Cross-species and interassay comparisons of phytoestrogen action

This paper compiles animal and human data on the biologic effects and exposure levels of phytoestrogens in order to identify areas of research in which direct species comparisons can be made. In vitro and in vivo assays of phytoestrogen action and potency are reviewed and compared to actions, dose-response relationships, and estimates of exposure in human subjects. Binding studies show that the isoflavonoid phytoestrogens are high-affinity ligands for estrogen receptors (ERs), especially ER beta, but have lower potency in whole-cell assays, perhaps because of interactions with binding proteins. Many other enzymatic actions require concentrations higher than those normally seen in plasma. In vivo data show that phytoestrogens have a wide range of biologic effects at doses and plasma concentrations seen with normal human diets. Significant in vivoresponses have been observed in animal and human tests for bone, breast, ovary, pituitary, vasculature, prostate, and serum lipids. The doses reported to be biologically active in humans (0.4--10 mg/kg body weight/day) are lower than the doses generally reported to be active in rodents (10--100 mg/kg body weight/day), although some studies have reported rodent responses at lower doses. However, available estimates of bioavailability and peak plasma levels in rodents and humans are more similar. Steroidogenesis and the hypothalamic-pituitary-gonadal axis appear to be important loci of phytoestrogen actions, but these inferences must be tentative because good dose-response data are not available for many end points. The similarity of reported proliferative and antiproliferative doses illustrates the need for fuller examination of dose-response relationships and multiple end points in assessing phytoestrogen actions.

Safety and tolerability of BufferGel, a novel vaginal microbicide, in women in the United States

BufferGel (ReProtect, LLC) is a vaginal gel with an acidic buffering action that was designed to prevent vaginal neutralization by semen. The purpose of this study was to evaluate the safety and tolerability of BufferGel (ReProtect, Limited Liability Company) applied vaginally either once or twice daily by 27 women who were at low risk for acquisition of human immunodeficiency virus (HIV). Participants initially used the product once daily for 14 days and then twice daily for 14 days; they underwent colposcopy before and after product exposure. BufferGel was well tolerated, although two-thirds of the participants reported at least 1 mild or moderate adverse experience. The most common adverse events were irritative genitourinary symptoms. Product use was discontinued after 3 adverse events. BufferGel was well tolerated in women at low risk for acquisition of HIV; toxicity was limited and occurred at frequencies similar to those in women who did not use any vaginal product and at levels lower than in women who used detergent-based microbicides.

Critical windows of exposure for children's health: the reproductive system in animals and humans

Drugs and environmental chemicals can adversely affect the reproductive system. Currently, available data indicate that the consequences of exposure depend on the nature of the chemical, its target, and the timing of exposure relative to critical windows in development of the reproductive system. The reproductive system is designed to produce gametes in far greater excess than would seem to be necessary for the survival of species. Ten to hundreds of millions of spermatozoa are generated daily by most adult male mammals, yet very few of these germ cells succeed in transmitting their genetic material to the next generation. Although the number of oocytes produced in mammalian females is more limited, and their production occurs only during fetal life, most ovaries contain several orders of magnitude more oocytes than ever will be fertilized. Toxicant exposures may affect critical events in the development of the reproductive system, ranging from early primordial germ cell determination to gonadal differentiation, gametogenesis, external genitalia, or signaling events regulating sexual behavior. Although there are differences between the human reproductive system and that of the usual animal models, such models have been extremely useful in assessing risks for key human reproductive and developmental processes. The objectives for future studies should include the elucidation of the specific cellular and molecular targets of known toxicants; the design of a systematic approach to the identification of reproductive toxicants; and the development of sensitive, specific, and predictive animal models, minimally invasive surrogate markers, or in vitro tests to assess reproductive system function during embryonic, postnatal, and adult life.

