Erectile function and nocturnal penile tumescence in patients with prostate cancer undergoing luteinizing hormone-releasing hormone agonist therapy

The Dutch Protocol for Juvenile Transsexuals: Origins and Evidence

It has been a quarter of a century since Dutch clinicians proposed puberty suppression as an intervention for "juvenile transsexuals," which became the international standard for treating gender dysphoria. This paper reviews the history of this intervention and scrutinizes the evidence adduced to support it. The intervention was justified by claims that it was reversible and that it was a tool for diagnosis, but these claims are increasingly implausible. The main evidence for the Dutch protocol came from a longitudinal study of 70 adolescents who had been subjected to puberty suppression followed by cross-sex hormones and surgery. Their outcomes shortly after surgery appeared positive, except for the one patient who died, but these findings rested on a small number of observations and incommensurable measures of gender dysphoria. A replication study conducted in Britain found no improvement. While some effects of puberty suppression have been carefully studied, such as on bone density, others have been ignored, like on sexual functioning.

Ethical issues arising in the provision of medical interventions for gender diverse children and adolescents

The care of children and adolescents whose experience of the body is at odds with their gender feelings raises a number of questions that are as much ethical as medical or psychological. In this article I highlight some areas of ethical concern from the point of view of a senior clinician at the nationally commissioned UK Gender Identity Development Service (GIDS). I make the assumption that ethical deliberation is relational and grounded in the natural, social, political and institutional worlds in which the ethical questions arise. I try to show how matters of empirical fact, alongside an appreciation of broad social contexts, and historic and current power relations, provide an essential framework for the ways that ethical choices are framed by key groups of people as they take up different, sometimes opposing, ethical positions. I argue that practising ethically in such a service is not helpfully reduced to a single event, a treatment decision aimed at achieving the morally 'right' outcome, but an extended process in time. In the charged debate surrounding the recognition of these young people's needs, we must do more to promote responsible debate about the scope of sound ethical practice.

Functional and structural changes in internal pudendal arteries underlie erectile dysfunction induced by androgen deprivation

Androgen deficiency is strongly associated with erectile dysfunction (ED). Inadequate penile arterial blood flow is one of the major causes of ED. The blood flow to the corpus cavernosum is mainly derived from the internal pudendal arteries (IPAs); however, no study has evaluated the effects of androgen deprivation on IPA's function. We hypothesized that castration impairs IPAs reactivity and structure, contributing to ED. In our study, Wistar male rats, 8-week-old, were castrated and studied 30 days after orchiectomy. Functional and structural properties of rat IPAs were determined using wire and pressure myograph systems, respectively. Protein expression was determined by Western blot and immunohistochemistry. Plasma testosterone levels were determined using the IMMULITE 1000 Immunoassay System. Castrated rats exhibited impaired erectile function, represented by decreased intracavernosal pressure/mean arterial pressure ratio. IPAs from castrated rats exhibited decreased phenylephrine- and electrical field stimulation (EFS)-induced contraction and decreased acetylcholine- and EFS-induced vasodilatation. IPAs from castrated rats exhibited decreased internal diameter, external diameter, thickness of the arterial wall, and cross-sectional area. Castration decreased nNOS and α-actin expression and increased collagen expression, p38 (Thr180/Tyr182) phosphorylation, as well as caspase 3 cleavage. In conclusion, androgen deficiency is associated with impairment of IPA reactivity and structure and increased apoptosis signaling markers. Our findings suggest that androgen deficiency-induced vascular dysfunction is an event involving hypotrophic vascular remodeling of IPAs.

Dutasteride-mediated morphological changes in the genitourinary tract associated with altered expression patterns of the androgen and estrogen receptors in male rats

