Biochemical and histological studies on prostates in castrated dogs after treatment with androstanediol, oestradiol and cyproterone acetate

Prostate histological investigation in rats exposed to bisphenol a and phytochemicals during the perinatal period and subjected to hormonal stimulus in adulthood

Bisphenol A (BPA) is an environmentally dispersed chemical associated with tumor development. Phytochemicals such as indole-3-carbinol (I3C) and genistein (GEN) have chemoprotective effects on tumor cells. Thus, this study aimed to evaluate the prostatic morphological aspects of rats exposed to BPA, GEN, and I3C during the perinatal period and submitted to hormonal stimulus in adulthood. Blood was collected to obtain hormone concentrations. Slides stained with hematoxylin & eosin, and picrosirius were subjected to fractal, stereological, morphometric, and collagen quantification analysis. I3C decreased the plasma dihydrotestosterone levels, and both phytochemicals increased the plasma estrogen levels. Unlike phytochemicals, BPA did not alter any of the parameters evaluated. GEN reduced the epithelial height, while I3C increased the fractal dimension and stromal collagen. Although BPA did not alter the prostate morphology, the phytochemicals provided beneficial effects for the prostate histological organization in adult animals subjected to hormonal stimulus.

Role of Stromal Paracrine Signals in Proliferative Diseases of the Aging Human Prostate

Androgens are essential for the development, differentiation, growth, and function of the prostate through epithelial–stromal interactions. However, androgen concentrations in the hypertrophic human prostate decrease significantly with age, suggesting an inverse correlation between androgen levels and proliferative diseases of the aging prostate. In elderly males, age- and/or androgen-related stromal remodeling is spontaneously induced, i.e., increased fibroblast and myofibroblast numbers, but decreased smooth muscle cell numbers in the prostatic stroma. These fibroblasts produce not only growth factors, cytokines, and extracellular matrix proteins, but also microRNAs as stromal paracrine signals that stimulate prostate epithelial cell proliferation. Surgical or chemical castration is the standard systemic therapy for patients with advanced prostate cancer. Androgen deprivation therapy induces temporary remission, but the majority of patients eventually progress to castration-resistant prostate cancer, which is associated with a high mortality rate. Androgen deprivation therapy-induced stromal remodeling may be involved in the development and progression of castration-resistant prostate cancer. In the tumor microenvironment, activated fibroblasts stimulating prostate cancer cell proliferation are called carcinoma-associated fibroblasts. In this review, we summarize the role of stromal paracrine signals in proliferative diseases of the aging human prostate and discuss the potential clinical applications of carcinoma-associated fibroblast-derived exosomal microRNAs as promising biomarkers.

Effect of transforming growth factor α overexpression on urogenital organ development in mouse

Transforming growth factor-α (TGFα) promotes cell proliferation by binding to the epidermal growth factor receptor (EGFR). TGFα and EGFR overexpression have been reported in various human cancers. However, whether TGFα induces cancer by itself is unknown in urogenital organs. To investigate whether TGFα overexpression induces carcinogenesis in urogenital organs, we analyzed the phenotypes of urogenital organs in male TGFα transgenic (TG) mice of the CD1 strain. Urogenital organs including the kidney, bladder, prostate, seminal vesicles, testes, and epididymis were isolated from 4- to 48-week-old TGFα TG and wild-type (WT) CD1 mice. Prostates were separated into anterior prostate (AP), dorsolateral prostate (DLP), and ventral prostate (VP). Neither tumor formation nor epithelial hyperplasia was observed in the TGFα TG mouse urogenital organs that we have investigated. Histopathologically, in prostate, we found an increased number of p63-positive basal epithelial cells in the TGFα TG mice AP and DLP. There was no morphological change in the stromal component, such as hypercellular stroma or fibrosis. However, bladder weight was greater in TGFα TG mice than that in WT mice, and distended bladders were observed macroscopically in 19 of 20 TGFα TG mice over 20 weeks of age. Ki67 labeling index was increased significantly in the TGFα TG mouse urethral epithelium, whereas neither epithelial hyperplasia nor hypertrophy was observed. In conclusion, our results suggest that TGFα overexpression in mouse urogenital organs alone may not be responsible for tumor formation and epithelial hyperplasia, but is involved in bladder outlet obstruction.

Expression of enzymes involved in estrogen metabolism in human prostate

There is evidence that estrogens can directly modulate human prostate cell activity. It has also been shown that cultured human prostate cancer LNCaP can synthesize the active estrogen estradiol (E2). To elucidate the metabolism of estrogens in the human prostate, we have studied the expression of enzymes involved in the formation and inactivation of estrogens at the cellular level. 17beta-Hydroxysteroid dehydrogenase (17beta-HSD) types 1, 2, 4, 7, and 12, as well as aromatase mRNA and protein expressions, were studied in benign prostatic hyperplasia (BPH) specimens using in situ hybridization and immunohistochemistry. For 17beta-HSD type 4, only in situ hybridization studies were performed. Identical results were obtained with in situ hybridization and immunohistochemistry. All the enzymes studied were shown to be expressed in both epithelial and stromal cells, with the exception of 17beta-HSD types 4 and 7, which were detected only in the epithelial cells. On the basis of our previous results, showing that 3beta-HSD and 17beta-HSD type 5 are expressed in human prostate, and of the present data, it can be concluded that the human prostate expresses all the enzymes involved in the conversion of circulating dehydroepiandrosterone (DHEA) to E2. The local biosynthesis of E2 might be involved in the development and/or progression of prostate pathology such as BPH and prostate cancer through modulation of estrogen receptors, which are also expressed in epithelial and stromal cells.