Workshop to identify critical windows of exposure for children's health: reproductive health in children and adolescents work group summary

This work group report addresses the central question: What are the critical windows during development (preconception through puberty) when exposure to xenobiotics may have the greatest adverse impact on subsequent reproductive health? The reproductive system develops in stages, with sex-specific organogenesis occurring prenatally and further maturational events occurring in the perinatal period and at puberty. Complex endocrine signals as well as other regulatory factors (genetics, growth factors) are involved at all stages. Evidence from animal models and human studies indicates that many specific events can be perturbed by a variety of toxicants, with endocrine-mediated mechanisms being the more widely studied. Prioritized research needs include basic studies on the cellular-molecular and endocrine regulation of sexual differentiation and development; increased efforts regarding potential adverse effects on development in females, including breast development; expanded animal studies on different classes of chemicals, comparing responses during development (prenatal and postnatal) with responses in adults; and, more extensive explorations regarding the reproductive biology and toxicology of puberty in humans.

Critical windows of exposure for children's health: the reproductive system in animals and humans

Drugs and environmental chemicals can adversely affect the reproductive system. Currently, available data indicate that the consequences of exposure depend on the nature of the chemical, its target, and the timing of exposure relative to critical windows in development of the reproductive system. The reproductive system is designed to produce gametes in far greater excess than would seem to be necessary for the survival of species. Ten to hundreds of millions of spermatozoa are generated daily by most adult male mammals, yet very few of these germ cells succeed in transmitting their genetic material to the next generation. Although the number of oocytes produced in mammalian females is more limited, and their production occurs only during fetal life, most ovaries contain several orders of magnitude more oocytes than ever will be fertilized. Toxicant exposures may affect critical events in the development of the reproductive system, ranging from early primordial germ cell determination to gonadal differentiation, gametogenesis, external genitalia, or signaling events regulating sexual behavior. Although there are differences between the human reproductive system and that of the usual animal models, such models have been extremely useful in assessing risks for key human reproductive and developmental processes. The objectives for future studies should include the elucidation of the specific cellular and molecular targets of known toxicants; the design of a systematic approach to the identification of reproductive toxicants; and the development of sensitive, specific, and predictive animal models, minimally invasive surrogate markers, or in vitro tests to assess reproductive system function during embryonic, postnatal, and adult life.

E-7869 (R-flurbiprofen) inhibits progression of prostate cancer in the TRAMP mouse

E-7869 (R-flurbiprofen) is a single enantiomer of a racemic nonsteroidal anti-inflammatory drug. E-7869 does not inhibit either cyclooxygenase-1 or cyclooxygenase-2. We used the transgenic adenocarcinoma mouse prostate (TRAMP) mouse, a prostate cancer model, to evaluate the effect of this drug on prostate cancer progression. Sixty 12-week-old male TRAMP mice were placed randomly into five groups. The animals were treated by daily oral gavage with vehicle (1% carboxymethylcellulose) or E-7869 for 18-weeks. During the course of the study, two diets were used. Three groups (vehicle, 15-mg/kg, and 20-mg/kg drug treatments) received a Teklad diet containing 2.4% saturated fat [a high saturated fat (HSF) diet], and two groups (vehicle and 20 mg/kg drug treatment) received an AIN-93G diet containing 1.05% saturated fat [a low saturated fat (LSF) diet]. At necropsy, the urogenital system and periaortic lymph nodes were removed and weighed. The prostate lobes, seminal vesicles, lungs, and periaortic lymph nodes were preserved and sectioned for histological evaluation. The lung and periaortic lymph nodes were graded as to the presence (+) or absence (-) of metastasis; the urogenital tissues were graded on a 1-6 scale for degree of neoplasia/carcinoma. For both diets, the urogenital wet weights and lymph node wet weights in the 20-mg/kg treatment groups were significantly lower as compared to vehicle control groups. In addition, treatment with 20 mg/kg E-7869 in the LSF diet group resulted in a significantly lower primary tumor incidence (P < 0.05) and reduced incidence of metastasis. In this treatment group, the reduced incidence of metastasis was not statistically significant because the LSF diet itself resulted in a remarkably lower incidence of metastasis in the vehicle control group (10% LSF versus 40% HSF). Treatment with 20 mg/kg E-7869 on the HSF diet resulted in a significantly lower incidence of metastasis (P < 0.05) and a reduction in the primary tumor incidence. These results suggest that E-7869 is a promising chemopreventive and treatment for human prostate cancer.

