Testis abnormalities in neonatally DES-exposed rats

Induction of reproductive tract developmental abnormalities in the male rat by lowering androgen production or action in combination with a low dose of diethylstilbestrol: evidence for importance of the androgen-estrogen balance

2002 Study Abstract

This study tested the hypothesis that testis/reproductive tract abnormalities induced in the rat by neonatal treatment with diethylstilbestrol (DES) result from disturbance of the androgen-estrogen balance. Male rats were treated neonatally with a dose of DES (0.1 micro g) that induced either no or small effects on its own or with a dose (10 micro g) that induced major reproductive tract abnormalities.

To allow quantification, the abnormalities chosen for study were distension of the rete testis and efferent ducts and reduction in epithelial cell height in the efferent ducts and vas deferens.

To alter the androgen-estrogen balance, other rats were treated with DES (0.1 micro g) in combination with a treatment to suppress either androgen production [GnRH antagonist (GnRHa)] or androgen action (flutamide); other rats were treated with GnRHa or flutamide alone. Testosterone levels were measured to verify the effects of treatment.

Combined administration of DES (0.1 micro g) plus GnRHa or flutamide induced significantly greater distension/overgrowth of the rete testis and efferent ducts (ED) and a reduction in epithelial cell height of the ED than did DES (0.1 micro g) administered alone. Neither GnRHa nor flutamide affected rete or ED distension when administered alone, but both significantly reduced ED epithelial cell height. Neonatal treatment with bisphenol-A (100 micro g) with or without GnRHa had no significant effect on any of these parameters. In contrast to the ED, a reduction in cell height of the vas deferens was induced to an equal extent by DES (10 micro g), DES (0.1 micro g) with GnRHa, and GnRHa alone, suggesting greater sensitivity of this tissue to both androgen and estrogen action. The induction of major abnormalities in rats treated with DES (10 micro g) was coincident with loss of androgen receptor immunoexpression in affected tissues. Reduced androgen receptor immunoexpression was also induced by combined treatment with DES (0.1 micro g) plus GnRHa or flutamide, whereas treatment with any of these compounds alone had no or only minor effects.

These findings suggest that reduced androgen action sensitizes the reproductive tract to estrogens, demonstrating that the balance in action between androgens and estrogens, rather than their absolute levels, may be of fundamental importance in determining normal or abnormal development of some regions of the male reproductive tract.

Discussion

The primary aim of the present studies was to test the hypothesis that testis/reproductive tract abnormalities, which are induced in the neonatal rat by treatment with relatively high doses (10 μg) of DES, result from disturbance of the androgen-estrogen balance rather than from the estrogenic effect of DES alone (23, 24). This was tested by treating male rats neonatally with a dose of DES (0.1 μg) that induced either no or small effects on its own and combining this with a treatment that suppressed either androgen production (GnRHa) or androgen action (the androgen receptor antagonist flutamide). The results show unequivocally that either of these combined treatments was able to significantly induce greater abnormalities of the rete testis and efferent ducts than did 0.1 μg DES administered alone. Neither GnRHa nor flutamide induced any of the abnormalities when administered alone, whereas treatment with a high dose of DES (10 μg) induced major abnormalities coincident with loss of immunoexpression of the AR in affected tissues. Reduced immunoexpression of AR was also induced by combined treatment with 0.1 μg DES and GnRHa or flutamide, whereas treatment with any of the compounds alone had no or only minor effects on AR immunoexpression. These results together with our previous demonstration that induction of reproductive abnormalities by neonatal treatment with 10 μg DES can be blocked by cotreatment with testosterone (24) provide support for the suggestion that these abnormalities result from a disturbance of the normal androgen-estrogen balance rather than from a lowering of androgen action or an elevation of estrogen action per se. A slightly alternative view is that the level of androgen exposure determines the sensitivity of the developing male reproductive tract to estrogens, such that low androgen levels increase sensitivity to estrogens and vice versa. Either interpretation implies that normal or abnormal development of the male reproductive system may be governed by the relative levels (balance) of androgens and estrogens rather than by the absolute level of either hormone. This has several implications, as discussed below.

