Long-Term Exposure to Neonicotinoid Insecticide Acetamiprid at Environmentally Relevant Concentrations Impairs Endocrine Functions in Zebrafish: Bioaccumulation, Feminization, and Transgenerational Effects

Neonicotinoid insecticides have attracted worldwide attention due to their ubiquitous occurrence and detrimental effects on aquatic organisms, yet their impacts on fish reproduction during long-term exposure remain unknown. Here, zebrafish (F0) were exposed to a neonicotinoid, acetamiprid, at 0.19-1637 μg/L for 154 d. Accumulation and biotransformation of acetamiprid were observed in adult fish, and the parent compound and its metabolite (acetamiprid-N-desmethyl) were transferred to their offspring. Acetamiprid caused slight survival reduction and significant feminization in F0 fish even at the lowest concentration. Hormone levels in F0 fish were remarkedly altered, that is, gonad 17β-estradiol (E2) significantly increased, while androstenedione decreased. The corresponding transcription of steroidogenic genes (ar, cyp19b, fshβ, gnrh2, gnrh3, and lhβ) were significantly upregulated in the brain and gonad of the females but downregulated in the males. The vtg1 gene expression in the liver of male fish was also upregulated. In addition to F0 fish, parental exposure to acetamiprid decreased hatchability and enhanced malformation of F1 embryos. Chronic exposure to acetamiprid at environmentally relevant concentrations altered hormone production and the related gene expression of the hypothalamic-pituitary-gonad (HPG) axis in a sex-dependent way, caused feminization and reproductive dysfunction in zebrafish, and impaired production and development of their offspring.

Gene Expression of Takifugu rubripes Gonads During AI- or MT-induced Masculinization and E2-induced Feminization

Elucidating the global molecular changes that occur during aromatase inhibitor (AI)- or 17α-methyltestosterone (MT)-induced masculinization and estradiol-17β (E2)-induced feminization is critical to understanding the roles that endocrine and genetic factors play in regulating the process of sex differentiation in fish. Here, fugu larvae were treated with AI (letrozole), MT, or E2 from 25 to 80 days after hatching (dah), and gonadal transcriptomic analysis at 80 dah was performed. The expression of dmrt1, gsdf, foxl2, and other key genes (star, hsd3b1, cyp11c1, cyp19a1a, etc.) involved in the steroid hormone biosynthesis pathway were found be altered. The expression of dmrt1, gsdf, cyp19a1a, and foxl2 was further verified by quantitative polymerase chain reaction. In the control group, the expression of dmrt1 and gsdf was significantly higher in XY larvae than in XX larvae, while the expression of foxl2 and cyp19a1a was significantly higher in XX larvae than in XY larvae (P < .05). AI treatment suppressed the expression of foxl2 and cyp19a1a, and induced the expression of dmrt1 and gsdf in XX larvae. MT treatment suppressed the expression of foxl2, cyp19a1a, dmrt1, and gsdf in XX larvae. E2 treatment suppressed the expression of dmrt1 and gsdf, but did not restore the expression of foxl2 and cyp19a1a in XY larvae. The shared response following AI, MT, and E2 treatment suggested that these genes are essential for sex differentiation. This finding offers some insight into AI or MT-induced masculinization, and E2-induced femininization in fugu.

Castration delays epigenetic aging and feminizes DNA methylation at androgen-regulated loci

In mammals, females generally live longer than males. Nevertheless, the mechanisms underpinning sex-dependent longevity are currently unclear. Epigenetic clocks are powerful biological biomarkers capable of precisely estimating chronological age and identifying novel factors influencing the aging rate using only DNA methylation data. In this study, we developed the first epigenetic clock for domesticated sheep (Ovis aries), which can predict chronological age with a median absolute error of 5.1 months. We have discovered that castrated male sheep have a decelerated aging rate compared to intact males, mediated at least in part by the removal of androgens. Furthermore, we identified several androgen-sensitive CpG dinucleotides that become progressively hypomethylated with age in intact males, but remain stable in castrated males and females. Comparable sex-specific methylation differences in MKLN1 also exist in bat skin and a range of mouse tissues that have high androgen receptor expression, indicating that it may drive androgen-dependent hypomethylation in divergent mammalian species. In characterizing these sites, we identify biologically plausible mechanisms explaining how androgens drive male-accelerated aging.