Ah receptor and ARNT protein and mRNA concentrations in rat prostate: effects of stage of development and 2,3,7, 8-tetrachlorodibenzo-p-dioxin treatment

Effects of stage of development and 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (ARNT) protein concentrations in reproductive organs of male rats were determined. AhR protein levels in developing rat ventral and dorsolateral prostate decreased with age, declining approximately 70% between Postnatal Days (PND) 1 and 21. ARNT protein levels also decreased with age in dorsolateral, but not ventral prostate. The developmental decreases in prostatic AhR and ARNT protein were associated with decreases in AhR and ARNT mRNA. AhR and ARNT protein concentrations in fetal urogenital sinus on Gestation Days (GD) 16, 18, and 20 were similar to levels in ventral prostate on PND 7. TCDD exposure of adult male rats (0.2, 1, 5, or 25 micrograms/kg po, 24 h) decreased AhR but not ARNT protein in ventral and dorsolateral prostate, vas deferens, and epididymis. In utero and lactational TCDD exposure (1.0 micrograms/kg dam po, GD 15) did not alter ARNT levels but reduced prostatic AhR protein levels on PND 7 and delayed the developmental decrease in AhR protein in ventral and dorsolateral prostate. Finally, pretreatment of rat pups for 24 h with TCDD (5 micrograms/kg ip) down-regulated prostatic AhR protein on PND 7, but not on PND 1. Thus, prostatic AhR and ARNT protein and mRNA levels are regulated with age, whereas only AhR protein concentration is altered by TCDD exposure. Because in utero and lactational TCDD exposure only decreased prostatic AhR on PND 7, it is unlikely that down-regulation of AhR is the mechanism by which perinatal TCDD exposure impairs prostate development.

[Induction of epidermal growth factor (EGF) in the urogenital sinus by a brief treatment with androgens]

We have investigated the induction of epidermal growth factor (EGF) in the urogenital sinus of fetal mice when the sinuses were cultured with testosterone. Immunofluorescence study revealed that almost no EGF is detectable in the pre-incubated sinuses, whereas EGF is induced in the sinus mesenchyme as early as 2 hours after the testosterone treatment. The results support the hypothesis that paracrine-like factors secreted from the sinus mesenchyme activated by androgens may be EGF or EGF-like growth factors that stimulate the sinus epithelium to induce prostatic buds.

Estradiol-releasing vaginal ring delivery system for urogenital atrophy. Experience over the past decade

OBJECTIVE

To critically assess the world literature on the efficacy and safety of the vaginal ring estradiol delivery system for the local treatment of urogenital atrophy due to hypoestrogenism.

STUDY DESIGN

Published data over the past decade on the vaginal ring delivery system were reviewed.

RESULTS

Data from comparative clinical trials indicate that the vaginal ring delivery system is comparable in efficacy, safety and tolerability to other vaginal delivery systems and may enhance compliance because of its ease of use.

CONCLUSION

The vaginal ring delivery system offers an alternative to other vaginal delivery systems with the advantages of accurate and sustained dosing and minimal need for patient intervention.

Effects on developmental landmarks and reproductive capability of 3,3',4,4'-tetrachlorobiphenyl and 3,3',4,4',5-pentachlorobiphenyl in offspring of rats exposed during pregnancy

1. Pregnant Wistar rats were treated orally with a single dose of 100 microg 3,3',4,4'-tetrachlorobiphenyl (PCB 77)/kg b.w. or 10 microg 3,3',4,4',5 pentachlorobiphenyl (PCB 126)/kg b.w. on day 15 of pregnancy. The control rats received peanut oil at the same day. Developmental landmarks were assessed in all offspring rats and reproductive effects of PCB 77 and PCB 126 on male offspring were studied on postnatal day 65 (at puberty) and on postnatal day 140 (at adulthood). 2. The ano-genital distance as well as the ratio ano-genital distance to body length was reduced in male pups of the PCB 126 group and the age at vaginal opening was significantly delayed in the female pups. 3. Testis, brain weights and daily sperm production were permanently increased and seminal vesicle weights were decreased in male offspring of the PCB 77 group. In male rats of PCB 126 group, the brain weights were permanently increased and ventral prostate weights permanently reduced. In both PCB groups, however, serum testosterone concentration was reduced only at adulthood. Additionally, the male rats of the PCB 126 group showed alterations in sexual behavior. In these rats the number of mounts with intromissions was significantly increased. 4. The results of this study show that PCB 126 elicits some TCDD-like reproductive effects after in utero exposure, while the reproductive effects of in utero exposure to PCB 77 on male offspring may be attributed to the neonatal hypothyroidism induced by the substance during early fetal development. Further studies using multiple doses and providing thyroid hormone data will be necessary to support this hypothesis.