The finding of key importance from the present study is the demonstration that combined treatment with a relatively low dose (0.1 μg) of DES plus treatments to either lower androgen production (GnRHa) or block androgen action (flutamide) was able to induce significantly greater distension of the rete testis or efferent ducts, as measured by lumenal area, than any of the treatments administered alone; of the latter, only 0.1 μg DES had any (minor) effect on its own. Although these contrasting effects were clear-cut, the use of another end point, epithelial cell height in the efferent ducts or proximal vas deferens, resulted in a more complex picture, as all single treatments other than bisphenol-A exerted significant adverse effects. In the efferent ducts it was still clear that combined treatment with 0.1 μg DES plus either GnRHa or flutamide was able to reduce epithelial cell height to a significantly greater extent than any of these treatments individually; indeed, the combined treatments caused an effect of similar magnitude to that induced by treatment with 10 μg DES alone. In contrast, several of the individual treatments (10 or 0.1 μg DES plus GnRHa) induced very similar effects on epithelial cell height in the proximal vas deferens, and combined treatment with 0.1 μg DES and either GnRHa or flutamide was unable to exacerbate this effect compared with administration of 0.1 μg DES or GnRHa alone. This suggests that more posterior parts of the reproductive tract, such as the vas deferens, may be more sensitive to androgens and estrogens than the more anterior parts (rete and efferent ducts) such that all single treatments, other than flutamide and bisphenol-A, induced maximal effects. This makes it fundamentally difficult to test whether the androgen-estrogen balance is as important in the vas as it appears to be in the more anterior regions of the tract.

Although the different responses of epithelial cells from the efferent ducts and vas deferens to altered androgens and estrogens remain to be explained, the fact that normal development of the rete and efferent ducts appear particularly dependent on a normal androgen-estrogen balance may have relevance to findings in ERα knockout (ERKO) mice. The latter exhibit distension of both the rete and efferent ducts in the face of supranormal testosterone levels and the absence of normal expression of ERα in the epithelium of both the rete and efferent ducts. This raises the possibility that the abnormalities reported in ERKO males do not result only from the loss of ERα-mediated estrogen action, but might also be affected by disturbance of the androgen-estrogen balance, although in the opposite direction (supranormal androgen plus subnormal estrogen action) to that induced in the present studies. However, this would fail to explain why aromatase knockout mice, which also have elevated testosterone levels, do not show the same structural abnormalities as ERKO mice. Nevertheless, the present findings caution that whenever androgen and/or estrogen levels are altered substantially from normal in the developing male, changes resulting from disruption of the androgen-estrogen balance should be kept in mind.

There are examples in the literature indicating a role for the androgen-estrogen balance. For example, gynecomastia in men can be induced either by raising estrogen levels or by lowering androgen levels, such that in either situation the androgen-estrogen balance is altered in favor of estrogens. Another example is clover disease, in which castrated rams that fed on Mediterranean clover containing weakly estrogenic phytoestrogens died from urinary retention due to overgrowth of the bulbo-urethral glands, which are both an estrogen and an androgen target. Intact rams or castrated rams treated with androgens and fed on the same clover showed no overgrowth or ill effects. Thus, in castrated rams with low androgen levels, phtyoestrogens induced a catastrophic effect, whereas in intact rams with high androgen levels or in castrated rams supplemented with androgens, no effect occurred despite exposure to the same “estrogen” level. In many respects this example arises from a situation in which hormonal status would be comparable to that induced in the present studies by combined treatment with 0.1 μg DES plus GnRHa. There may be other examples in which a role for altered androgen-estrogen balance could be important. For example, abnormal prostatic structure and growth induced by neonatal estrogen treatment are known to involve both altered androgen and estrogen action, and this may apply also to reproductive tissues in the female.

