Changes In Androgen Receptor Expression Research Articles

Dynamic plasticity of prostate cancer intermediate cells during androgen receptor-targeted therapy.

Treatment-emergent small cell neuroendocrine prostate cancer (t-SCNC) is associated with an epithelial lineage switch from an androgen receptor (AR)-positive to neuroendocrine (NE)-marker-positive status. Understanding the potential for reversibility of this aggressive disease state has been hampered by the paucity of models suitable for studying rate-limiting, transitional, or intermediate tumor cell subpopulations. We define a dual reporter model that measures acute transcriptional changes in response to castration or AR targeting agents. We identify steady-state transcriptional heterogeneity in AR and NE biomarkers, including intermediate subpopulations that are coordinately high for prostate-specific antigen (PSA) and neuron-specific enoclase (NSE) promoter activity. In the presence of castration or AR inhibitors, intermediate cells were necessary and sufficient for therapy-induced conversion of human PC cells to an NSE-high transcriptional status. Using hormone add-back studies, treatment-induced PSA-NSE transcriptional plasticity was reversible in PTEN-deficient PC cells but not in the presence of secondary genetic driver genes, including MYCN.

Changes in Androgen Receptor Expression as a Molecular Marker of Progression from Normal Epithelium to Invasive Cancer in Elderly Patients with Penile Squamous Cell Carcinoma.

Changes in Androgen Receptor Expression as a Molecular Marker of Progression from Normal Epithelium to Invasive Cancer in Elderly Patients with Penile Squamous Cell Carcinoma.

Age- and Sex-Dependent Changes in Androgen Receptor Expression in the Developing Mouse Cortex and Hippocampus.

During the perinatal period, male mice are exposed to higher levels of testosterone (T) than females, which promotes sexual dimorphism in their brain structures and behaviors. In addition to acting via estrogen receptors after being locally converted into estradiol by aromatase, T also acts directly through androgen receptor (AR) in the brain. Therefore, we hypothesized that AR expression in the developing mouse cortex and hippocampus was sexually dimorphic. To test our hypothesis, we measured and determined AR mRNA and protein levels in mouse cortex/hippocampus collected on the day of birth (PN0) and 7 (PN7), 14 (PN14), and 21 (PN21) days after birth. We demonstrated that, as age advanced, AR mRNA levels increased in the cortex/hippocampus of both sexes but showed no sex difference. Two AR proteins, the full-length (110 kDa) and a smaller isoform (70 kDa), were detected in the developing mouse cortex/hippocampus with an age-dependent increase in protein levels of both AR isoforms at PN21 and a transient masculine increase in expression of the full-length AR protein on PN7. Thus, we conclude that the postnatal age and sex differences in AR protein expression in combination with the sex differences in circulating T may cause sexual differentiation of the mouse cortex/hippocampus.

Increased expression of the androgen receptor with p300 and interleukin-6 coactivators compensate for oligonucleotide suppression of bcl-2: no increased CREB binding protein or interleukin-4 expression

Antisense oligonucleotides (oligos) have been employed against in vivo and in vitro prostate cancer models targeting growth regulatory proteins. While most oligos have targeted growth factors or their receptors, others have been directed against inhibitors of apoptosis and mediators of androgen action. We previously evaluated a set of oligos which targeted and comparably suppressed the expression of the apoptosis inhibitor protein bcl-2. LNCaP cells adapted to this restoration of apoptosis with suppression of caspase 3 (an apoptosis promoter) and an enhanced expression of the androgen receptor (AR), suggesting an increased sensitivity to androgens. In a continuation of this study, we evaluated the expression of AR coactivators p300, its homolog CREB binding protein (CREBBP) and cytokines interleukin (IL)-4 and IL-6, finding p300 and IL-6 similarly enhanced. LNCaP cells are hormone sensitive and untreated cells express minimal p300 activity. Therefore, the enhanced expression which followed oligo treatment makes its induction more impressive and implies a pattern of gene expression more associated with later stage (androgen insensitive) disease. This suggests that oligo treatment directed against bcl-2 can be evaded through compensatory changes in AR expression and some coactivators, promoting tumor growth, and may promote transformation of the tumor to a more aggressive phenotype.

