilson, F. S. French. Mol. Endocrinol. 16, 287�??300 (2002).
  71. A. M. Moilanen, U. Karvonen, H. Poukka, W. Yan, J. Toppari, O. A. Jänne, J. J. Palvimo. J. Biol.
    Chem. 274, 3700�??3704 (1999).
  72. H. Ma, H. Hong, S. M. Huang, R. A. Irvine, P. Webb, P. J. Kushner, G. A. Coetzee, M. R.
    Stallcup. Mol. Cell. Biol. 19, 6164�??6173 (1999).
  73. T. Slagsvold, I. Kraus, K. Fronsdal, F. Saatcioglu. J. Biol. Chem. 276, 31030�??31036 (2001).
  74. P. W. Hsiao and C. Chang. J. Biol. Chem. 274, 22373�??22379 (1999).
  75. H. Y. Kang, S. Yeh, N. Fujimoto, C. Chang. J. Biol. Chem. 274, 8570�??8576 (1999).
  76. N. Fujimoto, S. Yeh, H. Y. Kang, S. Inui, H. C. Chang, A. Mizokami, C. Chang. J. Biol. Chem.
    274, 8316�??8321 (1999).
  77. L. Yang, J. Guerrero, H. Hong, D. B. DeFranco, M. R. Stallcup. Mol. Biol. Cell 11, 2007�??2018
    (2000).
  78. C. I. Truica, S. Byers, E. P. Gelmann. Cancer Res. 60, 4709�??4713 (2000).
  79. J. E. Pawlowski, J. R. Ertel, M. P. Allen, M. Xu, C. Butler, E. M. Wilson, M. E. Wierman. J. Biol.
    Chem. 277, 20702�??20710 (2002).
  80. J. M. Müller, U. Isele, E. Metzger, A. Rempel, M. Moser, A. Pscherer, T. Breyer, C. Holubarsch,
    R. Buettner, R. Schüle. EMBO J. 19, 359�??369 (2000).
  81. M. Sharma, M. Zarnegar, X. Li, B. Lim, Z. Sun. J. Biol. Chem. 275, 35200�??35208 (2000).
  82. A. Yamamoto, Y. Hashimoto, K. Kohri, E. Ogata, S. A. Kato, K. Ikeda, M. Nakanishi. J. Cell Biol.
    150, 873�??879 (2000).
  83. A. T. Reutens, M. Fu, C. Wang, C. Albanese, M. J. McPhaul, Z. Sun, S. P. Balk, O. A. Janne, J. J.
    Palvimo, R. G. Pestell. Mol. Endocrinol. 15, 797�??811 (2001).
  84. P. Oettgen, E. Finger, Z. Sun, Y. Akbarali, U. Thamrongsak, J. Boltax, F. Grall, A. Dube, A.
    Weiss, L. Brown, G. Quinn, K. Kas, G. Endress, C. Kunsch, T. A. Libermann. J. Biol. Chem. 275,
    1216�??1225 (2000).
  85. S. Yeh, Y. C. Hu, M. Rahman, H. K. Lin, C. L. Hsu, H. J. Ting, H. Y. Kang, C. Chang. Proc. Natl.
    Acad. Sci. USA 97, 11256�??11261 (2000).
  86. D. K. Lee, H. O. Duan, C. Chang. J. Biol. Chem. 276, 9978�??9984 (2001).
  87. M. L. Lu, M. C. Schneider, Y. Zheng, X. Zhang, J. P. Richie. J. Biol. Chem. 276, 13442�??13451
    (2001).
  88. P. W. Hsiao, D. L. Lin, R. Nakao, C. Chang. J. Biol. Chem. 274, 20229�??20234 (1999).
  89. J. Xu, Y. Qiu, F. J. DeMayo, S. Y. Tsai, M. J. Tsai, B. W. O�??Malley. Science 279, 1922�??1925
    (1998).