Dopamine agonists, anti-progestins, anti-androgens, long-term-release GnRH agonists and anti-estrogens in canine reproduction: a review

Over the last 10 years, new drugs have been applied to canine reproduction, widening the spectrum of therapeutic possibilities for diseases that were previously surgically treated, and facilitating better control of the estrous cycle and fertility. Some are not approved for use in dogs; their use is experimental and further clinical trials are necessary. Dopamine agonists such as cabergoline, bromocriptine or metergoline are ergoderivative alkaloids that exert an anti-prolactinergic effect via stimulation of D2 pituitary receptors or inhibition of central serotoninergic ones. Their main indication is suppression of lactation. Anti-prolactinergic compounds have also been successfully used for pregnancy termination and shortening of interestrous intervals. Anti-progestins, (e.g. mifepristone and aglepristone) are synthetic steroids that bind with high affinity to progesterone (P4) receptors, preventing P4 from exerting its biological effects. Anti-progestins have been indicated in P4-dependent conditions, such as pregnancy termination, induction of parturition and the medical treatment of pyometra. Several groups of drugs have been described to have anti-androgenic properties through different mechanisms of action: progestins, receptor binding anti-androgens (e.g. flutamide), competitive enzyme inhibitors (e.g. finasteride), aromatase inhibitors, and GnRH agonists. Their main application is medical treatment of benign prostatic hyperplasia. Long-term release formulations of GnRH agonists (e.g. leuprolide or deslorelin acetate) postponed puberty and reversibly suppressed reproductive function in male and female dogs for periods exceeding 1 year. Anti-estrogens (e.g. clomiphene and tamoxifen citrate) are synthetic non-steroidal type I anti-estrogenic compounds that competitively block estrogen receptors with a combined antagonist-agonistic effect. In dogs, their action is more agonistic than antagonistic.

Early effects of estrogen on the rat ventral prostate

Complex interactions between androgen and estrogen (E2) regulate prostatic development and physiology. We analyzed the early effects of a high single dose of E2 (25 mg/kg body weight) and castration (separately or combined) on the adult 90-day-old male Wistar rat ventral prostate. Androgen levels, prostate weight, and the variation in the relative and absolute volume of tissue compartments and apoptotic indices were determined for 7 days. Castration and exogenous E2 markedly reduced ventral prostate weight (about 50% of the control), with a significant reduction in the epithelial compartment and increased stroma. The final volume of the epithelium was identical at day 7 for all treatments (58.5% of the control). However, E2 had an immediate effect, causing a reduction in epithelial volume as early as day 1. An increase in smooth muscle cell volume resulted from the concentration of these cells around the regressing epithelium. The treatments resulted in differential kinetics in epithelial cell apoptosis. Castration led to a peak in apoptosis at day 3, with 5% of the epithelial cells presenting signs of apoptosis, whereas E2 caused an immediate increase (observed on day 1) and a sustained (up to day 7) effect. E2 administration to castrated rats significantly increased the level of apoptosis by day 3, reaching 9% of the epithelial cells. The divergent kinetics between treatments resulted in the same levels of epithelial regression after 7 days (approximately 30% of control). These results show that E2 has an immediate and possibly direct effect on the prostate, and anticipates epithelial cell death before reducing testosterone to levels as low as those of castrated rats. In addition, E2 and androgen deprivation apparently cause epithelial cell death by distinct and independent pathways.

Identification of genes involved in estrogenic action in the human prostate using microarray analysis

Estrogens have profound effects on the developing prostate and are suspected to contribute to the development of benign prostatic hyperplasia, but the mechanism by which this hormone elicits its regulatory function still remains largely unknown. Using complementary RNA microarrays comprising approximately 10,000 oligonucleotide gene targets we compared differences in mRNA expression of estradiol-treated and untreated prostatic stromal cells in vitro. Based on a threshold of greater than twofold change, 228, 241, and 464 of the expressed genes were found to be regulated by estradiol after 10, 24, and 48 h of treatment, respectively. The secondary analysis of one estradiol-activated transcript, namely lipopolysaccharide-binding protein, and four estradiol-repressed genes, namely ras homolog gene family member E (RhoE/Rnd3), ubiquitin thiolesterase, interleukin 6, and interleukin 8 (IL-8), by real-time quantitative PCR confirmed the results of the microarray analysis. Moreover, IL-8 and RhoE were found to be down-regulated by estradiol at the protein level as well. We identified a set of genes involved in a wide range of cellular functions that are potentially important for understanding the molecular basis of estradiol action in the prostate.

Effects of estradiol on prostate epithelial cells in the castrated rat

There is evidence that estrogens can modulate the activity of prostate epithelial cells. To determine whether estradiol can have a direct influence on rat prostate, this study examined the effects of estradiol-17beta (E(2)) administered alone or in combination with dihydrotestosterone (DHT) to castrated rats for 3 weeks on prostate binding protein (PBP) C1 mRNA expression and androgen receptor (AR) localization. PBP C1 mRNA levels were measured by semi-quantitative in situ hybridization using a (35)S-labeled cDNA probe. In intact animals, strong hybridization signal could be observed in prostate sections after 12 hr of exposure to Kodak X-Omat films. In castrated rats, no PBP C1 mRNA could be detected even with longer exposure times, an effect that was prevented by administration of DHT. E(2) administered alone induced a detectable hybridization signal, and the concomitant administration of E(2) and DHT induced an increase in PBP C1 mRNA that significantly exceeded that obtained in animals that received only DHT. In prostate epithelial cells of intact animals, AR immunostaining was restricted to the nucleus. In castrated animals the alveoli were decreased in size and the epithelial cells were atrophied. AR staining was weak and was detected in both cytoplasm and nucleus. DHT administration completely obviated the effect of castration on epithelial cell histology and on AR immunostaining distribution and intensity. Interestingly, E(2) administration alone induced moderate hypertrophy of epithelial cells compared to the histological appearance of cells in untreated castrated rats. Moreover, in E(2)-treated animals the nuclear staining was much stronger than that detected in untreated castrated rats, whereas the cytoplasmic staining was not modified by the treatment. In animals that received both DHT and E(2), the staining was similar to that seen in DHT-treated rats. These results suggest that E(2) can influence the activity of rat prostate epithelial cells by mechanisms that remain to be fully clarified.