Effects of adult male rat feminization treatments on brain morphology and metabolomic profile

Body feminization, as part of gender affirmation process of transgender women, decreases the volume of their cortical and subcortical brain structures. In this work, we implement a rat model of adult male feminization which reproduces the results in the human brain and allows for the longitudinal investigation of the underlying structural and metabolic determinants in the brain of adult male rats undergoing feminization treatments. Structural MRI and Diffusion Tensor Imaging (DTI) were used to non-invasively monitor in vivo cortical brain volume and white matter microstructure over 30 days in adult male rats receiving estradiol (E₂), estradiol plus cyproterone acetate (CA), an androgen receptor blocker and antigonadotropic agent (E₂ + CA), or vehicle (control). Ex vivo cerebral metabolic profiles were assessed by ¹H High Resolution Magic Angle Spinning NMR (¹H HRMAS) at the end of the treatments in samples from brain regions dissected after focused microwave fixation (5 kW). We found that; a) Groups receiving E₂ and E₂ + CA showed a generalized bilateral decrease in cortical volume; b) the E₂ + CA and, to a lesser extent, the E₂ groups maintained fractional anisotropy values over the experiment while these values decreased in the control group; c) E₂ treatment produced increases in the relative concentration of brain metabolites, including glutamate and glutamine and d) the glutamine relative concentration and fractional anisotropy were negatively correlated with total cortical volume. These results reveal, for the first time to our knowledge, that the volumetric decreases observed in trans women under cross-sex hormone treatment can be reproduced in a rat model. Estrogens are more potent drivers of brain changes in male rats than anti-androgen treatment.

The shutting down of the insulin pathway: a developmental window for Wolbachia load and feminization

Using the isopod Armadillidium vulgare as a case study, we review the significance of the "bacterial dosage model", which connects the expression of the extended phenotype to the rise of the Wolbachia load. In isopods, the Insulin-like Androgenic Gland hormone (IAG) induces male differentiation: Wolbachia feminizes males through insulin resistance, presumably through defunct insulin receptors. This should prevent an autocrine development of the androgenic glands so that females differentiate instead: feminization should translate as IAG silencing and increased Wolbachia load in the same developmental window. In line with the autocrine model, uninfected males expressed IAG from the first larval stage on, long before the androgenic gland primordia begin to differentiate, and exponentially throughout development. In contrast in infected males, expression fully stopped at stage 4 (juvenile), when male differentiation begins. This co-occurred with the only significant rise in the Wolbachia load throughout the life-stages. Concurrently, the raw expression of the bacterial Secretion Systems co-increased, but they were not over-expressed relative to the number of bacteria. The isopod model leads to formulate the "bacterial dosage model" throughout extended phenotypes as the conjunction between bacterial load as the mode of action, timing of multiplication (pre/post-zygotic), and site of action (soma vs. germen).

Feminizing effects of exposure to Corexit-enhanced water-accommodated fraction of crude oil in vitro on sex determination in Alligator mississippiensis

Deepwater Horizon spilled over 200 million gallons of oil into the waters of the Gulf of Mexico in 2010. In an effort to contain the spill, chemical dispersants were applied to minimize the amount of oil reaching coastal shorelines. However, the biological impacts of chemically-dispersed oil are not well characterized, and there is a particular lack of knowledge concerning sublethal long-term effects of exposure. This study examined potential estrogenic effects of CWAF, Corexit 9500-enhanced water-accommodated fraction of oil, by examining its effect on estrogen receptors and sex determination in the American alligator, Alligator mississippiensis. The alligator exhibits temperature-dependent sex determination which is modulated by estrogen signals, and exposure to 17β-estradiol (E₂) and estrogenic compounds in ovo during the thermosensitive period of embryonic development can induce ovarian development at a male-producing temperature (MPT). CWAF induced transactivation up to 50% of the maximum induction by E₂ via alligator estrogen receptors in vitro. To determine potential endocrine-disrupting effects of exposure directly on the gonad, gonad-adrenal-mesonephric (GAM) organ complexes were isolated from embryos one day prior to the thermosensitive period and exposed to E₂, CWAF, or medium alone in vitro for 8-16 days at MPT. Both CWAF and E₂ exposure induced a significant increase in female ratios. CWAF exposure suppressed GAM mRNA abundances of anti-Müllerian hormone (AMH), sex determining region Y-box 9, and aromatase, whereas E₂ exposure suppressed AMH and increased Forkhead box protein L2 mRNA abundances in GAM. These results indicate that the observed endocrine-disrupting effects of CWAF are not solely estrogenically mediated, and further investigations are required.

Transgenic Chickens Overexpressing Aromatase Have High Estrogen Levels but Maintain a Predominantly Male Phenotype

Estrogens play a key role in sexual differentiation of both the gonads and external traits in birds. The production of estrogen occurs via a well-characterized steroidogenic pathway, which is a multistep process involving several enzymes, including cytochrome P450 aromatase. In chicken embryos, the aromatase gene (CYP19A1) is expressed female-specifically from the time of gonadal sex differentiation. Ectopic overexpression of aromatase in male chicken embryos induces gonadal sex reversal, and male embryos treated with estradiol become feminized; however, this is not permanent. To test whether a continuous supply of estrogen in adult chickens could induce stable male to female sex reversal, 2 transgenic male chickens overexpressing aromatase were generated using the Tol2/transposase system. These birds had robust ectopic aromatase expression, which resulted in the production of high serum levels of estradiol. Transgenic males had female-like wattle and comb growth and feathering, but they retained male weights, displayed leg spurs, and developed testes. Despite the small sample size, this data strongly suggests that high levels of circulating estrogen are insufficient to maintain a female gonadal phenotype in adult birds. Previous observations of gynandromorph birds and embryos with mixed sex chimeric gonads have highlighted the role of cell autonomous sex identity in chickens. This might imply that in the study described here, direct genetic effects of the male chromosomes largely prevailed over the hormonal profile of the aromatase transgenic birds. This data therefore support the emerging view of at least partial cell autonomous sex development in birds. However, a larger study will confirm this intriguing observation.