Transient Gestational and Neonatal Hypothyroidism-induced Specific Changes in Androgen Receptor Expression in Skeletal and Cardiac Muscles of Adult Rat

The present study aims to identify the association between androgen status and metabolic activity in skeletal and cardiac muscles of adult rats with transient gestational/neonatal-onset hypothyroidism. Pregnant and lactating rats were made hypothyroid by exposing to 0.05% methimazole in drinking water; gestational exposure was from embryonic day 9-14 (group II) or 21 (group III), lactational exposure was from postnatal day 1-14 (group IV) or 29 (group V). Serum was collected for hormone assay. Androgen receptor status, Glu-4 expression, and enzyme activities were assessed in the skeletal and cardiac muscles. Serum testosterone and estradiol levels decreased in adult rats of groups II and III, whereas testosterone remained normal but estradiol increased in group IV and V, when compared to coeval control. Androgen receptor ligand binding activity increased in both muscle phenotypes with a consistent increase in the expression level of its mRNA and protein expressions except in the forelimb of adult rats with transient hypothyroidism (group II-V). Glut-4 expression remained normal in skeletal and cardiac muscle of experimental rats. Specific activity of hexokinase and lactate dehydrogenase increased in both muscle phenotypes whereas, creatine kinase activity increased in skeletal muscles alone. It is concluded that transient gestational/lactational exposure to methimazole results in hypothyroidism during prepuberal life whereas it increases AR status and glycolytic activity in skeletal and cardiac muscles even at adulthood. Thus, the present study suggests that euthyroid status during prenatal and early postnatal life is essential to have optimal AR status and metabolic activity at adulthood.

Differential effects of androgens on coronary blood flow regulation and arteriolar diameter in intact and castrated swine

BackgroundLow endogenous testosterone levels have been shown to be a risk factor for the development of cardiovascular disease and cardiovascular benefits associated with testosterone replacement therapy are being advocated; however, the effects of endogenous testosterone levels on acute coronary vasomotor responses to androgen administration are not clear. The objective of this study was to compare the effects of acute androgen administration on in vivo coronary conductance and in vitro coronary microvascular diameter in intact and castrated male swine.MethodsPigs received intracoronary infusions of physiologic levels (1–100 nM) of testosterone, the metabolite 5α-dihydrotestosterone, and the epimer epitestosterone while left anterior descending coronary blood flow and mean arterial pressure were continuously monitored. Following sacrifice, coronary arterioles were isolated, cannulated, and exposed to physiologic concentrations (1–100 nM) of testosterone, 5α-dihydrotestosterone, and epitestosterone. To evaluate effects of the androgen receptor on acute androgen dilation responses, real-time PCR and immunohistochemistry for androgen receptor were performed on conduit and resistance coronary vessels.ResultsIn vivo, testosterone and 5α-dihydrotestosterone produced greater increases in coronary conductance in the intact compared to the castrated males. In vitro, percent maximal dilation of microvessels was similar between intact and castrated males for testosterone and 5α-dihydrotestosterone. In both studies epitestosterone produced significant increases in conductance and microvessel diameter from baseline in the intact males. Androgen receptor mRNA expression and immunohistochemical staining were similar in intact and castrated males.ConclusionsAcute coronary vascular responses to exogenous androgen administration are increased by endogenous testosterone, an effect unrelated to changes in androgen receptor expression.

In LNCaP cells enhanced expression of both androgen receptor and costimulatory protein p300 compensate for antisense oligonucleotide suppression of bcl-2.