If the relative, rather than absolute, levels of androgens and estrogens are important for normal development and/or function of the testis and reproductive tract, as our findings suggest, how would this work at the cellular level, given that the present understanding is that androgens and estrogens act via separate, if related, signaling systems? There are various possibilities based on published data, although none has been shown to operate physiologically. For example, estrogens can trans-activate the AR/ARA70 complex at high concentrations and thus activate the transcription of androgen-dependent genes, although DES could not exert this effect. Interaction between the C-terminal domain of ERα and the AR has been demonstrated using two-hybrid systems, and cotransfection of the two receptors into CV-1 cells has demonstrated a mutual ability of each receptor to antagonize trans-activation mediated by ligand binding to the other receptor. An alternative explanation might be activation of the Src-Raf1/Shc-Erk2 pathway, in which androgens and estrogens may induce assembly of a novel ternary complex comprising the AR, ER (either ERα or ERβ), and Src. This complex triggers activation of the protein kinase domain of Src and downstream effects, such as cell proliferation or inhibition of apoptosis. The androgen-AR and estrogen-ER complexes bind to separate domains on the Src protein, and antagonists of either the AR or ER can block activation of this pathway by either androgens or estrogens. Our recent findings that expression of classical androgen-regulated genes in the prostate can also be regulated by estrogens and that antiestrogens can block androgen activation of these genes in vivo are consistent with the activation of such a pathway.

Regardless of the pathway involved, the present findings have implications for issues such as endocrine disruptors, in which considerations of risk are focused largely on the absolute dose/level of exposure as opposed to the relative levels of androgen and estrogens. The present study has shown that combined treatment with a weak environmental estrogen, bisphenol-A, plus a GnRHa was unable to induce any of the abnormalities induced by 0.1 μg DES plus GnRHa, suggesting that in this situation the estrogenicity of the bisphenol-A, when injected in moderately high amounts (100 μg/injection), was still insufficient to perturb the androgen-estrogen balance. Whether this balance can be disturbed by higher doses of this or other environmental estrogens or in combination with environmental antiandrogens are obvious questions that need to be addressed.

In summary, the present findings add to the growing evidence of a close interrelationship between the actions of androgens and estrogens in regulating normal and abnormal development of the male reproductive system. Our findings suggest that the balance in action between androgens and estrogens, rather than the absolute levels of either hormone, may be of fundamental importance at least for some regions of the reproductive tract. From a physiological perspective, local regulation of relative levels of androgens and estrogens, for example by differential expression of aromatase or 5α-reductase, may be critical factors that ensure an appropriate steroid milieu for specific regions of the reproductive system

References

  • Full study (free access) : Induction of reproductive tract developmental abnormalities in the male rat by lowering androgen production or action in combination with a low dose of diethylstilbestrol: evidence for importance of the androgen-estrogen balance, Endocrinology, Volume 143, Issue 12, Pages 4797–4808, doi.org/10.1210/en.2002-220531, 01 December 2002.
  • Featured image credit forum.phish.net.
DES DIETHYLSTILBESTROL RESOURCES

Testicular cancer in prenatally DES-exposed men

Environmental Signaling: What Embryos and Evolution Teach Us About Endocrine Disrupting Chemicals, 2001

Abstracts

DES as a model for developmental estrogenization

Studies in our laboratory and others have helped to define a phenotype typical of male mice exposed in utero to DES and other estrogens. The structural or functional changes associated with the phenotype include undescended testes, cysts of the epididymis, prostatic lesions, distended seminal vesicles, retained Müllerian ducts, reduced fertility, and abnormal spermatogenesis (even in a scrotal testis).

In a smaller number of cases, the occurrence of testicular cancers was noted (see 1979 study, 1985 study, 1986 study). The severity of these changes was dose-dependent as were the appearance of all the lesions in the suite. It was subsequently shown that the epididymal cysts were of Müllerian duct origin; it was apparent that the enlarged prostatic utricle was also the Müllerian contribution to the prostate gland.

Features in the human male

Genital tract defects similar to those seen in DES-treated mice were also observed in men whose mothers had taken DES (study).

A group at the University of Chicago reported that DES-exposed men had a higher incidence of undescended (cryptorchid) testes and epididymal cysts than comparable unexposed men. Gill and colleagues (study) went on to confirm and extend these studies and showed, in addition, a higher incidence of hypoplastic testes and abnormal sperm.