Short-term calorie restriction feminizes the mRNA profiles of drug metabolizing enzymes and transporters in livers of mice

Calorie restriction (CR) is one of the most effective anti-aging interventions in mammals. A modern theory suggests that aging results from a decline in detoxification capabilities and thus accumulation of damaged macromolecules. The present study aimed to determine how short-term CR alters mRNA profiles of genes that encode metabolism and detoxification machinery in the liver. Male C57BL/6 mice were fed CR (0, 15, 30, or 40%) diets for one month, followed by mRNA quantification of 98 xenobiotic processing genes (XPGs) in the liver, including 7 uptake transporters, 39 phase-I enzymes, 37 phase-II enzymes, 10 efflux transporters, and 5 transcription factors. In general, 15% CR did not alter mRNAs of most XPGs, whereas 30 and 40% CR altered over half of the XPGs (32 increased and 29 decreased). CR up-regulated some phase-I enzymes (fold increase), such as Cyp4a14 (12), Por (2.3), Nqo1 (1.4), Fmo2 (5.4), and Fmo3 (346), and numerous number of phase-II enzymes, such as Sult1a1 (1.2), Sult1d1 (2.0), Sult1e1 (33), Sult3a1 (2.2), Gsta4 (1.3), Gstm2 (1.3), Gstm3 (1.7), and Mgst3 (2.2). CR feminized the mRNA profiles of 32 XPGs in livers of male mice. For instance, CR decreased the male-predominantly expressed Oatp1a1 (97%) and increased the female-predominantly expressed Oatp1a4 (11). In conclusion, short-term CR alters the mRNA levels of over half of the 98 XPGs quantified in livers of male mice, and over half of these alterations appear to be due to feminization of the liver.

Feminizing adrenocortical carcinoma with selective suppression of follicle-stimulating hormone secretion and disorganized steroidogenesis: a case report and literature review

We report a 61-year-old male with gynecomastia, poor libido and erectile dysfunction. Endocrinological studies showed high levels of estradiol and dehydroepiandrosterone sulfate. Although luteinizing hormone (LH) level was within the normal limit, the concentration of follicle-stimulating hormone (FSH) was under the normal limit. Delayed response of LH and poor response of FSH to gonadotropin-releasing hormone administration were detected. Magnetic resonance imaging of the abdomen revealed a left adrenal tumor. Although the surgically-resected tumor was diagnosed as a high grade ACC based on Weiss's criteria of adrenocortical malignancy, no metastasis was detected. Since estrogen levels normalized after resection, feminizing ACC was confirmed. While LH concentration increased slightly after operation, FSH level became transiently elevated over the normal limit, and finally reached the normal range. These data may suggest that FSH was suppressed selectively by hormone produced by ACC different from estrogen.

Genetic feminization of the thoracic nervous system disrupts courtship song in male Drosophila melanogaster

Despite the growing research investigating the sex-specific organization of courtship behavior in Drosophila melanogaster, much remains to be understood about the sex-specific organization of the motor circuit that drives this behavior. To investigate the sex-specification of a tightly patterned component of courtship behavior, courtship song, the authors used the GAL4/UAS targeted gene expression system to feminize the ventral ganglia in male Drosophila and analyzed the acoustic properties of courtship song. More specifically, the authors used the thoracic-specifying teashirt promoter (tsh(GAL4)) to express feminizing transgenes specifically in the ventral ganglia. When tsh(GAL4) drove expression of transformer (tra), males were unable to produce prolonged wing extensions. Transgenic expression of an RNAi construct directed against male-specific fruitless (fru(M)) transcripts resulted in normal wing extension, but highly defective courtship song, with 58% of males failing to generate detectable courtship song. Of those that did sing, widths of individual pulses were significantly broader than controls, suggesting thoracic fru(M) function serves to mediate proprioceptive-dependent wing vibration damping during pulse song. However, the most critical signal in the song, the interpulse interval, remained intact. The inability to phenocopy this effect by reducing fru(M) expression in motor neurons and proprioceptive neurons suggests thoracic interneurons require fru(M) for proper pulse song execution and patterning of pulse structure, but not for pulse timing. This provides evidence that genes establishing sex-specific activation of complex behaviors may also be used in establishing pattern-generating motor networks underlying these sex-specific behaviors.