High plasma estradiol-17beta levels in dogs with benign prostatic hyperplasia and azoospermia

The semen quality of 22 dogs (4 to 7 years old) with benign prostatic hyperplasia (BPH) was examined at the hospital of our university, and 4 of the 22 BPH dogs were diagnosed as azoospermic. The mean peripheral plasma estradiol-17beta (E2) level (17.3 pg/ml) of the 18 BPH dogs with spermatogenic function was higher than that of 5 normal male dogs and their mean T level (1.7 ng/ml) was lower. The mean E2 level (27.3 pg/ml) of the 4 BPH dogs with azoospermia was significantly higher than the value in the BPH dogs with spermatogenic function (P<0.01), and the mean T level (1.1 ng/ml) was significantly lower (P<0.05). Five normal male dogs were given 10 intramuscular injections of estradiol benzoate (E2B) 5 microg/kg, at 3-day intervals to investigate the relationship between high plasma E2 levels and the cause of the BPH and azoospermia. Their testes and prostates were measured and biopsied both before and 30 days after the start of E2B injections. At 30 days after the start of the E2B injections, the mean peripheral plasma T levels had decreased by half, and the mean testicular volume had decreased to 88% of original volume. The numbers of spermatocytes, spermatids, and spermatozoa in the seminiferous tubules of all of the dogs were significantly lower (P<0.05, 0.01). In addition, the mean prostatic volume increased to 130%, the mean height of the glandular epithelium decreased, and the glandular lumen became increased in diameter. These findings indicate that both BPH and serious spermatogenic dysfunction may be simultaneously induced by protracted high plasma E2 levels in dogs.

Evidence that epithelial and mesenchymal estrogen receptor-alpha mediates effects of estrogen on prostatic epithelium

In combination with androgens, estrogens can induce aberrant growth and malignancy of the prostate gland. Estrogen action is mediated through two receptor subtypes: estrogen receptors alpha (ERalpha) and beta (ERbeta). Wild-type (wt) and transgenic mice lacking a functional ERalpha (alphaERKO) or ERbeta (betaERKO) were treated with the synthetic estrogen diethylstilbestrol (DES). DES induced prostatic squamous metaplasia (SQM) in wt and betaERKO but not in alphaERKO mice, indicating an essential role for ERalpha, but not ERbeta, in the induction of SQM of prostatic epithelium. In order to determine the respective roles of epithelial and stromal ERalpha in this response, the following tissue recombinants were constructed with prostatic epithelia (E) and stroma (S) from wt and ERKO mice: wt-S+wt-E, alphaERKO-S+alphaERKO-E, wt-S+alphaERKO-E, and alphaERKO-S+wt-E. A metaplastic response to DES was observed in wt-S+wt-E tissue recombinants. This response to DES involved multilayering of basal epithelial cells, expression of cytokeratin 10, and up-regulation of the progesterone receptor. Tissue recombinants containing alphaERKO-E and/or -S (alphaERKO-S+alphaERKO-E, wt-S+alphaERKO-E, and alphaERKO-S+wt-E) failed to respond to DES. Therefore, full and uniform epithelial SQM requires ERalpha in the epithelium and stroma. These results provide a novel insight into the cell-cell interactions mediating estrogen action in the prostate via ERalpha.

Estradiol causes a dose-dependent stimulation of prostate growth in castrated beagle dogs

BACKGROUND

Previous studies have shown that chronic treatment of castrate dogs with androgen and estrogen results in significant prostate growth. Estrogen treatment of castrate dogs in the absence of androgen has resulted in conflicting data as reported by several authors. The purpose of this experiment was to evaluate the effect of a physiological dose of estradiol on prostate growth in dogs, using ultrasound to study size changes over time.

METHODS

Dogs (n = 25) were randomly divided into groups (n = 5) and treated as follows: castration alone (CC), castration plus low dose estradiol (E(2) low), castration plus high estradiol (E(2) high), castration plus estradiol and androstanediol (E(2)A), or no treatment (normal controls, NC). Silastic implants containing 5alpha-androstan-3alpha-17beta-diol (3alphadiol), and/or 17beta-estradiol were used for continous delivery of steroids. Prostate volume was measured by transrectal ultrasonography, and blood was drawn for hormone and sex hormone binding globulin (SHBG) determinations.

RESULTS

Results show that serum estradiol and SHBG levels were fairly constant over 12 weeks in all groups. Estradiol-treated groups had mean serum estradiol values of approximately 40 and 60 pg/ml, respectively. Initially, all groups had similar prostate volumes. Over 12 weeks the castrate dogs had a decline in prostate volume, whereas the intact dogs and those treated with E(2) and 3alpha-diol maintained a constant prostate volume. Estradiol treatment caused a large, late onset (week 7), dose-dependent increase in prostate volume relative to the intact group (P < 0.01). At 12 weeks, animals were euthanized and prostates weighed. The mean prostate weights in each group were: NC 14.8 +/- 2. 9, CC 2.4 +/- 0.5, E(2)A 9.7 +/- 2.0, E(2) low 21.7 +/- 4.3, and E(2) high 63.6 +/- 12.6 g (geometric mean +/- SEM). Histologically, prostates of estrogen-treated dogs showed metaplastic squamous epithelium.