We evaluated the effects of dutasteride on the genitourinary tract using fifteen 8-week-old male Sprague-Dawley rats. Animals were divided into three groups comprising five animals each and treated as follows. Group A was a control group, members of Group B received oral administration of dutasteride 0.1 mg/kg/day from the age of 8 to 16 weeks, and members of Group C were castrated at the age of 8 weeks. All rats were killed at the age of 16 weeks for the sample collection of blood, bladder, prostate, seminal vesicles, and penis. Then, we evaluated the pathological examination for evaluating the tissue fibrosis and hormonal receptor expression. The results showed that the mean size of the prostate and seminal vesicles was smaller in Group B and Group C than in Group A. Serum and tissue concentrations of both testosterone and dihydrotestosterone were remarkably reduced in serum and all tissues in Group C compared with Group A. On the other hand, in Group B, only dihydrotestosterone was reduced in serum and penis. Histopathological examination revealed that Group C showed statistically significant histological changes, such as an increase in fibrotic tissue in the bladder, prostate, and penis. Similarly, Group B showed fibrotic changes in the prostate and penis compared with the Group A. Immunofluorescent staining revealed that the androgen receptor was more strongly expressed than the estrogen receptor beta in Group A. On the other hand, in Group C, weak expression of the androgen receptor and strong expression of the estrogen receptor beta was noted. In Group B, these changes were noted in the prostate and penis. These findings suggest that dutasteride cause morphological changes not only in prostate but also in penis. These changes are associated with altered expression patterns of androgen receptor and estrogen receptor.

Animal models of erectile dysfunction

Erectile dysfunction (ED) is a prevalent male sexual dysfunction with profound adverse effects on the physical and the psychosocial health of men and, subsequently, on their partners. The expanded use of various types of rodent models has produced some advances in the study of ED, and neurophysiological studies using various animal models have provided important insights into human sexual dysfunction. At present, animal models play a key role in exploring and screening novel drugs designed to treat ED.

Role of androgens in modulating male and female sexual function

Advancement in basic and clinical research has provided considerable evidence suggesting a key role of androgens in the physiology and pathophysiology of sexual function. Evidence from clinical studies in men and women with androgen deficiency support a role of androgens in maintaining sexual function in men and women and are integral in maintaining sexual health. Preclinical studies utilizing male animal models demonstrated a role of androgens in maintenance of: (i) penile tissue structural integrity, (ii) penile trabecular smooth muscle growth and function, (iii) integrity of penile nerve fiber network, (iv) signaling pathways in the corpora cavernosa, (v) myogenic and adipogenic differentiation in the corpora cavernosa, (vi) physiological penile response to stimuli, and (vii) facilitating corporeal hemodynamics. These findings strongly suggest a role for androgen in the physiology of penile erection. In addition, clinical studies in hypogonadal men with erectile dysfunction treated with testosterone provided invaluable information on restoring erectile function and improving ejaculatory function. Similarly, clinical studies in surgically or naturally postmenopausal women with androgen deficiency suggested that androgens are important for maintaining sexual desire and testosterone treatment was shown to improve sexual desire, arousal and orgasm. Furthermore, studies in female animal models demonstrated that androgens maintain the integrity of vaginal nerve fiber network, muscularis volume, and enhance genital blood flow and mucification. Based on the biochemical, physiological and clinical findings from human and animal studies, we suggest that androgens are integral for maintaining sexual function and play a critical role in maintaining sexual health in men and women.

Development of UK guidance on the management of erectile dysfunction resulting from radical radiotherapy and androgen deprivation therapy for prostate cancer

AIM

To develop a management strategy (rehabilitation programme) for erectile dysfunction (ED) after radiotherapy (RT) or androgen deprivation therapy (ADT) for prostate cancer that is suitable for use in a UK NHS healthcare context.

METHODS

PubMed literature searches of ED management in this patient group together with a survey of 28 experts in the management of treatment-induced ED from across the UK were conducted.

RESULTS

Data from 19 articles and completed questionnaires were collated. The findings discussed in this article confirm that RT/ADT for prostate cancer can significantly impair erectile function. While many men achieve erections through PDE5-I use, others need combined management incorporating exercise and lifestyle modifications, psychosexual counselling and other erectile aids. This article offers a comprehensive treatment algorithm to manage patients with ED associated with RT/ADT.

CONCLUSION

Based on published research literature and survey analysis, recommendations are proposed for the standardisation of management strategies employed for ED after RT/ADT. In addition to implementing the algorithm, understanding the rationale for the type and timing of ED management strategies is crucial for clinicians, men and their partners.

Impact of androgen deprivation therapy on sexual function

Many patients with prostate cancer for whom androgen deprivation therapy (ADT) is indicated are young and desire to remain sexually active. In such patients, the side effects of androgen therapy on sexual function can be a source of serious reduction in overall quality of life. Providing the appropriate treatment options in this patient population is therefore essential. Nevertheless, treating such patients is challenging and an understanding of the underlying mechanisms of sexual physiology and pathophysiology is crucial to optimal patient care. In this paper, we reviewed what was known regarding the effects of ADT on sexual function in animal models and we also provided a detailed review on the effects of ADT on sexual health in humans and its treatment.