  90. J. Xu, L. Liao, G. Ning, H. Yoshida-Komiya, C. Deng, B. W. O�??Malley. Proc. Natl. Acad. Sci.
    USA 97, 6379�??6384 (2000).
  91. Z. Wang, D. W. Rose, O. Hermanson, F. Liu, T. Herman, W. Wu, D. Szeto, A. Gleiberman, A.
    Krones, K. Pratt, R. Rosenfeld, C. K. Glass, M. G. Rosenfeld. Proc. Natl. Acad. Sci. USA 97,
    13549�??13554 (2000).
  92. K. Hofman, J. V. Swinnen, F. Claessens, G. Verhoeven, W. Heyns. Mol. Cell. Endocrinol. 168,
    21�??29 (2000).
  93. C. A. Quigley, A. De Bellis, K. B. Marschke, M. K. El-Awady, E. M. Wilson, F. S. French.
    Endocrine Rev. 16, 271�??321 (1995).
  94. C. A. Quigley, B. A. J. Evans, J. A. Simental, K. B. Marschke, M. Sar, D. B. Lubahn, P. Davies,
    I. A. Hughes, E. M. Wilson, F. S. French. Mol. Endocrinol. 6, 1103�??1112 (1992).
  95. C. A. Quigley, K. J. Friedman, A. Johnson, R. G. Lafreniere, L. M. Silverman, D. B. Lubahn,
    T. R. Brown, E. M. Wilson, H. F. Willard, F. S. French. J. Clin. Endocrinol. Metab. 74, 927�??933
    (1992).
  96. C. S. Choong, C. A. Quigley, F. S. French, E. M. Wilson. J. Clin. Invest. 98, 1423�??1431 (1996).
  97. A. De Bellis, C. A. Quigley, N. F. Cariello, M. K. El-Awady, M. Sar, M. V. Lane, E. M. Wilson,
    F. S. French. Mol. Endocrinol. 6, 1909�??1920 (1992).
  98. W. G. Yarbrough, V. E. Quarmby, J. A. Simental, D. R. Joseph, M. Sar, D. B. Lubahn, K. L.
    Olsen, F. S. French, E. M. Wilson. J. Biol. Chem. 265, 8893�??8900 (1990).
  99. D. B. Lubahn, T. R. Brown, J. A. Simental, H. N. Higgs, C. J. Migeon, E. M. Wilson, F. S. French.
    Proc. Natl. Acad. Sci. USA 86, 9534�??9538 (1989).
  100. N. J. Charest, Z. X. Zhou, D. B. Lubahn, K. L. Olsen, E. M. Wilson, F. S. French. Mol.
    Endocrinol. 5, 573�??581 (1991).
  101. A. De Bellis, C. A. Quigley, K. B. Marschke, M. K. El-Awady, M. V. Lane, E. P. Smith, M. Sar,
    E. M. Wilson, F. S. French. J. Clin. Endocrinol. Metab. 78, 513�??522 (1994).
  102. J. A. Kemppainen and E. M. Wilson. Urology 48, 157�??163 (1996).
  103. F. S. vom Saal, B. G. Timms, M. M. Montano, K. A. Thayer, S. C. Nagel, M. G. Dhar, V. K.
    Ganjam, S. Parmigiani, W. V. Welshons. Proc. Natl. Acad. Sci. USA 94, 2056�??2061 (1997).
  104. S. H. Safe. Environ. Health Perspect. 108, 487�??493 (2000).
  105. C. W. Gregory, B. He, R. T. Johnson, O. H. Ford, J. L. Mohler, F. S. French, E. M. Wilson. Cancer
    Res. 61, 4315�??4319 (2001).