In one study reporting testicular cancer in one DES-exposed man, the possibility of cancer of the testis as a result of prenatal exposure to DES was raised by Gill et al. (study). A few other case reports of testicular cancer (seminoma) and epididymal cysts in prenatally DES-exposed men have been reported (study).

References

  • Environmental Signaling: What Embryos and Evolution Teach Us About Endocrine Disrupting Chemicals, Endocrine Reviews, Volume 22, Issue 3, Pages 319–341 doi.org/10.1210/edrv.22.3.0432, 01 June 2001.
DES DIETHYLSTILBESTROL RESOURCES

Adenocarcinoma of the rete testis

Diethylstilbestrol-induced lesions of the mouse rete testis, 1986

Abstract

The induction of a lesion resembling carcinoma in the rete testis of male mice provides a useful model for study of the pathogenesis of hormonally induced lesions of the testis and possibly other developmental neoplasms.

The model should be of further use in alerting the clinician to the possibility of rete testis changes in the DES-exposed patient. Also, the extreme rarity of this lesion in both experimental animals and humans has made study of the general cytologic features of this neoplasm difficult; studies of the pathogenesis of the lesion are unknown.

The relatively large number of hyperplasias and adenocarcinomas of the rete testes in DES-treated mice provides new possibilities for such investigations.

While no reports of rete hyperplasia or adenocarcinoma in humans have been attributed to prenatal exposure to DES, three cases of seminoma have been described in prenatally DES-exposed men, suggesting an association of prenatal DES treatment with subsequent development of testicular tumors (1979 study and 1983 study).

A recent report states that rete adenocarcinoma can be misdiagnosed as seminoma, and seminoma must be ruled out before a diagnosis of rete adenocarcinoma can be made. Thus, caution should be taken in diagnosing any testicular lesions associated with prenatal DES exposure.

References

  • Adenocarcinoma of the rete testis. Diethylstilbestrol-induced lesions of the mouse rete testis, The American journal of pathology, NCBI PubMed PMC1888460, 1986 Dec.
  • Featured image apcf.infosite.ust.hk.
DES DIETHYLSTILBESTROL RESOURCES

Testicular cancer case in a DES Son

Seminoma and Epididymal Cysts in a Young Man With Known Diethylstilbestrol Exposure In Utero, 1983

Abstract

Exposure of women to diethylstilbestrol in utero has been linked to the development of adenosis and clear cell adenocarcinoma of the vagina.

A variety of male genital tract abnormalities, including epididymal cysts, maldescended testes, hypoplastic testes, varicoceles, and spermatozoal defects, occur with increased incidence in men exposed to diethylstilbestrol in utero.

Testicular tumors occur in adult mice given diethylstilbestrol, and preneoplastic testicular changes have been described in mice exposed prenatally to diethylstilbestrol. The possibility of carcinogenesis has been suggested in diethylstilbestrol-exposed males, but, to our knowledge, until now no case of testicular cancer has been documented in a person exposed in utero to diethylstilbestrol.

We report a seminoma and ipsilateral epididymal cysts in a 28-year-old man with known diethylstilbestrol exposure.

References

DES DIETHYLSTILBESTROL RESOURCES

Reproductive tract lesions in male mice exposed prenatally to DES

DES Sons should be further evaluated for latent alterations of the genital tract, 1975

Abstracts

Sixty percent of the male offspring from pregnant mice treated with diethylstilbestrol during gestation were sterile. The affected animals had gonadal changes which included intra-abdominal or fibrotic testes, or both. Additionally, nodular masses in the ampullary region of the reproductive tract were observed in 6 of 24 animals; one of these appeared to be preneoplastic.

… “Eight animals had epididymal cysts; six of these also had testicular lesions.” …

… “In light of these results in rodents, the incidence of cryptorchidism in young boys whose mothers had been treated with DES during gestation may be of clinical importance. Obviously, these offspring should be further evaluated for latent alterations of the genital tract, since changes in the adult male human reproductive tract similar to those we observed in the mouse might be dismissed as secondary to inflammation. Some of these lesions could be important causes of infertility even when viable sperm are produced.” …

References

  • Reproductive tract lesions in male mice exposed prenatally to diethylstilbestrol, Science, NCBI PubMed, PMID: 242076, 1975 Dec 5.
  • Featured image credit quantamagazine.
DES DIETHYLSTILBESTROL RESOURCES

Prenatal DES treatment and subsequent development of testicular tumors

Lesions of the rete testis in mice exposed prenatally to diethylstilbestrol, 1985

Abstract

Adenocarcinoma of the rete testis is an exceptionally rare and malignant testicular neoplasm.