CONCLUSIONS

These results demonstrate that estradiol causes marked dose-dependent stimulation of prostate growth in the castrate dog.

Chlormadinone acetate pellet implantation plus short-term oral administration in dogs with benign prostatic hypertrophy

Eight beagles with benign prostatic hypertrophy (BPH) were treated by subcutaneous implantation of pellets containing 10 mg/kg chlormadinone acetate (CMA), a synthetic anti-androgen, plus daily oral administration of CMA at 2 mg/kg per day for 7 days as a therapy for BPH. Prostatic and testicular size were measured and prostatic and testicular biopsies were performed by laparotomy before and after CMA treatment. Plasma levels of luteininzing hormone (LH), testosterone and oestradiol were also measured. The clinical signs of BPH, for example haematuria and dysuria, resolved within 1 week of treatment. Mean prostatic volume decreased to 56% of the pretreatment value. At 40 weeks after treatment, prostatic volume had decreased by 36%. Histological examination of the prostate 1 week after treatment revealed reduction in diameter of the alveoli and in height of the glandular epithelium. Degeneration and atrophy of the glands were marked 4-12 weeks after treatment. In the testis, the diameter of seminiferous tubules and the number of germ cells in the seminiferous tubules had decreased markedly at 12 and 24 weeks after treatment. Although plasma LH concentrations did not undergo any marked fluctuations after CMA treatment, levels of testosterone and oestradiol were lower than before treatment. The results indicate that implantation of 10 mg/kg CMA, plus 7-day oral administration of 2 mg/kg CMA, bring about resolution of the clinical signs and marked reduction in prostatic volume within 1 week of treatment.

Active cell death in hormone-dependent tissues

Active cell death (ACD) in hormone-dependent tissues such as the prostate and mammary gland is readily induced by hormone ablation and by treatment with anti-androgens or anti-estrogens, calcium channel agonists and TGF beta. These agents induce a variety of genes within the hormone-dependent epithelial cells including TRPM-2, transglutaminase, poly(ADP-ribose) polymerase, Hsp27 and several other unidentified genes. Not all epithelial cells in the glands are equally sensitive to the induction of ACD. In the prostate, the secretory epithelial cells that are sensitive to hormone ablation are localized in the distal region of the prostatic ducts, and are in direct contact with the neighboring stroma. In contrast, the epithelial cells in the proximal regions of the ducts are more resistant to hormone ablation, probably because the permissive effects of the stroma are attenuated by the presence of the basal epithelial cells, which are intercalated between the epithelium and stroma. The underlying biology of ACD in prostate and mammary glands, and its relevance to hormone resistance, is discussed in this review.

Estrogen-induced morphological and immunohistochemical changes in stroma and epithelium of rat ventral prostate

Prostatic smooth muscle cells have been regarded to play a major pathogenetic role during the development of benign prostatic hyperplasia (BPH) in elderly men. Altered hormonal signals (increased estrogen) have been made responsible for the "metabolic" transformation of prostatic smooth muscle cells, which were thought to produce increased amounts of connective tissue fibers observed in BPH. In order to find out the role of metabolically "activated" smooth muscle cells, hormone stimulation experiments were performed in male rats. The effects of androgen deprivation and estrogen stimulation were recorded by semiquantitative analysis of intermediate and myofilament proteins in stromal smooth muscle cells. In castrated or estrogen-treated or estrogen-treated and castrated animals, the reduction of the glandular lumen is the most obvious morphological alteration, accompanied by an increase in connective tissue. Regressive changes occurred most rapidly in castrated animals (already within the first week), slower in castrated estrogen-treated animals and still slower in normal estrogen-treated animals. Regression of the epithelium was accompanied by a marked decrease in immunoreactivity for prostatic binding protein (PBP) in castrated animals, while PBP immunoreactivity in estrogenized animals was retained for up to 6 weeks. Smooth muscle cells became atrophic in castrated animals. This effect was attenuated in estrogen-treated animals. There was no indication for enhanced collagen synthesis by smooth muscle cells. Actin and desmin-immunoreactivity were only slightly altered in experimental animals and showed a changed distribution pattern. Prostatic smooth muscle cells respond less markedly to hormonal alterations than do the fibroblasts.

DNA flow cytometric study of the hyperplastic and neoplastic canine prostate

Flow cytometric DNA measurements were carried out on 45 formalin-fixed, paraffin-embedded canine prostate tissues. The tissues were categorized as normal, hyperplastic, or neoplastic on the basis of light microscopic examination, and DNA ploidy was compared with histologic classification. Ten normal prostate samples showed diploid DNA histograms, but with proliferation greater than that found in the normal human prostate. Thirteen specimens of benign prostate hyperplasia showed diploid or near-diploid DNA histograms. Of 22 prostatic carcinomas, 12 were diploid and 10 were aneuploid, with the majority of the aneuploidy being near-triploid. The frequency of DNA aneuploidy recognized in canine prostatic carcinoma is similar to findings in human prostatic carcinoma if all their grades of malignancy are included.

Antiandrogenic substances in the management of prostatic cancer

Endocrine-active and pure antiandrogens have different mechanisms of action and different endocrinological effects in the intact male. With pure antiandrogens as a monotherapy an elevation of plasma testosterone occurs which probably leads to the preservation of potency, the clinical significance of which in the management of prostatic carcinoma is not known. Plasma testosterone is reduced to pretreatment levels after 12 months. Longer observations are not available. In total androgen suppression regimens both types of antiandrogens have been shown in prospective trials to be at least equally effective as standard treatment. The clinical effectiveness of CPA alone in prostatic cancer has been shown to be equal to that of DES 1 mg tid. Sufficiently large prospective studies on flutamide alone in comparison to standard treatment have not been carried out. The use of antiandrogens is recommended during the initial 4 weeks of management of prostatic carcinoma patients with LH-RH agonists to prevent disease flare-up and to achieve higher early response rates in selective patients.