Role of estrogen in normal male function: clinical implications for patients with prostate cancer on androgen deprivation therapy

PURPOSE

Patients with prostate cancer on androgen deprivation therapy with luteinizing hormone-releasing hormone agonists experience deleterious side effects, including sexual dysfunction, hot flashes and osteoporosis. Estrogen may relieve or reduce some of these side effects. We explore the role of estrogen in normal male function, emphasizing sexual interest and performance.

MATERIALS AND METHODS

We reviewed the literature on androgen deprivation therapy, estrogen and sexual function in males using PubMed® and other sources.

RESULTS

Estrogen receptors are present in tissues involved in sexual behavior including several brain centers and pelvic floor muscles. Exogenous estrogens can restore some sexual interest to greater than castrate level in castrated animals. This has also been reported for certain androgen deprived patients (eg voluntarily castrated men, male-to-female transsexuals) who take exogenous estrogens and others who are on high dose antiandrogens which increase endogenous estradiol levels. Estrogen also helps prevent hot flashes and bone mineral loss, which commonly occur with luteinizing hormone-releasing hormone agonist treatment. However, estrogen may cause gynecomastia and increases the risk of breast cancer. Thus, patients with prostate cancer should be informed about the pros and cons of estrogen therapy before starting androgen deprivation therapy. Based on these data estrogen is likely to have maximal benefits in men if initiated simultaneously with androgen deprivation therapy. Because estrogen autoregulates its own receptors, a constant dose of estrogen will not likely produce a constant serum concentration, suggesting that its effectiveness could be optimized if administered cyclically.

CONCLUSIONS

Prospective studies on the ability of parenteral estrogen to preserve sexual interest at greater than castrate level in patients with prostate cancer are warranted.

Management of complications of androgen deprivation therapy in the older man

Prostate cancer is the most common malignancy in older men. With the aging of the population, the number of older men with prostate cancer will grow rapidly. Androgen deprivation therapy (ADT) is the mainstay of treatment for men with systemic disease and is increasingly utilized as primary therapy or in combination with other therapies for localized disease. Side effects of therapy are multifold and include hot flashes, osteoporosis, and adverse psychological and metabolic effects. Recent research has illustrated that ADT can negatively impact the functional, cognitive, and physical performance of older men. Patients with prostate cancer, despite recurrence of the disease, have a long life expectancy and may be subjected to the side effects of ADT for many years. This review highlights the complications of ADT and approaches to management. We also provide recommendations for assessment and management of ADT complications among the most vulnerable and frail older male patients.

The treatment of sleep-related painful erections

INTRODUCTION

As specialists in male genital problems, urologists and sexologists will most likely to be involved in the treatment of males presenting with sleep-related painful erections (SRPEs). This means that this phenomenon needs to be recognized by urologists and sexologists, and that they should have knowledge of the current diagnostic and therapeutic approaches. Aim. To review the literature on SRPE and to find the best pharmacological treatment. Methods. Four personal clinical observations from two clinics and 29 other cases with SRPE found in PubMed were analyzed, especially regarding the results of pharmacological treatment.

MAIN OUTCOME MEASURES

The results of pharmacological treatment.

RESULTS

Many of the various treatments proved to be ineffective and only a few showed efficacy for a few weeks or months. The only effective drugs in the long term were baclofen, clonazepam, and clozapine.

CONCLUSIONS

Until now, the phenomenon of SRPE is not well understood. The rarity of the published cases undoubtedly does not reflect the actual occurrence of SRPE. Controlled double-blind pharmacological trials are needed, and long-term follow-up including polysomnography coupled with nocturnal penile tumescence and rigidity monitoring may provide further information about SRPE.