Antisense oligonucleotides (oligos) have been employed against in vivo and in vitro prostate cancer models targeting growth stimulatory gene products. While most oligos have targeted growth factors or their receptors, others have been directed against inhibitors of apoptosis and mediators of androgen action. In LNCaP cells we evaluated a set of oligos which targeted and comparably suppressed the expression of the apoptosis inhibitor protein bcl-2. LNCaP cells adapted to this restoration of apoptosis with an enhanced expression of the androgen receptor (AR) suggesting an increased sensitivity to androgens. In a continuation of this study, we now evaluate the expression of p300, an AR coactivating protein expressed in the later stages of prostate cancer. In previous experiments, monospecific and bispecific oligos directed against bcl-2 suppressed both the targeted bcl-2 protein (an inhibitor of apoptosis) and the nontargeted caspase-3 (a promoter of apoptosis), potentially negating the effect on apoptosis produced by specific inhibition of bcl-2. In a further study we reported that expression of the AR was significantly enhanced by these oligos. We now report that expression of p300 is similarly enhanced. LNCaP cells are hormone sensitive and the untreated cells expressed minimal p300 activity. The enhanced expression which followed oligo treatment makes its induction more impressive, and implies a pattern of gene expression more associated with later stage (androgen-insensitive) disease. This suggests that oligo treatment directed against bcl-2 not only can be evaded through compensatory changes in AR expression which promotes tumor growth, but the induced expression of p300 may transition the tumor to a more dedifferentiated and aggressive phenotype.

Expression of androgen receptor and estrogen receptor-alpha in the developing pituitary gland of male sheep lamb

To explore the expression of androgen receptor (AR) and estrogen receptor alpha (ERα) in the developing pituitary of male lamb, we detected AR and ERα expression in the anterior pituitary of lambs aged 2–7 months old by immunohistochemistry. The results showed that both AR immunoreactivity (AR-ir) and ERα immunoreactivity (ERα-ir) were localized in the nuclei of anterior pituitary cell. The percentage of the anterior pituitary cells expressing ERα fluctuated from 8.79 ± 0.02% to 11.80 ± 0.04% during the examined stages, but fell significantly to the lowest level at 6 months. While the proportion of AR-ir showed significant changes, it was in 11.52 ± 1.26% at 2 months, it firstly increased to 19.86 ± 1.03% at 3 months, and then significantly decreased to 8.18 ± 1.17% at 6 months ( P < 0.05). The expression of both AR-ir and ERα-ir were the lowest level at 6 months old. By staining for PCNA, we observed that the changes in expression of AR and ERα at different lamb ages did not result from cell proliferation of anterior pituitary cells. These results indicate that both AR and ERα are important in regulation of secretary function of anterior pituitary in sheep lamb, although the related mechanism needs to be elucidated further.

SENP1 Induces Prostatic Intraepithelial Neoplasia through Multiple Mechanisms

SUMOylation has been shown to modulate DNA replication/repair, cell cycle progression, signal transduction, and the hypoxic response. SUMO (small ubiquitin-like modifier)-specific proteases regulate SUMOylation, but how changes in the expression of these proteases contribute to physiological and/or pathophysiological events remains undefined. Here, we show that SENP1 (sentrin/SUMO-specific protease 1) is highly expressed in human prostate cancer specimens and correlates with hypoxia-inducing factor 1alpha (HIF1alpha) expression. Mechanistic studies in a mouse model indicate that androgen-driven expression of murine SENP1 leads to HIF1alpha stabilization, enhanced vascular endothelial growth factor production, and angiogenesis. Further pathological assessment of the mouse indicates that SENP1 overexpression induces transformation of the normal prostate gland and gradually facilitates the onset of high-grade prostatic intraepithelial neoplasia. Consistent with cell culture studies, SENP1 enhances prostate epithelial cell proliferation via modulating the androgen receptor and cyclin D(1). These results demonstrate that deSUMOylation plays a critical role in prostate pathogenesis through induction of HIF1alpha-dependent angiogenesis and enhanced cell proliferation.