Effect of the steroidal androgen receptor antagonist Win 49,596 on steroid-induced benign prostatic hyperplasia in the castrate beagle dog

The effects of the steroidal androgen receptor antagonist Win 49,596 on steroid-induced prostatic growth, histomorphology, and secretory function were studied in the castrate male beagle dog. At oral doses ranging from 0.625 to 40 mg/kg/day for 12 weeks, Win 49,596 inhibited prostatic growth in terms of both weight and total DNA in a dose-dependent manner. In addition, both the incidence and severity of diffuse glandular hyperplasia/hypertrophy were dose-dependently inhibited by Win 49,596, resulting in diffuse glandular atrophy. Prostatic secretory function was also inhibited by Win 49,596 treatment. The effects of Win 49,596 at a dosage of 40 mg/kg/day were similar to that observed for the nonsteroidal androgen receptor antagonist flutamide at 10 mg/kg/day. Oral administration of Win 49,596 to castrate dogs at a dosage of 40 mg/kg/day for 12 weeks failed to produce any evidence of agonist activity. These results demonstrate that Win 49,596 prevented the experimental induction of benign prostatic hyperplasia in dogs and suggest that on further evaluation this compound may be efficacious in the treatment of the human disease.

Antiandrogens alone or in combination for treatment of prostate cancer: the European experience

In Europe, antiandrogens have been used for many years to treat prostate cancer, either as monotherapy or as part of a "combination therapy" with either surgical or chemical castration. However, considerable debate still exists regarding the relative benefits of combination therapy versus antiandrogen monotherapy or castration alone. This article reviews the European experience with antiandrogen therapy, including the personal experiences of the authors.

Dose-dependent hormonal induction of benign prostatic hyperplasia (BPH) in castrated dogs

A model for the dose-dependent hormonal induction of benign prostatic hyperplasia (BPH) in castrated dogs has been established using subcutaneously implanted Silastic capsules containing 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) and estradiol-17 beta. In vivo release rates per capsule approximated 122.0 +/- 4.2 micrograms 3 alpha-diol and 22.7 +/- 0.8 micrograms estradiol per day based on in vitro studies and resulted in dose-dependent increases in serum 3 alpha-diol and dihydrotestosterone concentrations. The implantation of castrated dogs with either 10 or 20 Silastic capsules containing 3 alpha-diol and one capsule containing estradiol or the intramuscular injection of 3 alpha-diol (75 mg/week) and estradiol (0.75 mg/week) for 99 days significantly increased (P less than .01) prostatic weights and total prostatic DNA over intact controls. These treatments also resulted in a histomorphological pattern similar to that observed in dogs with the glandular form of spontaneous BPH. In addition, normal prostatic secretory function as determined by semen volume was maintained in these dogs. Although subcutaneous implantation of five Silastic capsules containing 3 alpha-diol and one capsule containing estradiol into castrated dogs resulted in prostatic weights and total prostatic DNA that were similar (P less than .10) to intact controls, these prostates were characterized histomorphologically by glandular atrophy and squamous metaplasia. Furthermore, prostatic secretory function was decreased (P less than .05) in these animals compared with intact controls at 3 months of treatment. This study has led to the development of a model of steroid-induced BPH that will facilitate the evaluation of competitive androgen-receptor antagonists in the dog.

Aromatase inhibition in the dog. II. Effect on growth, function, and pathology of the prostate

To evaluate the role of aromatase inhibitors in the treatment of benign prostatic hyperplasia (BPH), the effects of a potent, oral, nonsteroidal aromatase inhibitor [4-(5,6,7,8-tetrahydroimidazo[1,5a]pyridin-5yl)benzonitrile; CGS-16949A, CIBA-GEIGY] on canine BPH have been studied. Twelve mature beagles with enlarged prostates were divided into two groups of similar age, prostatic size, and prostatic histology. Dogs were given either CGS-16949A at a dosage of 2.5 mg./kg./day p.o. (n = 6) or an oral placebo (n = 6) for 25 weeks. Treatment with aromatase inhibitor had no significant effect on prostatic weight nor on total DNA content when compared to controls (p greater than 0.1). Semen volume did not change with treatment, and prostatic tissue concentrations of testosterone, dihydrotestosterone (DHT), and 5 alpha-androstan-3 alpha,17 beta-diol (3 alpha-diol) were similar for the treated and control beagles (p greater than 0.1). Protein concentration in the ejaculate, however, was significantly greater for the dogs receiving CGS-16949A (p less than 0.01). Histologically, there was no difference in the incidence or type of BPH between the two treatment groups. Beagles treated with aromatase inhibitor, however, did have a more severe inflammatory infiltrate of the prostatic parenchyma than the control dogs (p less than 0.01). The mean serum testosterone concentration for the beagles treated with aromatase inhibitor was 10 times greater than that for the control animals (p less than 0.01). The endocrine effect of this aromatase inhibitor in the male canine is presented in the preceding paper. Taken together, these results suggest that inhibition of endogenous aromatase activity is not an effective treatment for spontaneous BPH in the intact canine.