Prevalence of low bone mass in relation to estrogen treatment and body composition in male-to-female transsexual persons

Bone health is a parameter of interest in the daily follow-up of male-to-female (M --> F) transsexual persons both before and after sex reassignment surgery (SRS) due to an intensely changing hormonal milieu. We have studied body composition, areal, geometric, and volumetric bone parameters, using DXA and peripheral quantitative computed tomography at different sites in 50 M --> F transsexual persons, at least 3 yr after the start of the hormonal treatment and 1 yr after SRS. In this cross-sectional study, hormone levels and markers of bone metabolism were assessed using immunoassays. Prevalence of low bone mass as defined by a Z-score < or = -2.0 according to DXA criteria was 26% at lumbar spine and 2% at the total hip. We found no major differences in hormonal parameters between participants with a Z-score < or = or > -2.0. Markers of bone turnover were comparable between subjects with or without low bone mass, indicating a stable bone turnover at the time of investigation. No significant differences in bone size or density were observed between patients on transdermal vs. oral estrogens. Low bone mass is not uncommon in M --> F transsexual persons. Smaller bone size, and a strikingly lower muscle mass compared with men appear to underlie these findings.

Expression analysis of sex-specific and 17beta-estradiol-responsive genes in the Japanese medaka, Oryzias latipes, using oligonucleotide microarrays

Gene profiling of Japanese medaka (Oryzias latipes) was performed using an oligonucleotide DNA microarray representing 22,587 TIGR O. latipes gene indices (OLGIs). The average correlation coefficients for gene expression between individual mature fish were high (>0.95) for both female and male, indicating that the physiological status of medaka is highly reproducible under prescribed growth conditions. Of the 22,587 OLGIs, 2575 showed significant differences in expression between female and male. Exposure to 17beta-estradiol (E2) revealed 381 E2-responsive OLGIs in male medaka. Feminization and male-dysfunction factors of the E2-treated males calculated using the combination of Pearson correlation coefficient and Euclidean distances indicate that E2 treatment "weakly feminized" male medaka, while male physiological functions were not significantly disrupted. This study demonstrates the possibility of using medaka microarrays to estimate the overall effects of hormonally active chemicals.

Remote sensing of intraperitoneal parasitism by the host's brain: regional changes ofc-fosgene expression in the brain of feminized cysticercotic male mice

Experimental intraperitonealTaenia crassicepscysticercosis in mice exhibits distinct genetical, immunological and endocrinological features possibly resulting from the complex interactive network of their physiological systems. Very notable is the tendency of parasites to grow faster in hosts of the female sex. It is also remarkable in the feminization process that the infection induces in chronically infected male mice, characterized by their estrogenization, deandrogenization and loss of sexual and aggressive patterns of behaviour. The proto-oncogenec-fosis a sex steroid-regulated transcription factor gene, expressed basally and upon stimulation by many organisms. In the CNS of rodents,c-fosis found expressed in association to sexual stimulation and to various immunological and stressful events. Hence, we suspected that changes inc-fosexpression in the brain could be involved in the feminization of the infected male mice. Indeed, it was found thatc-fosexpression increased at different times during infection in the hypothalamus, hippocampus, less so in the preoptic area and cortex, and not in several other organs. The significant and distinctive regional changes ofc-fosin the CNS of infected mice indicate that the brain of the host senses intraperitoneal cysticercosis and may also announce its active participation in the regulation of the host–parasite relationship. Possibly, the host's CNS activity is involved in the network that regulates the estrogenization and deandrogenization observed in the chronically infected male mice, as well as in the behavioural and immunological peculiarities observed in this parasitic infection.

The presence of morphologically intermediate papilla syndrome in United Kingdom populations of sand goby (Pomatoschistus spp): endocrine disruption?

The sand goby (Pomatoschistus spp.) is a small estuarine fish. Its abundance, life history, and sedentary nature lead to its adoption as a key species in the U.K. Endocrine Disruption in the Marine Environment (EDMAR) Program. This study investigated the presence of classic markers of estrogenic exposure by determining vitellogenin (VTG) and zona radiata protein (ZRP) mRNA levels and ovotestis in estuarine-caught male gobies and investigated morphological changes in the urogenital papilla (UGP). Laboratory exposures to estrogens were also conducted to ascertain the responses of these markers. Wild-caught male fish showed no evidence of ovotestis, VTG, or ZRP mRNA induction. Laboratory exposures suggested that sensitivity of the goby to VTG/ ZRP mRNA induction was similar to flounder. The UGP inspection of wild-caught specimens revealed evidence of feminization of male papillae, a condition denoted as morphologically intermediate papilla syndrome (MIPS). Morphologically intermediate papilla syndrome was more prevalent at estrogenically contaminated sites. Juvenile goby experimentally exposed to 17beta-estradiol for 11 to 32 weeks exhibited signs of the MIPS condition, showing that it was inducible by estrogenic exposure and could therefore be a form of estrogenic endocrine disruption. The estuaries where the MIPS condition was most prevalent (>50% at certain sites) were the Tees, Mersey, and Clyde. The potential of the MIPS condition to significantly interfere with reproductive performance is discussed as well as its use as a monitoring tool for endocrine disruption in the estuarine environment.