  106. W. R. Kelce, C. R. Stone, S. C. Laws, L. E. Gray, J. A. Kemppainen, E. M. Wilson. Nature 375,
    581�??585 (1995).
  107. W. R. Kelce, C. R. Lambright, T. E. Wiese, L. E. Gray, C. I. Wong, E. M. Wilson. (2003). In
    preparation.
  108. W. R. Kelce and E. M. Wilson. J. Mol. Med. 75, 198�??207 (1997).
  109. L. E. Gray, J. S. Ostby, W. R. Kelce. Toxicol. Appl. Pharmacol. 129, 46�??52 (1994).
  110. W. R. Kelce, E. Monosson, M. P. Gamcsik, S. C. Laws, L. E. Gray. Toxicol. Appl. Pharmacol.
    126, 276�??285 (1994).
  111. S. Hosokawa, M. Murakami, M. Ineyama, T. Yamada, Y. Koyama, Y. Okuno, A. Yoshitake, H.
    Yamada, J. Miyamoto. J. Toxicol. Sci. 18, 111�??124 (1993).
  112. E. Mylchreest, D. G. Wallace, R. C. Cattley, P. M. D. Foster. Toxicol. Sci. 55, 143�??151 (2000).
  113. E. Mylchreest, M. Sar, R. C. Cattley, P. M. D. Foster. Toxicol. Appl. Pharmacol. 156, 81�??95
    (1999).
  114. S. H. Swan, E. P. Elkin, L. Fenster. Environ. Health Perspect. 108, 961�??966 (2000).
  115. M. Aho, A. M. Koivisto, T. L. J. Tammela, A. Auvinen. Environ. Health Perspect. 108, 463�??465
    (2000).
  116. L. J. Paulozzi, J. D. Erickson, R. J. Jackson. Pediatrics 100, 831�??834 (1997).
  117. L. J. Paulozzi. Environ. Health Perspect. 107, 297�??302 (1999).
  118. W. Howell, A. Black, S. Bortone. Copeia 4, 676�??681 (1980).
  119. R. Jenkins, R. A. Angus, H. McNatt, W. M. Howell, J. A. Kemppainen, M. Kirk, E. M. Wilson.
    Environ. Toxicol. Chem. 20, 1325�??1331 (2001).
  120. J. Raloff. Science News 159, 8�??10 (2001).
  121. W. J. Marsheck, S. Kraychy, R. D. Muir. Appl. Microbiol. 23, 72�??77 (1972).
  122. A. Conner, M. Nagaoka, J. W. Rowe, D. Perlman. Appl. Environ. Microbiol. 32, 310�??311 (1976).
  123. L. G. Parks, C. S. Lambright, E. F. Orlando, L. J. Guillette, G. T. Ankley, L. E. Gray. Toxicol. Sci.
    62, 257�??267 (2001).
  124. A. L. Edwards, R. L. Jenkins, L. J. Davenport, J. A. Duke. Economic Botany 56, 204�??206 (2002).
  125. V. S. Wilson, C. Lambright, J. Ostby, L. E. Gray. Toxicol. Sci. 70, 202�??211 (2002).
  126. C. Potera. Environ. Health Perspect. 108, A446 (2000).
  127. S. Y. Euling and C. A. Kimmel. Sci. Total Environ. 274, 103�??113 (2001).
  128. C. J. Wolf, G. A. LeBlanc, J. S. Ostby, L. E. Gray. Toxicol. Sci. 55, 152�??161 (2000).
  129. S. Y. Euling, C. Gennings, E. M. Wilson, J. A. Kemppainen, W. R. Kelce, C. A. Kimmel. Toxicol.
    Sci. 69, 332�??343 (2002).