Aromatase inhibition in the dog. I. Effect on serum LH, serum testosterone concentrations, testicular secretions and spermatogenesis

Chronic treatment of intact male beagles with an orally active nonsteroidal aromatase inhibitor (4-(5,6,7,8-tetrahydroimidazo [1,5a] pyridin-5-yl) benzonitrile hydrochloride; CGS 16949; CIBA-GEIGY) at a dosage of 2.5 mg./kg. per day for six months resulted in increased (p less than 0.01) serum LH and testosterone concentrations compared to placebo-fed controls. The increases in serum LH and testosterone concentrations occurred by one week of treatment and were maintained over the six month period. Testes of CGS 16949A fed dogs obtained at termination of the experiment when perfused in vitro in the presence of a maximally stimulating concentration of LH secreted nondetectable amounts of estradiol and estrone and higher (p less than 0.01) amounts of testosterone, androstenedione and dihydrotestosterone than testes of control dogs. Despite these changes in androgen secretion there was no evidence on any effect of aromatase inhibition upon spermatogenesis. These data support the hypothesis that in the dog, estrogens play a major role in negative feedback of the hypothalamic-pituitary-testicular axis.

Study of the effect of an anti-androgen (oxendolone) on experimentally induced canine prostatic hyperplasia. I. Morphological analysis

To investigate the effect of anti-androgens on BPH, Oxendolone (OXD), a pure anti-androgen, was tested in experimentally induced BPH in 17 beagle dogs, alone or in combination with medroxyprogesterone acetate (MPA) which displays both anti-androgenic and anti-estrogenic activity. The relatively early stage of canine BPH was induced by administration of 3 alpha-androstanediol (3 alpha-A) plus estradiol (E2) for 6 months and followed by testosterone propionate (TP) plus E2 for another 6 months during the anti-androgenic treatment. By the manipulation with T, a decrease in volume of glandular component associated with a relative increase in stromal tissue was achieved, which mimics human BPH histology. The prostate substituted with T and E2, however, gradually decreased in size. Therefore the effect of OXD or OXD + MPA was not significant against the untreated controls (T-E control). The weight of the prostate in these OXD +/- MPA groups was however significantly reduced as compared to that of BPH controls which received 3 alpha-A and E2 throughout the experimental period. On histological examination, atrophic changes were observed in the hormone-treated groups compared to the T-E control. The finding was the most striking in the OXD + MPA group with small non-involuted acini scattered in the abundant stomal tissue. This was almost identical to the appearances of castrated control groups. Atrophy may be due not only to the anti-androgenic but also to the anti-estrogenic property of MPA. A report on the hormonal background of this experiment will appear in the second article.

Investigations of the estrogen (ER-ICA-test) and the progesterone receptor in the prostate and prostatic carcinoma on immunohistochemical basis

Estrogen (ER) and Progesterone receptors (PR) were demonstrated immunohistochemically on frozen sections from 11 prostatectomy and 7 cystoprostatectomy specimens in the nuclei of various cell types. The periglandular fibrocytes and smooth muscle cells were extensively positive, the interglandular stromal cells were only partly so. Normal basal cells stained focally positive, hyperplastic basal cells stained extensively. The glandular secretory epithelium and atrophic glands were negative. The same findings were obtained in hyperplastic nodules. Both ER and PR also occurred in the urothelium of central prostatic ducts and of the prostatic urethra. The fibrous stroma around the ejaculatory ducts and seminal vesicles was extensively positive while the epithelium was negative. The smooth musculature of the seminal vesicles was only partly positive. On large field sections, the ER as well as the PR were numerically equally distributed throughout the inner zone of the prostate and the prostate proper. 12 prostatic carcinomas (G I-G III) were ER- and PR-negative. Estrogens may contribute to nodular hyperplasia by triggering a stromal proliferation with a secondary inductive epithelial growth. Obviously they do not act directly on prostatic carcinoma but inhibit growth via the hypophyseal-testicular axis. The biological significance of the PR in the prostate is unknown.

5 alpha-reductase activity in epithelium and stroma of prostates from intact and castrated dogs treated with androstenedione, the aromatase inhibitor 1-methyl-1,4-androstadiene-3,17-dione, and cyproterone acetate

In addition to the histology of epithelial and stromal elements of prostates from intact dogs (group 0) and castrated dogs (group I), the latter of which were treated with androstenedione (group II), androstenedione plus the aromatase inhibitor 1-methyl-1,4-androstadiene-3,17-dione (group III), or androstenedione plus aromatase inhibitor and cyproterone acetate (group IV) (Habenicht and El Etreby: The Prostate 11:133-143, 1987) it was of interest to study the influence of such in vivo treatment on the prostatic 5 alpha-reductase, which is responsible for the cellular conversion of testosterone to 5 alpha-dihydrotestosterone. Michaelis constants (KM) and maximal activities (Vmax) of 5 alpha-reductase were determined under optimized incubation conditions in mechanically separated epithelium and stroma. The metabolites were separated by high-performance liquid chromatography and determined radiometrically. The main results were: 1) The mean KM (nM +/- SEM) was significantly (P less than .001) higher in epithelium (892 +/- 132) than stroma (70 +/- 11). The same was true concerning the Vmax (pmol.mg protein-1.h-1 +/- SEM) in epithelium (54.6 +/- 5.8) as compared to stroma (13.0 +/- 2.0). 2) No specific in vivo or in vitro effect of the aromatase inhibitor on the KM and Vmax data was found. 3) In prostates of intact dogs and dogs of group II the proportion of epithelial 5 alpha-reductase exceeded distinctly that of stromal 5 alpha-reductase. 4) In groups I, III, and IV the proportion of epithelial 5 alpha-reductase was rather low. These data were discussed in the light of the histological findings.