REVIEWS: Are Androgens Critical for Penile Erections in Humans? Examining the Clinical and Preclinical Evidence

Androgens are deemed critical for penile-tissue development, growth, and maintenance of erectile function, however, their role in erection, especially in humans, remains controversial. In this review, we summarize information from clinical and animal model studies to provide a comprehensive and rational argument for the role of androgens, or lack thereof, on penile erection ability in humans. The goal of this review is to present the clinical and preclinical evidence available in the literature with regard to testosterone and erectile physiology and engage the reader in this discussion. Ultimately, each reader will have to form his or her own conclusions based on the existing evidence. In humans, androgen-deficiency manifestations are noted in clinical situations such as: (i) inadequate development of the penis; and (ii) loss of erectile function in prostate cancer and benign prostatic hyperplasia patients managed with medical or surgical castration or antiandrogen therapy. Androgen treatment causes: (i) improvement in sexual function in hypogonadal patients treated with androgen supplementation; (ii) improvement in nocturnal penile tumescence in hypogonadal patients treated with androgens; (iii) improvement in erectile function with androgen supplementation in patients who did not respond to phosphodiesterase type 5 inhibitor therapy initially; and (iv) improvement in the well-being, mood, energy, and sexual function in aging men who have testosterone deficiency treated with androgen therapy. In contrast to animals, especially rodents in which the adrenal cortex does not synthesize androgens, the human adrenal is a source of peripherally circulating androgen precursors, thus, complete androgen insufficiency may not be observed in men at a younger age. Furthermore, in light of the concept that a threshold of androgen levels exists in animals and humans below which sexual function is diminished, further contributes to the complexity of understanding androgens role in erections, especially in humans. Nevertheless, based on the preclinical and clinical data available in the literature, to date, we infer that androgens play a critical role in maintaining erectile physiology in humans.

ORIGINAL RESEARCH—ENDOCRINOLOGY: The Physiological Role of Androgens in Penile Erection: Regulation of Corpus Cavernosum Structure and Function

It is generally accepted that androgens are critical for development, growth, and maintenance of penile erectile tissue. However, their role in erectile function, especially in humans, remains controversial. Clinical and preclinical studies have suggested that venoocclusion is modulated by the tone of the vascular smooth muscle of the resistance arteries and the cavernosal tissue and a balance between trabecular smooth muscle content and connective tissue matrix. In men with erectile dysfunction, venous leakage is thought to be a common condition among nonresponders to medical management and is attributed to penile smooth muscle atrophy. In the animal model, androgen deprivation produces penile tissue atrophy concomitant with alterations in dorsal nerve structure, endothelial morphology, reduction in trabecular smooth muscle content, and increased deposition of extracellular matrix. Further, androgen deprivation results in accumulation of fat-containing cells (adipocytes) in the subtunical region of the corpus cavernosum. Androgen deficiency diminishes protein expression and enzymatic activity of nitric oxide synthases (eNOS and nNOS) and phosphodiesterase type 5 (PDE5). The androgen-dependent loss of erectile response is restored by androgen administration but not by administration of PDE5 inhibitors alone. These data suggest that androgens regulate trabecular smooth muscle growth and connective tissue protein synthesis in the corpus cavernosum. Further, androgens may stimulate differentiation of progenitor cells into smooth muscle cells and inhibit their differentiation into adipocytes. Thus, we conclude that androgens exert a direct effect on penile tissue to maintain erectile function and that androgen-deficiency produces a metabolic and structural imbalance in the corpus cavernosum, resulting in venous leakage and erectile dysfunction. .

Testosterone and Sleep‐Related Erections: An Overview*

Sleep-related erections have been reported to occur from the intrauterine life to senescence. It has been speculated that the main function of nocturnal erections is to provide adequate engorgement of the corpora cavernosa, which then leads to increased tissue oxygenation. This is in turn to prevent cavernous fibrosis, the histopathological basis for corporeal venoocclusive dysfunction, which probably is the most common cause of organic erectile dysfunction. It has been suggested that sleep-related erections are triggered by the release of nitric oxide by the nitrergic nerve fibers within the cavernous nerves. Androgens regulate this mechanism as well as some other non-nitrergic processes within the corpora cavernosa and within the central nervous system. By contrast, the erectile response to tactile or visual erotic stimuli in wakefulness predominantly involves an androgen-independent system, although it may, at least to a certain degree, also be influenced by androgen-sensitive mechanisms. No doubt, androgens are key players in the physiology of nocturnal erections, and the availability of new, user-friendly testosterone preparations such as transdermal gel and intramuscularly administered testosterone undecanoate stimulates further investigations on this field. The prospect that the quality of sleep may also be improved by an androgen therapy administered to improve sleep-related erections in hypogonadal men needs further basic research and appropriate clinical studies.