Damn it all! And after I went to such lengths to try and format it into easy reading. Damn word wrap function.

lol and just the other day I was talking to my phys teacher about androgen receptors.

He has his phd and is a researcher at UC Irvine. He asked if I meant dealing with AR in essence to AAS use. I was like “uhhhh no?” lol Now the whole class looks at me funny.

Good read, thanks Aragorn.

Gerdy

Rofl. You probably shouldn’t have mentioned that in public. Now you’ll never be free of the stigma!

Or you could just stare back at them. Tap your veins with your fingers and ask them if they’ve got a rubberband…

They’ll never get the joke, but you might scare the living daylights out of one or two of them. Damn dirty smack steroid addicts.

by phys you mean physics teacher right? How’s he a physics teacher if he has a biochem/chem degree?

This post was flagged by the community and is temporarily hidden.

[quote]AlteredState wrote:
I think DG means physiology lecturer.

I had a similar event to DG’ public gaffe, when I tried to explain the easy availability of rHGH. The teacher thought it was still extracted from cadaveric pituitary glands.

I explained that it was now made from e.coli strains and could be bought over the internet.

I also explained about hyperplasia Vs acromegaly, only to realise the entire class was looking at me aghast, lol.[/quote]

yea physiology. I had another one in my anatomy class when my teacher was talking about steroids and mentioned that “once testosterone is suppressed we have no way of bringing the hormones back to homeostasis, also there is no way to combat the sides from increased estrogen”

I then explained how there is things that assist in bringing the body back to homeostasis and then asked her what she knew about aromatase inhibitors.

yea the whole class was staring and it wasn’t the same since…although everybody came to me to study when we were in the endocrine system :stuck_out_tongue: lol

I actually really like this new physiology prof…i’m really intrigued at how he gets paid to do some research and tests that sound fun. lol I’m really thinking about just grinding out a phd and trying to get his job.

A prof with a phd who is active in research at a major university in california makes bank! Plus I could specify which kind of research I would like to work in, I’m leaning towards endocrinolgy, neurology, or whatever the ology is for mucular diseases. lol

DG

[quote]Dirty Gerdy wrote:
lol and just the other day I was talking to my phys teacher about androgen receptors.

He has his phd and is a researcher at UC Irvine. He asked if I meant dealing with AR in essence to AAS use. I was like “uhhhh no?” lol Now the whole class looks at me funny.

Good read, thanks Aragorn.

Gerdy[/quote]

You have been marked!!! You have to wear your band with the snake and arrow around your arm now (think nazi germany and jews with star of david bands) I had the a similar experience in an intro anatomy class.

When we covered the endocrine system the teacher decided to be a smarty pants and offer his wisdom on the evils of steroids. “Steroid use disrups the bodys blah blah” They cause cancer. He went on and on until I said enough. I had to defend the noble hormone.

I had to defend my bretheren. We duked it out for a while regarding the use of PCT and AI admin. in order to control aromatization. He tried to one up me when he said that the use of oral steroids cause cancerous tumors in the liver.

I replied, “Show me a clinical study” The whole class looked at me like I was leper. He kinda of just stood there. Well they do regardless he wanted to say. Stupid shit packing right winger. I knew I could of made Rainjack proud that day sniff.

I knew that was so, because when I left the class I heard his hammer ring in the heavens, in the holyland of Asgard.

From deep within the halls of Valhalla his hammer rang all the way towards our realm. rofl!

[quote]Growing_Boy wrote:
Dirty Gerdy wrote:
lol and just the other day I was talking to my phys teacher about androgen receptors.

He has his phd and is a researcher at UC Irvine. He asked if I meant dealing with AR in essence to AAS use. I was like “uhhhh no?” lol Now the whole class looks at me funny.

Good read, thanks Aragorn.

Gerdy

You have been marked!!! You have to wear your band with the snake and arrow around your arm now (think nazi germany and jews with star of david bands) I had the a similar experience in an intro anatomy class.

When we covered the endocrine system the teacher decided to be a smarty pants and offer his wisdom on the evils of steroids. “Steroid use disrups the bodys blah blah” They cause cancer. He went on and on until I said enough. I had to defend the noble hormone.

I had to defend my bretheren. We duked it out for a while regarding the use of PCT and AI admin. in order to control aromatization. He tried to one up me when he said that the use of oral steroids cause cancerous tumors in the liver.

I replied, “Show me a clinical study” The whole class looked at me like I was leper. He kinda of just stood there. Well they do regardless he wanted to say. Stupid shit packing right winger. I knew I could of made Rainjack proud that day sniff.

I knew that was so, because when I left the class I heard his hammer ring in the heavens, in the holyland of Asgard.

From deep within the halls of Valhalla his hammer rang all the way towards our realm. rofl! [/quote]

HAHAHAHA! lmao!!!

I’ve found that teachers really don’t like it when you ask them to prove some of the stuff that they are teaching you, especially when some is opinionated. They expect us to agree with, and accept that everything they say is correct. With some teachers I think I could have taught the class better…oh well…life I guess. lol

DG

This post was flagged by the community and is temporarily hidden.

Damn stupid profs. My biochemistry professor and major prof, who of ALL people should know better because he’s a hardcore biophysical biochemistry guy and protein scientist, shot off some of the most retarded exercise and steroid nonsense I’d ever heard.

WHY is it that otherwise brilliant people who should know better shut their brain off when the subject is exercise or steroids?