Steroid deficiency syndromes in mice with targeted disruption of Cyp11a1

Steroid deficiencies are diseases affecting salt levels, sugar levels, and sexual differentiation. To study steroid deficiency in more detail, we used a gene-targeting technique to insert a neo gene into the first exon to disrupt Cyp11a1, the first gene in steroid biosynthetic pathways. Cyp11a1 null mice do not synthesize steroids. They die shortly after birth, but can be rescued by steroid injection. Due to the lack of feedback inhibition by glucocorticoid, their circulating ACTH levels are exceedingly high; this results in ectopic Cyp21 gene expression in the testis. Male Cyp11a1 null mice are feminized with female external genitalia and underdeveloped male accessory sex organs. Their testis, epididymis, and vas deferens are present, but undersized. In addition, their adrenals and gonads accumulate excessive amounts of lipid. The lack of steroid production, abnormal gene expression, and aberrant reproductive organ development resemble various steroid deficiency syndromes, making these mice good models for studies of steroid function and regulation.

Does androgen insufficiency cause lacrimal gland inflammation and aqueous tear deficiency?

PURPOSE

The current investigators have shown that androgen treatment suppresses inflammation and stimulates the function of lacrimal glands in mouse models of Sjögren's syndrome. Recently, others have hypothesized that androgen insufficiency induces an autoimmune process in lacrimal tissue, leading to inflammation, a Sjögren's syndrome-like pathology, and aqueous tear deficiency. The purpose of the present study was to test this hypothesis.

METHODS

Lacrimal glands were obtained from adult testicular feminized (Tfm) and control mice; castrated rats, guinea pigs, and rabbits; and castrated rats without anterior or whole pituitary glands and were processed for histology and image analysis. Tear volumes were measured in mice, in patients taking antiandrogen medications, and in age-matched human control subjects.

RESULTS

Tfm mice, which are completely resistant to classical androgen action, did not have increased lymphocyte infiltration in their lacrimal glands or decreased tear volumes. No inflammation was evident in lacrimal tissues of male or female rats, guinea pigs, or rabbits 12 to 31 days after castration, no inflammation existed in rat lacrimal glands 15 to 31 days after orchiectomy and pituitary removal, and no aqueous tear deficiency was apparent in patients receiving antiandrogen therapy.

CONCLUSIONS

Androgen deficiency may promote the progression of Sjögren's syndrome and its associated lacrimal gland inflammation, meibomian gland dysfunction, and severe dry eye. However, androgen insufficiency alone does not cause lacrimal gland inflammation, a Sjögren's syndrome-like pathology in lacrimal tissue, or aqueous tear deficiency in nonautoimmune animals and humans.

Feminization as a result of both peripheral conversion of androgens and direct estrogen production from an adrenocortical carcinoma

A 45-year-old man presented with gynecomastia, hypertension and a large left adrenal mass. Further evaluation revealed elevated serum concentrations of estrogen, estrone sulfate, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, deoxycorticosterone, and aldosterone and increased 24-hour urinary 17-ketosteroid and free cortisol excretion. Removal of a 10 kg adrenocortical carcinoma led to normalization of the hormone concentrations and partial resolution of the gynecomastia. There was no clinical evidence of metastases. Incubation of tumor slices demonstrated that the tumor had an active aromatase and sulfotransferase. We estimated that about half the serum estrone arose from peripheral conversion of androstenedione. Feminizing adrenocortical carcinomas are rare and this case is unusual given the lack of clinical metastases and the probable dual source of estrogen from tumor as well as from the peripheral conversion of tumor-derived androgens.

Murine Pax-2 protein is a sequence-specific trans-activator with expression in the genital system

The murine paired box containing gene Pax-2 has been proposed to be involved in kidney and central nervous system (CNS) development. In this report, we show that expression cloning of Pax-2 cDNA allowed in vitro identification of specifically bound DNA sequences. When fused to the thymidine kinase (TK) promoter in front of reporter genes, these target sequences were able to mediate trans-activation by Pax-2 protein, thus demonstrating their in vivo function. Expression studies from adult mouse tissues revealed high levels of Pax-2 transcripts in male and female genital tracts, suggesting a second phase of Pax-2 activity. Sequence-specific DNA binding and subsequent modulation of promoter activities may constitute the molecular mechanism of Pax-2 action in specific adult tissues and during development.

Effects of the gonadotrophin-releasing hormone agonist 'Zoladex' upon pituitary and gonadal function in hypogonadal (hpg) male mice: a comparison with normal male and testicular feminized (tfm) mice