Weapons of penile smooth muscle destruction: androgen deficiency promotes accumulation of adipocytes in the corpus cavernosum

In men with erectile dysfunction, venous leakage is a common condition among non-responders to medical management and is attributed to penile smooth muscle atrophy. Androgens play a role in regulating trabecular smooth muscle growth and function. Further, androgens stimulate differentiation of progenitor cells into smooth muscle cells and inhibit their differentiation into adipocytes. We postulate that androgens exert a direct effect on penile tissue to maintain erectile function, and that androgen deficiency produces metabolic and structural imbalances in the corpus cavernosum, resulting in venous leakage and erectile dysfunction. To date, research efforts on the mechanisms by which androgens regulate penile erectile physiology have mainly focused on investigating the role of the NO/cGMP pathway. However, androgen-dependent mechanisms that regulate tissue remodeling have been poorly defined. Characterization of the molecular and cellular mechanisms by which androgens regulate corpus cavernosum structural and functional integrity would provide significant gains in knowledge and understanding of an important pathogenic process. In this review, we discuss the potential role of androgen in maintaining differentiation of progenitor cells into smooth muscle lineage and inhibition of differentiation into adipocytes. Androgen deficiency promotes differentiation into adipogenic lineage, and accumulation of adipocytes in the corpus cavernosum may contribute to erectile dysfunction.

Adipocyte accumulation in penile corpus cavernosum of the orchiectomized rabbit: a potential mechanism for veno-occlusive dysfunction in androgen deficiency

Androgens are deemed to be critical for the development, growth, and maintenance of penile tissue as well as for erectile function. Androgens are also reported to inhibit differentiation of stroma progenitor cells into adipocytes and promote differentiation into smooth muscle. The objective of this study was to investigate whether androgen deprivation results in accumulation of adipocytes in the corpus cavernosum. Mature, New Zealand white male rabbits were subjected to sham surgery (control) or orchiectomy. Two weeks after surgery, erectile function was assessed by monitoring changes in intracavernosal blood pressure (ICP) in response to pelvic nerve stimulation. All ICP measurements were normalized to the mean systemic arterial blood pressure. In parallel studies, penile cross sections from control and orchiectomized rabbits were fixed and stained with either Masson's trichrome or hematoxylin and eosin to assess smooth muscle and connective tissue content. Alternatively, tissue sections were stained with Toluidine blue to assess accumulation of fat-containing cells. Orchiectomy resulted in loss of erectile function and penile atrophy, associated with reduced trabecular smooth muscle and increased connective tissue content. Most strikingly, tissue from orchiectomized animals exhibited accumulation of fat-containing cells (adipocytes) in the subtunical region of the corpus cavernosum. We hypothesize that androgen deprivation promotes differentiation of progenitor stroma cells into an adipogenic lineage producing fat-containing cells, thus altering erectile function.

Preventing and treating the complications of hormone therapy

Hormonal manipulation in the form of androgen-deprivation therapy for prostate cancer was introduced by Huggins and Hodges in 1941 and resulted in a Nobel Prize in 1966. Hormonal therapy initially had been used in metastatic prostate cancer, but the indications have been expanded including failed local therapy, locally advanced prostate cancer, and neoadjuvant or adjuvant therapy in high-risk localized prostate cancer. In view of the magnitude of the problem of prostate cancer and relatively frequent use of hormonal manipulation, it is important for clinicians to be aware of common side effects, prevention, and treatment to improve quality of life and reduce morbidity and mortality in patients with prostate cancer. This review focuses on the common side effects of hormonal treatment such as osteoporosis, anemia, hot flashes, erectile dysfunction, muscle wasting, gynecomastia, decline in cognitive function, depression, increase in body fat and metabolic changes, and their prevention and treatment.