I simply refuse to listen to someone talking about steroid use when they are blatantly ignorant on the subject. When I talk to my local guru, I feel like a pupil to Socrates but when a 160lb at 20%BF skinny fat, “I used to be a surfer and in real good shape but I injured my self big wave surfing” excuse using bitch of a man tries to tell me otherwise I want to tear said person’s head off.

I was tragically watching the news a while back talking about the new evil weight loss drug…Clenbuterol or “Clen” among “heavy users”. The skinny fat bitch doing the story went on about how its a veterinary drug and how some celebrities use it to get ready for a video or awards show. They made it sound like if it was crack.

Well it is if you stack with ephedrine but thats not the point. This distribution of fecal matter quality information regarding the “EVILS” of steroids is all linked back to the media blowing idiots mistakes linked to AAS out of proportion. “He died not of depression (drawn out pause to build fear and suspense) but from steroids” Motherfucking bullshit. I need to stop now or I’ll start ranting.

lol I was telling my family why my cousin was taking an EC stack leading up to a bodybuilding show and they all told me “you have him on meth, that’s all that is” I then tried to explain that methamphetamine is still different than ephedra although they are real similar…i would have been better off banging my head on the wall, but whatever me and my cousin are both 20 and living on our own so we can take what we want. My family thinks I’m an evil PED addict and will rage out on everybody and the fact still is that I’m natural and they don’t believe me. lol

My dad finds the drugs intriguing and trusts me and my knowledge, he likes hearing about them and that’s kind of cool.

He is actually mid 40’s with a kidney transplant, I want to see if he will try and qualify for trt and hgh replacement therapy. If he could score those scripts by his doc I’d be in it to win it! lol :wink: jk

what do you guys think?

sorry for the hijack aragorn on androgen receptors, and sorry to all for the weird off track post lol

DG

[quote]Dirty Gerdy wrote:
lol I was telling my family why my cousin was taking an EC stack leading up to a bodybuilding show and they all told me “you have him on meth, that’s all that is” I then tried to explain that methamphetamine is still different than ephedra although they are real similar…i would have been better off banging my head on the wall, but whatever me and my cousin are both 20 and living on our own so we can take what we want. My family thinks I’m an evil PED addict and will rage out on everybody and the fact still is that I’m natural and they don’t believe me. lol

My dad finds the drugs intriguing and trusts me and my knowledge, he likes hearing about them and that’s kind of cool.

He is actually mid 40’s with a kidney transplant, I want to see if he will try and qualify for trt and hgh replacement therapy. If he could score those scripts by his doc I’d be in it to win it! lol :wink: jk

what do you guys think?

sorry for the hijack aragorn on androgen receptors, and sorry to all for the weird off track post lol

DG[/quote]

True that! sorry Aragorn

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[quote]AlteredState wrote:
Dirty Gerdy wrote:
lol I was telling my family why my cousin was taking an EC stack leading up to a bodybuilding show and they all told me “you have him on meth, that’s all that is” I then tried to explain that methamphetamine is still different than ephedra although they are real similar…i would have been better off banging my head on the wall, but whatever me and my cousin are both 20 and living on our own so we can take what we want. My family thinks I’m an evil PED addict and will rage out on everybody and the fact still is that I’m natural and they don’t believe me. lol

My dad finds the drugs intriguing and trusts me and my knowledge, he likes hearing about them and that’s kind of cool.

He is actually mid 40’s with a kidney transplant, I want to see if he will try and qualify for trt and hgh replacement therapy. If he could score those scripts by his doc I’d be in it to win it! lol :wink: jk

what do you guys think?

sorry for the hijack aragorn on androgen receptors, and sorry to all for the weird off track post lol

DG

I think that Aragorn should beat you up for ruining his thread.

J/K. I think you should draw a comparison between aspirin (or codiene) and morphine, next time they compare eph with meth.

I think that whatever makes you old man feel happy, iwithout[/i] any outside pressure or stigma from the rest of his familly, would be a good thing.[/quote]

shoot he’d be down to take it, but I was thinking more along the lines of getting some stuff that could transfer over into my bodybuilding supplementation :stuck_out_tongue_winking_eye: lol

Gerdy