Although treatment of pregnant women with diethylstilbestrol (DES) results in reproductive tract abnormalities in their male offspring, increased incidence of testicular tumors has not been verified. However, recently three cases of seminoma have been described in men prenatally exposed to DES, suggesting an association of prenatal DES treatment and the subsequent development of testicular tumors.

This report describes the treatment of outbred pregnant CD-1 mice with DES (100 micrograms/kg) on Days 9 through 16 of gestation and its effects on their male offspring.

In addition to nonmalignant abnormalities such as retained testes which have been reported in men exposed prenatally to DES, lesions resembling adenocarcinoma of the rete testis were seen in prenatally DES-treated mice at 10 to 18 mo of age (11 of 233; 5%). No comparable lesions were seen in 96 age-matched control male mice.

These results suggest an association of prenatal DES exposure and the subsequent development of testicular lesions in the rete testis of mice.

References

  • Lesions of the rete testis in mice exposed prenatally to diethylstilbestrol, Cancer research, NCBI PubMed PMID: 4027990, 1985 Oct.
  • Featured image credit the guardian.
DES DIETHYLSTILBESTROL RESOURCES

Testicular dysgenesis syndrome

Possible role of endocrine disrupters, 2006

Abstracts

The testicular dysgenesis syndrome (TDS) hypothesis proposes that the four conditions cryptorchidism, hypospadias, impaired spermatogenesis and testis cancer may all be manifestations of disturbed prenatal testicular development. The TDS hypothesis is based on epidemiological, clinical and molecular studies, all suggestive of an interrelation between the different symptoms. The aetiology of TDS is suspected to be related to genetic and/or environmental factors, including endocrine disrupters.

…Important insight into the effect of in utero exposure to compounds with oestrogenic activity in humans comes from the former widespread use of diethylstilboestrol (DES), a synthetic oestrogen. …
… The effect of DES on sperm concentration and risk of development of testis cancer is unclear, as some studies have found a reduced sperm concentration in men exposed to DES in utero, whereas others have not. For testis cancer, only a slight increase in risk has been cautiously suggested (1996), (2001). …

Few human studies have found associations/correlations between endocrine disrupters, including phthalates, and the different TDS components. However, for ethical reasons, evidence of a causal relationship between prenatal exposure and TDS is inherently difficult to establish in human studies, rendering the recently developed animal TDS model an important tool for investigating the pathogenesis of TDS. Clinically, the most common manifestation of TDS is probably a reduced sperm concentration, whereas the more severe form may include a high risk of testis cancer. Clinicians should be aware of the interconnection between the different features of TDS, and inclusion of a programme for early detection of testis cancer in the management of infertile men with poor semen quality is recommended.

References

  • Testicular dysgenesis syndrome: possible role of endocrine disrupters, Best practice & research. Clinical endocrinology & metabolism, NCBI PubMed PMID: 16522521, 2006 Mar.
DES DIETHYLSTILBESTROL RESOURCES

Cancer risk in men exposed in utero to diethylstilbestrol

DES Sons’ (increased) cancer risk, 2001

Abstracts

BACKGROUND
An association between prenatal diethylstilbestrol (DES) exposure and cancer in men, especially testicular cancer, has been suspected, but findings from case-control studies have been inconsistent. This study was conducted to investigate the association between prenatal DES exposure and cancer risk in men via prospective follow-up.

METHODS
A total of 3613 men whose prenatal DES exposure status was known were followed from 1978 through 1994. The overall and site-specific cancer incidence rates among the DES-exposed men were compared with those of the unexposed men in the study and with population-based rates. The relative rate (RR) was used to assess the strength of the association between prenatal DES exposure and cancer development. All statistical tests were two-sided.