The role of estrogen in female urinary incontinence and urogenital aging: a review

Urogenital aging is a complex of urogenital symptoms involving the lower urinary tract, the genital tract and the pelvic floor. These symptoms involve hypoestrogenism in the menopausal woman. This review concludes that irritative urinary and local vaginal symptoms are quite amenable to estrogen therapy. Urinary incontinence is thought to be benefited by treatment with estrogen, although controversy exists. There is a limited role for estrogen in problems of urogenital prolapse, rectal symptoms, and sexuality in menopause.

Endocrine mechanisms underlying reproductive toxicity in the developing rat chronically exposed to dietary lead

A dose-response study was conducted in a rat model to examine the effects of lifetime lead exposure on the development of the reproductive system and the endocrine mechanisms underlying these effects. Time-impregnated female Sprague-Dawley rats (n = 10-15/group) were exposed to lead acetate in the drinking water at levels of 0.05%, 0. 15%, or 0.45% (w/v) initiated on gestational day 5. At birth, litters were culled to four male and four female pups. Exposure of dams to lead was continued until weaning, following which, the pups continued to be exposed to lead acetate in drinking water until sacrifice. One male and one female pup from each litter were sacrificed at age 21, 35, 55, and 85 d. A significant dose-responsive decrease in birth weight and crown-to-rump length was observed in all lead-exposed litters. However, no marked effects were observed on anogenital distance/crown-to-rump length ratios. Lead exposure resulted in a delay in sexual maturity as measured by prostate weight in male pups and time of vaginal opening in female pups, which increased with lead dose. These disruptions in reproductive physiology were accompanied by a significant decrease in neonatal sex steroid levels and suppression of the plasma concentrations of testosterone (male) and estradiol (female) during puberty. In male pups, this was accompanied by a significant decrease in plasma luteinizing hormone (LH), elevated pituitary LH content, and a decrease in plasma testosterone/LH ratios at the highest dose. In female pups, although no effects were observed on plasma LH concentration, a similar significant elevation in pituitary LH content was observed during early puberty. Postpuberty, plasma LH and sex steroid concentrations were unaffected at any dose in spite of continued lead exposure. No significant effects were observed on epididymal sperm count in male pups at 85 d of age. In female pups, estrus cycling was only significantly disrupted at the highest lead dose. These data suggest that the reproductive axis is particularly sensitive to lead during specific developmental periods, resulting in delayed sexual maturation produced by suppression by sex steroid biosynthesis. The mechanisms underlying this appear to involve lead actions on both LH release and gonadal function. At low, environmentally relevant blood lead concentrations, adaptation to the continuous presence of the metal ion occurs and surprisingly little effect is observed on adult reproductive endocrinology and physiology.

Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 2. Effects of prenatal anti-androgens