Pharmacologically induced ultrastructural and immunohistochemical changes in the prostate of the castrated dog

The effects of an aromatase inhibitor and of an antiandrogen on the ultrastructure and the expression of a secretory protein (acid phosphatase) and marker proteins for basal cells (keratin) and fibroblasts (vimentin) were studied in the prostate of castrated, androstenedione-treated dogs. Androstenedione treatment partially restored the normal appearance of the gland and also some secretory activity. In the central portion of the gland, basal cell hyperplasia developed instead of secretory activity after androstenedione treatment. Administration of the aromatase inhibitor reduced the number of secretory cells but did not completely suppress the latter. There was some proliferation of the connective tissue surrounding the atrophic acini. Combined treatment with aromatase inhibitor and antiandrogen resulted in a general atrophy of prostatic acini that was less intense relative to the changes observed after castration. Residual secretory activity, detected in specimens treated exclusively with aromatase inhibitor, were lacking after combined treatment. The influence of all regimens on the ultrastructure of smooth muscle cells was comparably discrete, whereas regional differences in the arrangement pattern of the epithelium and the fibromuscular stroma were impressive. The ultrastructural findings support previous results of a synergic inhibitory effect of aromatase inhibitor and antiandrogens on the canine prostate.

Immunocytochemical localization of estrogen receptors in spontaneous and experimentally induced canine benign prostatic hyperplasia

Estrogens are believed to play a critical role in the etiology of canine benign prostatic hyperplasia (BPH); however, the mechanism has not been elucidated. To gain insight into this problem, we investigated the immunocytochemical localization of estrogen receptors (ER) in normal prostates, spontaneous BPH, and experimentally induced BPH by using a monoclonal ER antibody (H222). In all canine prostates the majority of ER was localized in nuclei of the same histological components: (1) transitional epithelium and subjacent stroma of the prostatic urethra, (2) periurethral prostatic ductal epithelium, and (3) prostatic stroma. ER content in the stroma was highest in the periurethral region of the prostate. Among the different groups of dogs, differences in ER location were seen only in the glandular epithelium. No ER was found in the glandular epithelium of normal prostates of young untreated dogs. In striking contrast, glandular epithelium of spontaneous BPH contained specific nuclear ER staining, though this staining was heterogeneous and was observed in only a minority (less than 10%) of the acinar epithelial cells. ER-positive acini in BPH were located predominantly in the periurethral region. These data demonstrate anatomical and biochemical heterogeneity of prostatic components and indicate that the estrogen sensitivity of prostatic cells is heterogeneous. If estrogen does play a role in BPH, it appears to act selectively rather than uniformly throughout the prostate. We reasoned that if glandular epithelial ER are involved in the development of spontaneous BPH, one might expect to find the same location of ER in BPH that was induced experimentally by specific types of treatment with androgens +/- estradiol. However, among hormone-treated dogs the presence of ER-positive prostatic glandular epithelium varied with the type of hormonal treatment but did not correlate with the experimental induction of glandular BPH. Some treatment groups with induced BPH had ER-positive prostatic glandular epithelial nuclei (with the same extent and pattern of ER localization as in spontaneous BPH); however, other treatment groups with induced BPH had ER-negative glandular epithelium. These data indicate either that glandular epithelial ER may not be involved in the pathogenesis of canine BPH or that there may be different types of BPH that have different etiologies. Possible mechanisms by which estrogen may affect the canine prostate are discussed in light of these new data on ER location.

Dihydrotestosterone and 3 alpha-androstanediol dynamics in the normal, involuted, and hyperplastic canine prostate

Perfusion of canine prostatic tissue with [1, 2-3H] 5 alpha-androstane-3 alpha, 17 beta-diol and [4-14C] dihydrotestosterone and the measurement of the isotopic concentrations at the steady state were used to calculate the metabolic dynamics of these steroids by prostatic tissue obtained from normal, castrated or androgen-treated dogs. From the results it was concluded that: Entry of both steroids into the tissue was similar, and no saturation was observed with increasing concentrations of these androgens in the perfusion medium. In contrast, the entry of both steroids was reduced when the perfusion buffer was replaced with diluted plasma. Dihydrotestosterone in prostatic tissue was present in a diffusible form, whereas 3 alpha,17 beta-androstanediol was not. The conversion of 3 alpha, 17 beta-androstanediol to dihydrotestosterone was always higher than the conversion of dihydrotestosterone to 3 alpha, 17 beta-androstanediol; thus, the oxidative pathway was favored. The entry and uptake of both androgens was greatly reduced in those prostates excised from castrated dogs. The uptake of dihydrotestosterone by normal prostatic tissue was 3- to 6-fold higher than the uptake of 3 alpha, 17 beta-androstanediol. However, higher intratissular concentrations of dihydrotestosterone were obtained by increasing the concentration of 3 alpha, 17 beta-androstanediol perfused over that observed by increasing the concentration of dihydrotestosterone perfused. In the hyperplastic tissue, the entry, uptake and metabolism of the two androgens were similar to those observed in the normal gland, but their intratissular concentrations were found to be higher.

Anti-androgens do not alter androgen-dependent characteristics of acid phosphatase in the rat ventral prostate

When administered to intact adult male rats, cyproterone acetate (10 mg/day), flutamide (15 mg/day), or Compound I (1 mg/day) caused a significant decrease in the organ weight to body weight ratios, with a concomitant rise in the specific activity of prostatic acid phosphatase. These compounds do not affect two other markers of androgen activity in the prostate. Neither the percentage inhibition of acid phosphatase activity by tartrate nor the appearance of the secretory band of acid phosphatase on polyacrylamide gels was altered by the administration of anti-androgens. When administered to castrated rats given doses of 5 alpha-dihydrotestosterone (250-750 micrograms/day), flutamide (15 mg/day) was unable to alter the percentage inhibition of acid phosphatase activity by tartrate, or the pattern of activity on polyacrylamide gels. These results suggest that these anti-androgens affect only some of the androgen-dependent functions of the prostate.