Mullerian Inhibiting Substance Regulates Androgen-Induced Gene Expression and Growth in Prostate Cancer Cells through a Nuclear Factor-κB-Dependent Smad-Independent Mechanism

Mullerian inhibiting substance (MIS), a member of the TGFbeta superfamily, causes regression of the Mullerian duct in male embryos. The presence of MIS type II and type I receptors in tissues and cell lines derived from the prostate suggests that prostate is a likely target for MIS. In this report, we demonstrate that MIS inhibits androgen-stimulated growth of LNCaP cells and decreases their survival in androgen-deprived medium by preventing cell cycle progression and inducing apoptosis. Expression of dominant-negative Smad1 reversed the ability of MIS to decrease LNCaP cell survival in androgen-deprived medium but not androgen-stimulated growth, whereas abrogation of nuclear factor-kappaB (NFkappaB) activation ablated the suppressive effects of MIS on both androgen-stimulated growth and androgen-independent survival. The effect of MIS on androgen-induced growth was not due to changes in androgen receptor expression. However, MIS suppressed androgen-stimulated transcription of prostate-specific antigen; ablation of NFkappaB activation reversed MIS-mediated suppression of prostate-specific antigen. These observations suggest that MIS regulates androgen-induced gene expression and growth in prostate cancer cells through a NFkappaB-dependent but Smad1-independent mechanism. Thus, MIS, in addition to potentially regulating prostate growth indirectly by suppressing testicular testosterone synthesis, may also be a direct regulator of androgen-induced gene expression and growth in the prostate at the cellular level.

Loss of Bmp7 and Fgf8 signaling in Hoxa13-mutant mice causes hypospadia.

In humans and mice, mutations in Hoxa13 cause malformation of limb and genitourinary (GU) regions. In males, one of the most common GU malformations associated with loss of Hoxa13 function is hypospadia, a condition defined by the poor growth and closure of the urethra and glans penis. By examining early signaling in the developing mouse genital tubercle, we show that Hoxa13 is essential for normal expression of Fgf8 and Bmp7 in the urethral plate epithelium. In Hoxa13(GFP)-mutant mice, hypospadias occur as a result of the combined loss of Fgf8 and Bmp7 expression in the urethral plate epithelium, as well as the ectopic expression of noggin (Nog) in the flanking mesenchyme. In vitro supplementation with Fgf8 restored proliferation in homozygous mutants to wild-type levels, suggesting that Fgf8 is sufficient to direct early proliferation of the developing genital tubercle. However, the closure defects of the distal urethra and glans can be attributed to a loss of apoptosis in the urethra, which is consistent with reduced Bmp7 expression in this region. Mice mutant for Hoxa13 also exhibit changes in androgen receptor expression, providing a developmental link between Hoxa13-associated hypospadias and those produced by antagonists to androgen signaling. Finally, a novel role for Hoxa13 in the vascularization of the glans penis is also identified.

Immunohistochemical detection of androgen receptors in the canine uterus throughout the estrus cycle

Serum androgen levels in the bitch increase during proestrus and remain elevated until metestrus. To find out whether androgens can have a direct impact on the canine uterus, androgen receptors (AR) were identified immunohistochemically in uterine tissue. Androgen receptor distribution in the uterine horns, body and cervix was described during different cycle stages, during pregnancy and in the postpartum period. Nuclear staining for AR was observed in cells of the surface epithelium, glandular ducts, basal glands and stroma of the endometrium, and in myometrial smooth muscle cells. In addition, cytoplasmic staining was observed in epithelial cells from proestrus to early metestrus, when the cells were secretory active, and in stroma cells during pregnancy, suggesting a role for androgens in decidualization. During pregnancy and in the postpartum period nuclear staining for AR was nearly absent. During the estrus cycle stroma cells stained with higher intensities for AR than epithelial cells, supporting the idea that stroma cells mediate some effects of steroid hormones on epithelial cells in the genital tract. In contrast with earlier findings on estrogen receptor-α and progesterone receptors, no significant changes in androgen receptor expression were observed during the estrus cycle. Few correlations were found between the staining for AR and serum levels of the sex steroids. The present findings suggest that there is a basal expression of AR in the canine uterus throughout the estrus cycle that may not be influenced by sex steroid hormones.