Hypogonadal (hpg) mutant mice, with a congenital deficiency of hypothalamic gonadotrophin-releasing hormone (GnRH), and testicular feminized (tfm) mice, which lack a functional androgen receptor, were used to study the effects of the potent GnRH agonist 'Zoladex' (ICI 118630; D-Ser (Bu(t))6, Azgly10-GnRH) on pituitary and gonadal function. Zoladex (0.5 mg) in a sustained-release lactide-glycolide copolymer depot was administered subcutaneously under anaesthesia and was left in place for 7 days, after which time the effects of the drug upon pituitary and serum gonadotrophin concentrations, glycoprotein hormone subunit mRNAs and testicular morphology were investigated. At the pituitary level, Zoladex treatment resulted in a substantial reduction in LH content in normal males, and LH content was depressed in hpg mice even below the basal levels normally found in these mutants. Pituitary LH content in the Zoladex-treated animals was depressed in the tfm groups, but not to the same levels as those found in the normal and castrated normal mice. Zoladex treatment at the time of castration prevented the post-operative elevation in serum LH associated with castration alone. In the androgen-deficient tfm mouse, Zoladex did not depress the normally elevated serum LH levels. Serum LH in the hpg animals was, in all cases, below the limit of detection of the assay. Pituitary FSH content was depressed into the hpg range in both the normal and castrated animals, but there was no further depression in the hpg mice. The pituitary content was reduced in the tfm mice, again the effects not being as dramatic as in the normal and castrated animals. Serum FSH content, as measured by radioimmunoassay, was depressed by 50% in normal mice; there was no reduction in the hpg mice, however. With regard to pituitary gonadotrophic hormone gene expression, Zoladex administration to normal mice caused a dramatic reduction in LH beta mRNA content, to a level approximating that found in untreated hpg mice. The drug also depressed LH beta mRNA in the castrated group to the hpg range when given at the time of castration, whereas in untreated castrated mice there was a significant increase in LH beta mRNA. In the tfm mouse, which can be considered as a model for long-term failure of androgen feedback, Zoladex again induced a fall in LH beta mRNA, but not to the same extent as in the normal and normal castrated group. Zoladex had no effect on the already low levels of LH beta mRNA found in hpg mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Inability of Tfm (testicular feminization) epithelial cells to express androgen-dependent seminal vesicle secretory proteins in chimeric tissue recombinants

To assess the role of androgen receptors (ARs) in the expression of androgen-dependent seminal vesicle (SV) secretory proteins, tissue recombinants were prepared with rat seminal vesicle mesenchyme plus ureter epithelium of wild-type or Tfm mice (rat SVM plus wild-type mouse URE and rat SVM plus Tfm mouse URE, respectively). After growth in male hosts, both the wild-type and Tfm ureter epithelia were induced by SVM to differentiate into a simple columnar epithelium exhibiting the complex folded morphology characteristic of the SV. In SVM plus wild-type mouse URE recombinants, epithelial ARs were induced, and the epithelium expressed the full spectrum of SV secretory proteins. By contrast, in SVM plus Tfm mouse URE recombinants, the Tfm epithelium was genetically incapable of producing functional ARs and failed to produce SV secretory proteins. These data demonstrate in vivo that the induction of SV secretory proteins by androgens is an event requiring intraepithelial ARs. In contrast, androgen-dependent epithelial morphogenesis, columnar cytodifferentiation, and probably also proliferation can be expressed in Tfm epithelium grown in association with wild-type mesenchyme, strongly suggesting that these events are indirect effects on the epithelium mediated by mesenchymal ARs.

Aberrant splicing of androgen receptor mRNA results in synthesis of a nonfunctional receptor protein in a patient with androgen insensitivity

Androgen insensitivity is a disorder in which the correct androgen response in an androgen target cell is impaired. The clinical symptoms of this X chromosome-linked syndrome are presumed to be caused by mutations in the androgen receptor gene. We report a G----T mutation in the splice donor site of intron 4 of the androgen receptor gene of a 46,XY subject lacking detectable androgen binding to the receptor and with the complete form of androgen insensitivity. This point mutation completely abolishes normal RNA splicing at the exon 4/intron 4 boundary and results in the activation of a cryptic splice donor site in exon 4, which leads to the deletion of 123 nucleotides from the mRNA. Translation of the mutant mRNA results in an androgen receptor protein approximately 5 kDa smaller than the wild type. This mutated androgen receptor protein was unable to bind androgens and unable to activate transcription of an androgen-regulated reporter gene construct. This mutation in the human androgen receptor gene demonstrates the importance of an intact steroid-binding domain for proper androgen receptor functioning in vivo.

A single base mutation in the androgen receptor gene causes androgen insensitivity in the testicular feminized rat

The complete form of androgen insensitivity is an inherited X-linked syndrome in which genetic males fail to undergo masculinization in utero due to defective functioning of the androgen receptor (AR). The molecular basis of androgen insensitivity was investigated in the testicular feminized (Tfm) rat with this syndrome. AR mRNA size and amount, as well as nuclear AR protein revealed by immunocytochemistry, suggested normal expression of the AR gene in the Tfm rat. Sequence analysis of the AR coding region from Tfm and wild-type littermate male rats revealed a single transition mutation, guanine to adenine, within exon E, changing arginine 734 to glutamine within the steroid-binding domain of the AR. This arginine is highly conserved among the family of nuclear receptors and may be part of a phosphorylation recognition site. A recreated mutant AR (Arg734----Gln) expressed in COS cells had only 10-15% of the androgen-binding capacity of wild-type AR; the reduced androgen-binding capacity was similar to that of AR in tissue extracts of the Tfm rat. Stimulation of transcriptional activity by the recreated mutant AR was reduced relative to wild-type AR in cotransfection assays in CV1 cells using as reporter plasmid the mouse mammary tumor virus promoter linked to the chloramphenicol acetyltransferase gene. Thus, arginine 734 appears essential for normal AR function both in androgen binding and transcriptional activation. Absence of these functions results in androgen insensitivity and lack of male sexual development.