Nonsteroidal serum factors involved in the regulation of the proliferation of canine prostatic epithelial cells in culture

Canine prostatic epithelial cells were cultured in primary monolayers in order to define those factors that induce a proliferative response at the cellular level. Cultures were performed in a serum-free medium or in a medium supplemented either with fetal bovine serum or dog serum in the presence or absence of several sex steroids (androstenedione, testosterone, dihydrotestosterone, 3 alpha- and 3 beta-androstanediols, epitestosterone, epidihydrotestosterone, estrone, estradiol, and progesterone). Cell proliferation was observed in the absence of serum and exogenous steroids. The rate of cell division was serum dependent and steroid independent. Pretreatment of sera with charcoal had no effect on their mitogenic activities. Cells maintained in an endocrine milieu prior to tissue dispersion and throughout the whole procedure proliferate to the same extent as those deprived of hormones, whether free of serum or added supplements. The addition of insulin (2 micrograms/ml), dog prolactin (up to 25 ng/ml) and zinc (10(-8) to 10(-2) M) in a serum-free medium did not induce cell responsiveness to steroids. Dihydrotestosterone, 3 alpha-androstanediol, and estradiol alone or in combinations known to induce the growth of the canine prostate in vivo were ineffective in vitro. The proliferative responses to sera were time and concentration dependent, and dog serum was more potent than fetal bovine serum. Thus, humoral factors other than steroids, prolactin, insulin, or zinc may be of importance in the activation of epithelial cells involved in the development of prostatic hyperplasia and adenocarcinoma.

Estradiol binding activity in epididymal cytosol of the turtle, Chrysemys picta

Estrogen binding activity was investigated in the epididymis of the turtle, Chrysemys picta using DNA-cellulose affinity chromatography. A component binding estradiol-17 beta specifically with high affinity (Kd:8.0 X 10(-10) M) and limited capacity (20 fmol/mg protein) was demonstrated in the epididymal cytosol. In addition, binding of estradiol-17 beta was sensitive to excess (100-fold) diethylstilbestrol or natural estrogens (estradiol-17 beta, estrone, and estriol) but not to progesterone or androgens (testosterone and 5 alpha-dihydrotestosterone). The specific estrogen binding macromolecules eluted from DNA-cellulose columns sedimented at 4-5 S in linear 5-20% sucrose gradients. These characteristics suggest the presence of an estrogen receptor in this androgen target organ.

Collagen and cellular proliferation in spontaneous canine benign prostatic hypertrophy

Towards defining an animal model for study of cellular as well as extracellular matrix accumulation in human benign hypertrophy (BPH), cell number and levels of collagen and zinc were measured in normal and spontaneously hypertrophied canine prostate glands. The increased gland weight in canine BPH was accompanied by increased contents of DNA, collagen and zinc. Concentrations of collagen and zinc in BPH did not differ from normal. These findings indicate that canine BPH involves true hyperplasia and may represent an overgrowth of normal cellular and extracellular components. Canine BPH may prove to be a useful animal model for study not only of cellular proliferation, but also of the connective tissue and zinc accumulation in the human disease.

Phenotypic modulation of the canine prostate after long-term treatment with androgens and estrogens

Fine structural alterations of the canine prostate induced by long-term treatment of castrated adult animals with estrogens and/or androgens and also in combination with antiandrogens and/or antiestrogens for six months have been studied with particular respect to their topographic location within the gland. Three major patterns of structural responses of the epithelium have been distinguished: squamous metaplasia, atrophy, and hypertrophy, while in stroma, regression, hypertrophy, or sclerosis were observed. In addition to cellular alterations of stromal fibrocytes and smooth muscle cells, characteristic changes in the arrangement, distribution, and pattern of the different stromal elements occurred. General squamous metaplasia of the epithelium and regressive alterations of stromal cells were most obvious in animals treated with estradiol plus androstanediol. Atrophy of the epithelium and stromal sclerosis were the salient features of antiandrogen-treated castrated animals, while hypertrophy or hyperplasia of both the epithelium and stroma was a major finding in androstanediol-substituted castrated animals. Combined treatment caused rather heterogeneous structural patterns seemingly dependent on the location within the gland. The results indicate that the prostatic epithelial cells dispose of a broad variety of structural reaction patterns that, in case of combined hormonal treatment, are expressed in a manner typical for their locations within the ductal system of the gland. However, with the exception of combined treatment with estradiol, tamoxifen, and androstanediol of castrated dogs, none of the experimental protocols used induced a morphologic response of the gland comparable to that seen in human benign prostatic hyperplasia. The canine prostate therefore is of rather limited value as a model for human BPH.

Fluid inhibition as a factor in estrogen-induced increase of prostatic weight in castrated rats

The mechanism by which estrogens inhibit castration atrophy has been investigated morphologically and biochemically utilizing ventral prostate from Copenhagen rats. The suppression of weight loss and gross edematous appearance of the prostate associated with the in vivo effect of 17 beta-estradiol (E2) could not be accounted for by DNA and protein synthesis. Increase in the fluid content in the tissues was confirmed by demonstration of significant increase in the ratio of wet/dry tissue weights. Light microscopy demonstrated that the main effects were on the stroma, characterized by large interglandular areas almost totally devoid of collagen resulting in an edematous appearance. Electron microscope studies showed an abundance of fluid localized adjacent to the capillary endothelium and some red blood cells indicating disturbances in capillary permeability. The combination of a prolactin secretion inhibiting agent with E2 alone, indicating an involvement of prolactin the estrogen effect. Differences in blood prolactin concentration between the strains of rats may influence the sensitivity of the prostate to estrogens.