Suppression of androgen action and the induction of gross abnormalities of the reproductive tract in male rats treated neonatally with diethylstilbestrol.

This study evaluated whether androgen action is altered in rats treated neonatally with diethylstilbestrol (DES) at a dose that induced reproductive tract abnormalities. Rats were treated on alternate days 2-12 with 10 microg DES and studied on Day 18. DES-induced abnormalities included a 70% reduction in testis weight, distension and overgrowth of the rete, distension and reduction in epithelial height of the efferent ducts, underdevelopment of the epididymal duct epithelium, reduction in epithelial height in the vas deferens, and convolution of the extra-epididymal vas. In DES-treated rats, androgen receptor (AR) immunoexpression was virtually absent from all affected tissues and the testis, whereas AR expression in controls was intense in epithelial and stromal cells. The DES-induced change in AR immunoexpression was confirmed by Western analysis for the testis. In rats treated neonatally with 1 microg DES, reproductive abnormalities were absent or minor, except for a 38% reduction in testis weight; loss of AR immunoexpression also did not occur in these rats. Treatment-induced changes in AR expression were paralleled by changes in Leydig cell volume per testis (91% reduction in the 10-microg DES group; no change in the 1-microg DES group). To test whether suppression of androgen production or action alone could induce comparable reproductive abnormalities to 10 microg DES, rats were treated neonatally with either a potent gonadotropin-releasing hormone antagonist (GnRHa) or with flutamide (50 mg/kg/day). These treatments reduced testis weight (68% for GnRHa, 40% for flutamide), and generally retarded development of the reproductive tract but failed to induce the abnormalities induced by 10 microg DES. GnRHa and flutamide caused no detectable change in AR immunoexpression in target tissues, with the exception of minor changes in the testes of flutamide-treated males. GnRHa treatment caused a reduction (83%) in Leydig cell volume comparable to that caused by 10 microg DES. Immunoexpression of estrogen receptor alpha (ER alpha) in the efferent ducts and of ER beta in all tissues studied were unaffected by any of the above treatments. Neonatal coadministration of testosterone esters (TE; 200 microg) with 10 microg DES prevented most of the morphological abnormalities induced by 10 microg DES treatment alone, though testis weight was still subnormal (46% reduction in DES + TE vs 72% in DES alone and 49% with TE alone) and some lumenal distension was still evident in the efferent ducts. Coadministration of TE with DES prevented DES-induced loss of AR immunoexpression (confirmed for testis by Western blot analysis). It is concluded that 1) reproductive tract abnormalities induced in the neonatal male rat by a high (10 microg) dose of DES are associated with reduced AR expression and Leydig cell volume; 2) these changes are largely absent with a lower dose of DES (1 microg); 3) treatments that interfere with androgen production (GnRHa) or action (flutamide) alone failed to induce reproductive tract abnormalities or alter AR expression as did 10 microg DES; 4) a grossly altered androgen:estrogen balance (low androgen + high estrogen) may underlie the reproductive tract abnormalities, other than reduced testis weight, induced by high doses of DES.

Photoperiod-induced changes in androgen receptor expression in testes and accessory sex glands of the bank vole, Clethrionomys glareolus.