A single nucleotide substitution introduces a premature termination codon into the androgen receptor gene of a patient with receptor-negative androgen resistance

Mutations of the androgen receptor that impair the action of 5 alpha-dihydrotestosterone and testosterone result in abnormal male sexual development. The definition of the organization of the androgen receptor gene has permitted us to examine its structure in nine patients with androgen resistance that exhibit absent 5 alpha-dihydrotestosterone binding in cultured fibroblasts (receptor-negative androgen resistance). Using labeled probes specific for each individual coding exon, we find no gross rearrangements, insertions, or deletions of the androgen receptor gene in these patients. To analyze the genetic defect in these receptor-negative patients, we used the polymerase chain reaction to amplify each individual exon of the androgen receptor gene in nine affected patients. In all patients, the size of each amplified exon segment was identical to that in normal individuals. The nucleotide sequence of the entire coding region of the androgen receptor was determined in one of these patients. A single nucleotide substitution was identified that results in a premature termination codon in exon 6 at amino acid 794. S1 nuclease protection assays demonstrated that normal levels of androgen receptor mRNA are present in skin fibroblasts of this patient. Transfection of a mutated androgen receptor cDNA containing a termination codon at position 794 into eukaryotic cells resulted in formation of a normal amount of receptor protein, as indicated by immunoblotting, but the expressed protein does not bind 5 alpha-dihydrotestosterone. These findings suggest that the presence of a premature termination codon at amino acid 794 of the androgen receptor is the cause of androgen resistance in this patient.

Estrogenic feminization of the LH response to orchidectomy: association with prolonged nuclear estradiol receptor retention and induction of cytoplasmic progestin receptors in brain and pituitary

A sex difference in the LH rise after gonadectomy is clearly observable in the rat. While male rats respond with an early (10-12 h) increase in LH after orchidectomy, a delayed response (2-3 days) is recorded after ovariectomy. In this study we tested the hypothesis that the delayed response to gonadectomy in the E2-treated males is due to a more prolonged retention of E2 (when compared with the corresponding male feedback signal, testosterone) within specific central nuclear receptor sites. Orchidectomized (ORDX) animals implanted with either empty or E2-filled Silastic capsules were sacrificed at 0, 24, 48 and 72 h after ORDX or E2-capsule removal. LH levels in ORDX rats rose several-fold by 24 h, whereas E2-treated, ORDX rats, showed no changes in peripheral LH levels until 72 h after E2-capsule removal. At the time of E2-capsule removal (0 h) large increases in nuclear estradiol receptor (NER) levels were seen in anterior pituitary, preoptic area, and hypothalamus (HYP). Twenty-four hours after E2-capsule removal, NER levels were still high in the 3 areas, and by 48 h NER values had returned to control (ORDX) levels, with the exception of HYP where they were slightly but significantly elevated. The increase in NER, as well as the subsequent decline after E2-capsule removal was paralleled by similar changes in cytosolic progestin receptor (CPR) levels in all three regions. Cytosolic testosterone levels were not changed by the E2-treatment. The results indicate that the feminized response to orchidectomy observed in E2-implanted males is related to a prolonged retention of the E2-receptor in nuclear sites. Further, they indicate that E2-treatment in males, as is the case in females, can induce a marked increase in progestin receptor levels within specific brain regions as well as in the pituitary. The reduction in NER and CPR levels to castrate values precedes the first detectable increase in peripheral LH levels. In conclusion, the pattern of LH rise after gonadectomy in the rat is dependent upon the steroidal milieu at the time of removal of the gonads.

Effects of hypothalamic deafferentation at different levels on metabolism of hepatic steroids in rats

The metabolism of 4-[4-14C]androstene-3,17-dione in the microsomal fraction of livers from male and female rats was investigated after hypothalamic deafferentation at two levels. It was found that frontal deafferentation at the retrochiasmatic level caused a complete 'feminization' of hepatic steroid metabolism in the male rat but was without effect in the female animal. Transection rostral to the suprachiasmatic nuclei was without effect in both sexes. A complete transition from male to female hepatic steroid metabolism after retrochiasmatic deafferentation was reached on day 4 after the operation and persisted for at least 10 weeks. The present results, taken together with previous investigations, indicate that the release of a 'feminizing' factor from the pituitary gland of the male rat is inhibited by a factor produced in, or transported through, the periventricular anterior hypothalamic region including the suprachiasmatic area. No effect on the hepatic steroid metabolism was observed after binding of the rats suggesting that a diurnal rhythm is not essential to this control mechanism.