Pregnant spotted hyaenas were treated with anti-androgens to interfere with the unusually masculine 'phallic' development that characterizes females of this species. The effects on genital morphology and plasma androgen concentrations of infants were studied during the first 6 months of life. Although there were consistent 'feminizing' effects of prenatal anti-androgen treatment on genital morphology in both sexes, such exposure did not produce males with extreme hypospadia, as it does in other species, nor did it produce females with a 'typical' mammalian clitoris and external vagina. 'Feminization' of males resulted in a penis with the morphological features of the hyaena clitoris, and 'feminization' of females exaggerated the sex differences that are typical of this species. The effects of treatment were present at birth and persisted for at least 6 months. Treatment of pregnant females with flutamide and finasteride also markedly reduced circulating concentrations of testosterone and dihydrotestosterone in maternal plasma during pregnancy. Plasma delta 4-androstenedione was reduced in the female, but not the male, infants of treated mothers, consistent with an epigenetic hypothesis previously advanced to explain hormonal 'masculinization' of females. The present 'feminizing' effects of prenatal anti-androgen treatment are consistent with contemporary understanding of sexual differentiation, which accounts for morphological variation between the sexes in terms of steroids. However, current theory does not account for the basic genital structure of females and the present data suggest that development of the male penis and scrotum, and the female clitoris and pseudoscrotum, in spotted hyaenas may involve both androgen-dependent and androgen-independent components.

Urogenital and vasomotor symptoms in relation to menopausal status and the use of hormone replacement therapy (HRT) in healthy women during transition to menopause

OBJECTIVE

To investigate the relationship between climacteric status, hormonal levels, vasomotor symptoms, vaginal dryness and urinary incontinence in a cohort of healthy women during transition to menopause, and further to evaluate the effects of hormone replacement therapy on these symptoms.

METHODS

A total of 147 women were followed for 4 years during transition to menopause. They were all 49 years old when entering the study. Each annual visit included a general health screening, gynecological examination and blood sampling. The subjects were questioned about sociodemographic background, obstetric and gynecological history and they kept bleeding diary cards.

RESULTS

Urinary incontinence was reported by 57% at the first visit and decreased to 34% at the last visit. No correlation to hormonal levels or to the use of HRT (hormone replacement therapy) was seen, but parity was significantly (P = 0.05) correlated to urinary incontinence. Vaginal dryness occurred in 37% at the first visit. Vaginal dryness was experienced by 1/3 of the premenopausal women. Vasomotor symptoms were reported by 56% at the first visit and were associated with high levels of FSH and LH (P < 0.001 and P = 0.002, respectively). One third of premenopausal women reported on vasomotor symptoms. Hormone replacement therapy did not relieve hot flushes in these women.

CONCLUSIONS

Urogenital and vasomotor symptoms experienced by premenopausal women do not seem to be relieved by hormone replacement therapy.

Cadmium-induced apoptosis in the urogenital organs of the male rat and its suppression by chelation

Cadmium-induced apoptosis is shown to occur, in vivo, in several organs of the male Wistar rat urogenital system, 48 h after cadmium administration i.p. at a dose of 0.03 mmol/kg. Characteristic DNA fragmentation (as measured by an enzyme-linked immunosorbent-assay, ELISA) and histopathologically observed changes characteristic of apoptosis are found in the kidney, prostate, seminal vesicles, testes, and epididymis. TUNEL assay also demonstrates the apoptosis. Such changes are absent from bladder and vas deferens tissue. Timely administration of an appropriate chelating agent capable of reaching intracellular cadmium binding sites can suppress the processes leading to apoptosis. Administration of monoisomyl meso-2,3-dimercaptosuccinate (Mi-ADMS, 0.5 mmol/kg i.p.) to cadmium-treated rats is effective in greatly reducing typical histopathologic signs of apoptosis and the associated chromatin DNA fragmentation as revealed by ELISA when the antagonist is administered 1 h after cadmium. Administration of the chelating agent at law times results in greater degradation of DNA into oligonucleotides and more prominent histopathological evidence of apoptotic changes in the affected organs of the rat urogenital system. There is also a progressive increase in apoptotic changes indicated by TUNEL assay, as the antagonist is administered at progressively greater intervals after cadmium.

Urogenital aging: solutions in clinical practice

Urogenital aging, the most prevalent consequence of the menopause, affects at least 50% of postmenopausal women. It can lead to a lower quality of life, sexual problems, pain at intercourse/micturition and incontinence, but is yet an undertreated condition. The ideal treatment should relieve the vaginal symptoms of estrogen deficiency, have a localized effect, be convenient and easy to apply, safe to the endometrium and be without the unpleasant discharge produced by vaginal creams and pessaries. Vagifem, a new vaginal tablet containing 25 microg 17beta-estradiol, may fulfill many of the criteria required of an agent for the effective and efficient management of urogenital atrophy.