Photoperiodic modulation of androgen levels and androgen receptor (AR) expression in testes and accessory sex glands were studied in a seasonally breeding rodent, the bank vole. Juvenile voles subjected to long photoperiod (20L:4D) for 6-8 wk attained sexual maturity, which was associated with a prominent increase in testicular testosterone (T) levels and weight of testes and accessory sex glands. Pubertal development in short photoperiod-treated (6L:18D for 6-8 wk) juveniles was arrested, and subsequently reproductive regression set in with a marked decrease in testicular T levels and gonadal weight. In sexually active voles, strong AR immunostaining was detected in nuclei of epithelial, smooth muscle, and stromal cells of the epididymis, prostate, and seminal vesicles. In active testes, AR was present in nuclei of Sertoli cells, peritubular cells, Leydig cells, and vascular smooth muscle cells. In juveniles, strong to moderate nuclear immunoreactivity was encountered in epithelial and stromal cells of the epididymis and prostate, whereas a weaker reaction was discerned in seminal vesicles. In juvenile testes, AR was localized to vascular smooth muscle cells, peritubular, and interstitial cells. In sexually regressed animals, nuclear staining was almost absent in accessory sex glands, whereas in testes, moderate immunostaining was retained in all other cell types except the Sertoli cells. Western blots of active and regressed testes indicated a marked photoperiod-induced down-regulation of immunodetectable AR in the regressed gonad.

Immunocytochemical detection of androgen receptor in human temporal cortex: Characterization and application of polyclonal androgen receptor antibodies in frozen and paraffin-embedded tissues

Immunocytochemical and biochemical studies have demonstrated the presence of androgen receptor protein in various regions of the rodent and non-human primate cortex. Localization of androgen receptor in the human brain has, however, not been studied as extensively, because of difficulties in obtaining suitable tissue samples. In the present study, we have localized androgen receptors in both frozen and paraffin-embedded temporal cortex from epileptic patients undergoing resection. Polyclonal antibodies were raised against fusion proteins containing fragments of the human androgen receptor protein. The antibodies were affinity-purified against the corresponding fusion protein. Immunoprecipitation and Western blotting using extracts from human cell lines demonstrated the specificity of the antibodies for the human androgen receptor and lack of cross-reactivity with other steroid hormone receptors. Immunocytochemistry was performed on frozen and paraffin sections of human temporal cortex and in paraffin-embedded benign hyperplastic prostates (BPH), as well as prostate and breast carcinomas, by the streptavidin-biotin-peroxidase method. Antigenretrieval was performed in paraffin-embedded sections using microwave irradiation. Specific nuclear and cytoplasmic immunoreactivity for androgen receptor was detected in neurons, astrocytes, oligodendrocytes, and microglia cells of the temporal cortex. In contrast, only nuclear staining was observed in BPH, prostate and breast carcinomas. Immunoprecipitation of human temporal cortex lysate and subsequent Western blot analysis demonstrated the expression of a 98 kDa immunoreactive protein, slightly smaller than the reported molecular weight of the wild-type androgen receptor. These results provide further evidence for the expression of androgen receptor in the human temporal cortex. The use of these immunocytochemical techniques should enable the retrospective determination of possible changes in androgen receptor expression in a variety of archival paraffin-embedded tissues, including samples of the human central nervous system.

Neonatal estrogen exposure induces lobe-specific alterations in adult rat prostate androgen receptor expression.