Progestin binding in testes from three siblings with the syndrome of male pseudohermaphroditism with testicular feminization

We have found a specific binding protein for synthetic progestins 6,7-[3H]methyltrienolone (R1881) and 17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione (R5020) and in the testis cytosol from three "sisters" with the complete form of the testicular feminization syndrome. The binding component sediments in the 8S region of sucrose gradients. It is saturable. The apparent affinity constant (Ka) for R5020 was determined in two cases and found to be 1.8 and 0.6 X 10(8) M-1. The number of binding sites calculated from Scatchard plots is relatively high: 572 and 826 fmol/mg protein. Competition studies indicate that this putative receptor is specific for natural and synthetic progestins but not for 5 alpha-dihydrotestosterone and cortisol. Similar progestin binding could not be found in normal human and rat testes.

Precocious 'feminization' of rat liver enzymes in the presence of ectopic pituitary tissue

The presence of ectopic pituitary tissue (derived from an adult rat) in prepubertal male and female rats caused the immature, masculine-type hepatic steroid metabolism to develop into female-type metabolism. It is concluded that the hypothalamus-pituitary system controls the ontogenesis of sex-dependent steroid metabolism in rat liver.

Feminization of hepatic steroid metabolism in male rats following electrothermic lesion of the hypothalamus

The metabolism of [4-14C]androst-4-ene-3,17-dione, [4-14C]5alpha-androstane-3alpha,17beta-diol and [1,2-3H]5alpha-androstane-3alpha,17beta-diol, 3,17-disulfate in the 105,000 X g supernatant and microsomal fractions of liver was studied in male and female rats after electrothermic lesion of the hypothalamus including the median eminence. Following electrothermic lesion, hepatic steroid metabolism in male rats was generally "feminized" (increased 5alpha-reduction and decreased 6beta- and 16alpha-hydroxylation of 4-androstene-3,17-dione, decreased 2alpha-, 2beta-, 18- and 7beta-hydroxylation of 5alpha-androstane-3alpha, 17beta-diol and induced 15beta-hydroxylation of 5alpha-androstane-3alpha,17beta-diol,3,17-disulfate), whereas hepatic metabolism in female rats remained essentially unchanged. Previous investigations have pointed to the occurrence of a sex-specific secretion of "feminizing factor" from the female pituitary that is responsible for the "feminization" of the basically "masculine" type of metabolism characterizing the rat liver. Taken together with these findings, the present results indicate that the release of the pituitary "feminizing factor" is controlled by means of a release-inhibiting factor from the hypothalamus. This factor is not secreted in female rats; it is suggested that its secretion in male rats is turned on as a result of neonatal imprinting by testicular androgens.

Sexual differentiation in the phase of the circadian rhythm of (35S) methionine incorporation into cerebral proteins, and of serum gonadotrophin levels

The incorporation of [35S]methionine into protein in various regions of the brain and in the anterior pituitary, and serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured at 6 h intervals throughout a 24 h period in the following groups of Wistar rats: (1) normal adult males and females; (2) adult genetic males or females which had been respectively 'feminized' or 'masculinized' by androgen deprivation or administration in neonatal life. Similar measurements were made at 12 h intervals in adult male rats which had been castrated at 7 or 15 days of age.

Serum LH levels showed a circadian rhythmicity in normal adult animals of both sexes, with peak levels in the male occurring 6 h earlier than those in the female. There was no statistically significant circadian rhythm in FSH levels in any group of animals. In all groups of castrated animals LH and FSH levels were raised but no circadian rhythms were observed.

Incorporation of [35S]methionine into protein in all cerebral areas showed circadian rhythms, the peak values of which, in the adult males, were almost 8 h (120°) out of phase with those of the adult females. In the 'feminized' genetic males or 'masculinized' genetic females the rhythmic phase was reversed to that of the opposite genetic sex. Animals castrated at 7 days or 15 days of age did not appear to show a rhythm.

A 12 h rhythm of incorporation was apparent in the anterior pituitary of the normal adult male and the adult 'masculinized' female; no significant rhythm was seen in the normal adult female and the 'feminized' male.

It is suggested that a 'female type' rhythm of incorporation in the brain may be associated with the maintenance of oestrous cycles.

Sex- and age-dependent hydroxylations of testosterone in the liver of normally developed rats and in animals with disturbed sexual development

The formation rate of C19O3 (C19O4)-metabolites from testosterone incubated with rat liver microsomes is subject to an age-dependent development and sex-specific differentiation. An investigation of the formation of individual testosterone hydroxylation products demonstrates an age dependence in all cases. This age dependence may display sex differences (as in the production of 6β- and 16α-hydroxytestosterone), or be independent of sex (as in the production of 7α-hydroxytestosterone). At maturity, male animals produce significantly more 6β-hydroxytestosterone than females; 16α-hydroxytestosterone is a sex-specific metabolite found only in male animals.

The administration of oestradiol benzoate (300 μg on day 2 of life) leads to feminization in the mature male animal, as demonstrated by the decrease of 6β-hydroxytestosterone formation to a typically female level, and by the cessation of 16α-hydroxytestosterone production. 7α-Hydroxytestosterone formation, which is not sex-dependent, is not affected by this oestrogenization.