[Urogenital atrophy and recurrent urinary tract infection in elderly patients]

Postmenopausal lower urinary tract atrophy and its relations to recurrent urinary infections in elderly women are studied. Clinical aspects, functional and histological aspects and hypothetic mechanisms of atrophy are reported, epidemiologic data, mechanisms of urinary infections and of estrogen effects are reviewed and reports on the results of local or systemic use of drugs from the literature are presented. Local administration of estrogen seems to be efficient on the urinary tract. Local treatment is less dangerous and cheaper than systemic treatment. Hormonal treatment is one of the preventive measures against recurrent urinary infections in elderly women.

[Urogenital complaints: value of systemic estrogen therapy]

Local and systemic therapies with estrogens lead to a fast alleviation of urogenital symptoms, which occur frequently in the postmenopausal women. Especially atrophical changes in vulva and vagina, but also complaints about incontinence are improved by estrogen therapy. Even though there is no objective evidence of an improvement of stress incontinence, there are less infections of the lower urinary tract as well as a diminution of urge incontinence. Moreover, systemic estrogen therapy helps to prevent postmenopausal osteoporosis and cardiovascular diseases. Urogenital complaints may motivate patients easily for a long lasting systemic estrogen therapy, because symptoms are bothering and annoying.

[Topical hormonal treatment and urogenital atrophy]

Hypoestrogenemia-derived urogenital symptoms after menopause manifest after some years of hormonal deficit and appear commonly in elderly, untreated women. In the urogenital tract low postmenopausal estrogen levels lead to vaginal irritation and dryness and to dyspareunia, often accompanied by other symptoms like uriesthesis, incontinence or recurrent infections. Every systemic estrogen treatment is accepted as efficient for the correction of urogenital symptoms, often even at doses lower than those necessary for the correction of vasomotor symptoms. Diverse local treatments have been proposed: estriol, promestriene and low-dose estrone or estradiol. Promestriene applied locally stimulates differentiation and maturation of vaginal mucosa and compensates local hypoestrogenic effects without marked hormonal effects outside the vagina. Vaginal application of estrone, on the other hand, has rather been proposed for systemic hormone substitution and elevated levels of estrone and estradiol observed in the plasma render this method in-appropriate in cases where strictly local effects are desired. Recently, very low doses of estradiol in a range of 7.5 micrograms/day have been proposed for the treatment of urogenital atrophy by means of a prolonged release regimen. Among the described preparations, those with strictly local (devoid of systemic) effects should be restricted to patients with contraindications for systemic substitution therapy. Local estrogen therapies are recommended for the treatment of complaints due to vulvar and vaginal atrophy. They have also been proposed by certain authors for the acceleration of the cervico-vaginal and vulvar cicatrisation after surgical interventions or postpartum. The presence of miction disorders in elderly postmenopausal women is also a point in favour of local treatment.

Androgen metabolism in the prostate of the finasteride-treated, adult rat: a possible explanation for the differential action of testosterone and 5 alpha-dihydrotestosterone during development of the male urogenital tract

Previous work has clearly demonstrated that inhibition of 5 alpha-dihydrotestosterone (DHT) formation in vivo is not as effective as total androgen ablation (castration) in causing involution of the prostate. It is likely that this is due to the fact that testosterone is partially effective in maintaining androgen action. To provide insight into this observation, the androgenic metabolites of testosterone, androstenedione, and 5 alpha-DHT, were measured in prostate tissue and in blood of 5 alpha-reductase inhibitor (finasteride)-treated adult male rats. Finasteride treatment caused a significant decrease in prostatic DHT levels and a profound increase in prostatic testosterone and androstenedione levels. Similarly, circulating DHT levels were decreased in finasteride-treated rats (0.02 ng/ml compared with 0.05 ng/ml seen in control rats); and circulating androstenedione and testosterone levels were significantly elevated in finasteride-treated animals compared with controls. The in vitro effects of finasteride were assessed on the metabolism of [3H]testosterone in a tissue-slice assays. In the prostate, the inhibition of 5 alpha-reductase activity resulted not only in the decreased formation of 5 alpha-reduced metabolites (primarily DHT and 5 alpha-androstanedione), but also an increase in the 17-oxo metabolite androstenedione. In contrast, the tissues derived from the embryonic wolffian duct (seminal vesicle and epididymis) formed relatively low amounts of 17-keto steroids. Because DHT is a high affinity ligand for the androgen receptor and androstenedione shows very little, if any, affinity for the receptor, these studies suggest that 5 alpha-reduction of testosterone may be a mechanism to amplify androgen action in urogenital tissues such as the prostate by preventing catabolism of testosterone to the inactive androgen, androstenedione, at the site of hormone action.