Brief administration of estrogen to newborn rats results in permanent suppression of prostate growth and reduced prostatic responsiveness to testosterone in adulthood. To determine whether this imprinting may be a result of alterations in androgen receptor (AR) expression, the separate adult prostate lobes of neonatally estrogenized rats were examined for AR concentration and distribution. Sprague-Dawley rat pups were given 25 micrograms estradiol benzoate or oil alone on days 1, 3, and 5 and were killed on day 90. Half of the animals received 2-cm testosterone implants 10 days before death to assess the activational response to androgen. In a separate series, neonatally estrogenized rats were given prepubertal dihydrotestosterone pellets for 3 weeks as well as testosterone implants in adulthood to determine if the observed effects of neonatal estrogen on the adult prostate were an indirect result of androgen deprivation during developmentally critical periods. The ventral, dorsal, and lateral prostate lobes were processed for nuclear AR quantitation by [3H]dihydrotestosterone exchange binding assay and for indirect immunocytochemical localization of AR. Weights and DNA contents of the three prostate lobes were significantly reduced in neonatally estrogenized rats, and this decrease was only partially reversed by prepubertal and/or adult androgen replacement. Histologically, the hypoplastic ventral and dorsal lobes exhibited a relative increase in interacinar stromal tissue, disorganized acini with epithelial hyperplasia, luminal sloughing, and an apparent lack of differentiation. The hypoplastic lateral lobe also showed a relative increase in the stromal fraction; however, the acinar epithelium appeared differentiated, with normal basal/apical orientation and luminal secretions. The AR concentration was significantly reduced in the ventral and dorsal prostates of estrogenized rats, but was unaltered in the lateral lobe. Immunocytochemistry revealed a marked reduction or absence of epithelial AR in ventral and dorsal lobes from estrogenized rats, whereas the lateral lobe epithelial cells expressed AR similarly to controls. The incidence of AR-positive fibroblastic stromal cells increased in lateral prostates from 5% in controls to approximately 25% in estrogenized rats. Neonatally estrogenized rats given testosterone for 10 days in adulthood showed increased levels of AR in the ventral and dorsal lobes compared to nonstimulated rats; however, these levels remained well below control values. Lateral lobe epithelial histology and AR expression appeared relatively unchanged in estrogenized rats given testosterone during adulthood, whereas an increased proportion of stromal cells (approximately 35%) were AR positive. In summary, neonatal estrogen administration permanently altered prostatic growth and produced lobe-specific changes in AR expression in the adult gland.(ABSTRACT TRUNCATED AT 400 WORDS)

Neonatal estrogen exposure induces lobe-specific alterations in adult rat prostate androgen receptor expression.

Brief administration of estrogen to newborn rats results in permanent suppression of prostate growth and reduced prostatic responsiveness to testosterone in adulthood. To determine whether this imprinting may be a result of alterations in androgen receptor (AR) expression, the separate adult prostate lobes of neonatally estrogenized rats were examined for AR concentration and distribution. Sprague-Dawley rat pups were given 25 micrograms estradiol benzoate or oil alone on days 1, 3, and 5 and were killed on day 90. Half of the animals received 2-cm testosterone implants 10 days before death to assess the activational response to androgen. In a separate series, neonatally estrogenized rats were given prepubertal dihydrotestosterone pellets for 3 weeks as well as testosterone implants in adulthood to determine if the observed effects of neonatal estrogen on the adult prostate were an indirect result of androgen deprivation during developmentally critical periods. The ventral, dorsal, and lateral prostate lobes were processed for nuclear AR quantitation by [3H]dihydrotestosterone exchange binding assay and for indirect immunocytochemical localization of AR. Weights and DNA contents of the three prostate lobes were significantly reduced in neonatally estrogenized rats, and this decrease was only partially reversed by prepubertal and/or adult androgen replacement. Histologically, the hypoplastic ventral and dorsal lobes exhibited a relative increase in interacinar stromal tissue, disorganized acini with epithelial hyperplasia, luminal sloughing, and an apparent lack of differentiation. The hypoplastic lateral lobe also showed a relative increase in the stromal fraction; however, the acinar epithelium appeared differentiated, with normal basal/apical orientation and luminal secretions. The AR concentration was significantly reduced in the ventral and dorsal prostates of estrogenized rats, but was unaltered in the lateral lobe. Immunocytochemistry revealed a marked reduction or absence of epithelial AR in ventral and dorsal lobes from estrogenized rats, whereas the lateral lobe epithelial cells expressed AR similarly to controls. The incidence of AR-positive fibroblastic stromal cells increased in lateral prostates from 5% in controls to approximately 25% in estrogenized rats. Neonatally estrogenized rats given testosterone for 10 days in adulthood showed increased levels of AR in the ventral and dorsal lobes compared to nonstimulated rats; however, these levels remained well below control values. Lateral lobe epithelial histology and AR expression appeared relatively unchanged in estrogenized rats given testosterone during adulthood, whereas an increased proportion of stromal cells (approximately 35%) were AR positive. In summary, neonatal estrogen administration permanently altered prostatic growth and produced lobe-specific changes in AR expression in the adult gland.(ABSTRACT TRUNCATED AT 400 WORDS)