RESULTS
Overall cancer rates among DES-exposed men were similar to those among unexposed men (RR = 1.07; 95% confidence interval [CI] = 0.58 to 1.96) and to national rates (RR = 0.99; 95% CI = 0.65 to 1.44). Testicular cancer may be elevated among DES-exposed men, since the RRs for testicular cancer were 3.05 (95% CI = 0.65 to 22.0) times those of unexposed men in the study and 2.04 (95% CI = 0.82 to 4.20) times those of males in the population-based rates. The higher rate of testicular cancer in the DES-exposed men is, however, also compatible with a chance observation.

CONCLUSIONS
To date, men exposed to DES in utero do not appear to have an increased risk of most cancers. It remains uncertain, however, whether prenatal DES exposure is associated with testicular cancer.

References

  • Cancer risk in men exposed in utero to diethylstilbestrol, Journal of the National Cancer Institute, NCBI PubMed PMID: 11287449, 2001 Apr.
  • Featured image Harshil Gudka.
DES DIETHYLSTILBESTROL RESOURCES

DES-induced Testis Cancer

Male reproductive health and environmental xenoestrogens, 1996

Abstracts

Incidence of Testicular Cancer

Testicular cancer is now the most common malignancy of young men in many countries; and although it is still rare compared to the malignant diseases most prevalent in old age, the lifetime risk of developing testicular cancer now approaches 1% in a country such as Denmark. The incidence of testicular cancer has increased for several decades.

Risk factors for testicular cancer have been analyzed in several case-control studies. Estrogen treatment of mothers whose sons have developed testicular cancer has remained an equivocal risk factor. It is unfortunate that there are no prospective studies yet concerning the testicular cancer risk among males exposed to DES.

The effect of DES on risk of development of testis cancer seems to be unclear; only a slight increase in risk has been cautiously suggested.

Occurrence of Abnormalities in the Reproductive System of the Sons of Women Exposed to Diethylstilbestrol during Pregnancy

Summary

Exposure to DES during pregnancy results in an increased risk for several male reproductive disorders, such as cryptorchidism, urethral abnormalities, epididymal cysts, and testicular hypoplasia. In addition, the semen quality of DES sons is worse than that of controls. Incidence of testicular cancer is approximately doubled among DES sons compared to the general population, but whether this represents a true increase of the cancer risk is equivocal.

Effects of Synthetic Estrogens on the Testis in Animal Models

Summary

Diethylstilbestrol treatment of experimental animals in utero results in increased incidence of cryptorchidism; urethral abnormalities; testicular hypoplasia; poor semen quality; and infertility, abnormalities in accessory sex organs, rete testis adenocarcinoma, interstitial cell hyperplasia, and tumors. Thus, the outcome of DES exposure of experimental animals is highly analogous to the findings in humans.

References

  • Full study (free access) : Male reproductive health and environmental xenoestrogens, Environmental Health Perspectives, NCBI PubMed PMC1469672, 1996 Aug.
  • Featured image clevelandclinic.
DES DIETHYLSTILBESTROL RESOURCES

DES-induced vascular risk

Immunogenicity of synthetic sex hormones and thrombogenesis, 1985

Study Abstract

The ingestion of synthetic steroidal and non-steroidal estrogens may induce antiestrogen antibodies in women on oral contraceptives, and in prostatic patients treated with diethylstilbestrol (DES). Natural sex hormones have no such effect.

A radioimmunoassay with tritiated ethinylestradiol or DES was applied to study the prevalence of synthetic sex hormone antibodies in 2 populations: 100 women on estroprogestative hormones and 93 cases of DES treated prostatic cancers. Homologous non-treated controls were compared.

Results allowed to identify among treated and asymptomatic subjects an immunoreactive population of 30% women and 47% men. Furthermore, the antibodies were found with a much higher frequency (p less than 0.001) in patients who had experienced a thromboembolic disease while on treatment: 90% of women and 74% of men.

The importance of these antibodies as a risk factor, their possible role in promoting vascular lesions, the interest of their detection for the prevention of the vascular risk induced by synthetic sex hormones, are considered.

References

DES DIETHYLSTILBESTROL RESOURCES