Müllerian inhibiting substance inhibits branching morphogenesis and induces apoptosis in fetal rat lung

Müllerian inhibiting substance (MIS) is a glycoprotein hormone required for normal male reproductive tract development; it is presumed to signal through a heteromeric complex of type I and type II receptors. MIS exposure produces a paracrine-mediated regression of the embryonic Müllerian duct with histological changes consistent with apoptosis. MIS has also been shown to inhibit fetal lung development in vitro and in vivo, although the mechanism of this inhibition is unknown. The primordial lung and gonad are anatomically proximate on embryonic day 13.5, raising the possibility of a paracrine-mediated influence of MIS in male embryos on lung as well as MIS effecting dissolution of the Müllerian duct. We hypothesized that a negative regulatory event(s) might occur in the lung, as occurs in the duct, at the onset of MIS protein expression; thus, apoptosis and branching morphogenesis were studied in explanted fetal rat lungs incubated with proteolytically activated MIS. MIS exposure resulted in reduced total lung bud number as well as lung perimeter length. Explanted lungs exposed to MIS also exhibited numerous apoptotic bodies. To assess whether this MIS-induced phenomenon in lung might be mediated by the MIS type II receptor (MIS RII), reverse transcriptase-PCR performed on multiple fetal rat lung RNA samples using oligonucleotide primers designed from the 3'-untranslated region of rat MIS RII complementary DNA showed a product of the expected size that when sequenced was nearly identical to rat MIS RII. Northern blot analysis using polyadenylated fetal rat lung RNA and a 3'-MIS RII probe revealed a 2-kilobase transcript that was also seen in testicular messenger RNA. These studies show that the putative ligand binding receptor for MIS is expressed in embryonic lung, where MIS negatively modulates branching and activates apoptosis. We speculate that the mechanism of MIS-induced inhibition of lung development in the male fetus begins with MIS binding to the MIS RII, followed by a signaling cascade resulting in delayed airway branching temporally associated with enhanced apoptosis.

Comparative regulation of alpha1-adrenergic receptor mediated contraction in urogenitally derived smooth muscle. Effect of epidermal growth factor

Contractility of smooth muscle within mammalian urogenital organ systems has an established role in physiological/pathophysiological functioning of the component structures. Our aim was to examine the direct effect of epidermal growth factor (EGF) on smooth muscle tone as well as its indirect effects in regulating alpha1-adrenoceptor-mediated contraction of the prostate, the vas deferens and renal arteries. Tissues were mounted isometrically, under controlled conditions, and changes in tension in response to treatment with phenylephrine (PE) with or without pretreatment with EGF were recorded on a physiological recorder via force transducers. In the rabbit prostate, EGF potentiated the magnitude of contraction to PE. The potentiation appeared to be dependent on cyclo-oxygenase products. In the human prostate, EGF potentiated the contractile response to PE. EGF had no effect on the PE-induced contraction of the rabbit renal artery and vas deferens. EGF alone did not alter smooth muscle tone in any of the above-mentioned tissues. The main finding of this study is the difference in the regulation by EGF of the alpha1-adrenoceptor-mediated response in smooth muscle of the prostate, from that by the vas deferens and renal artery. The reasons for this difference in response remain to be elucidated. This study may form the basis for further investigation into receptor transregulation and its relevance to symptomatic benign prostatic hyperplasia (BPH).