Causes of erectile dysfunction

Erectile dysfunction (ED) arises as a result of a collision of circumstances among any of a number of factors (e.g., risk factors, causes, probable associations), each with its own primary power to affect the outcome. Furthermore, each of the components has its own timing as part of a complex effort of compensation and adjustment that often obscures the individual details. In the end, ED results from a failure of local tissues or systemic supply and control structures. The power of any individual "cause" to degrade erectile function is an important but as-yet unquantified property. The power of a small abnormality over a long or critical period (e.g., organogenesis), or many small contributions, or multiple risk factors will certainly be greater than the sum of the individual elements. Without a full quantitation of pathways and their potential influence, one can compare the importance of causative factors only in limited ways. Not surprisingly, it is the presence of a multiplicity of unidentified or poorly understood causative factors that accounts in large measure for the current inability to cure and prevent ED. There are two other important properties of a putatively causative factor for ED--reversibility and preventability--and these are strongly influenced by the time of onset and the duration of impact. Thus, a critical understanding that comes from recognizing the importance of the temporal associations of component factors is that the causes of ED in an individual may be guessed at but cannot be fully disclosed by an analysis of a "snapshot" of the disease taken at the time of diagnosis.

Andropause: Symptom Management for Prostate Cancer Patients Treated With Hormonal Ablation

Andropause, or the age-related decline in serum testosterone, has become a popular topic in the medical literature over the past several years. Andropause includes a constellation of symptoms related to lack of androgens, including diminished libido, decreased generalized feeling of well-being, osteoporosis, and a host of other symptoms. The andropause syndrome is very prominent in men undergoing hormonal ablation therapy for prostate cancer. Most significant in this population are the side effects of hot flashes, anemia, gynecomastia, depression, cognitive decline, sarcopenia, a decreased overall quality of life, sexual dysfunction, and osteoporosis with subsequent bone fractures. The concept of andropause in prostate cancer patients is poorly represented in the literature. In this article, we review the current literature on the symptoms, signs, and possible therapies available to men who cannot take replacement testosterone.

Is Bicalutamide Equivalent to Goserelin for Prostate Volume Reduction before Radiation Therapy? A Prospective, Observational Study

INTRODUCTION

We compare the cytoreductive efficacy of bicalutamide or goserelin with no hormonal manipulation in prostate cancer before brachytherapy.

MATERIALS AND METHODS

Transrectal ultrasound volume estimations were performed in clinic and during the brachytherapy-planning scan. Between volume estimations, patients received no hormonal treatment, bicalutamide 150 mg once daily or goserelin 3.6 mg every 28 days.

RESULTS

Patients receiving no hormonal manipulation had a volume increase of 8% compared with an 8% volume reduction in the bicalutamide group and a 26% reduction in the goserelin group. As initial prostate volume was not equivalent in the three groups, a subgroup analysis was performed on patients who received active treatment for more than 3 months who had initial prostate volume less than 55 cm3. In this subgroup, a mean fall in prostate volume of 7%, occurred in the bicalutamide group compared with 21% in the goserelin group. In both the original and subgroup analysis, the cytoreductive efficacy of goserelin was significantly greater than bicalutamide (P < 0.0001).

CONCLUSION

In the absence of data from randomised trials, comparing the efficacy of these agents, luteinising hormone-releasing hormone (LHRH) analogues remain the gold standard for cytoreduction before prostate brachytherapy. If the neoadjuvant efficacy of hormonal manipulation in external beam radiotherapy is dependent on prostate volume reduction, then LHRH analogues may also prove more effective in this neoadjuvant role.

Effects of medical or surgical castration on erectile function in an animal model

The goal of this study was to investigate the effects of medical castration (luteinizing hormone-receptor hormone [LH-RH] agonist treatment) or surgical castration on erectile function in an animal model. New Zealand White male rabbits were either kept intact (control); surgically orchiectomized; or treated for 2, 4, or 8 weeks with the LH-RH agonist leuprolide acetate (107 microg/kg/mo). At 2 weeks, plasma testosterone levels of orchiectomized and leuprolide acetate-treated animals were 12.8% and 57.4% of intact control animals, respectively. Erectile function was assessed by continuously recording systemic arterial pressure (SAP) and intracavernosal blood pressure (ICP) and determining the ICP:SAP ratios in response to electrical stimulation of the pelvic nerve at varying frequencies (2.5-32 Hz). Androgen deprivation by surgical (orchiectomy) or medical (leuprolide acetate) castration reduced ICP at all frequencies tested but did not alter SAP. Administration of the phosphodiesterase type 5 inhibitor vardenafil (10 microg/kg) did not enhance ICP in surgically orchiectomized or leuprolide acetate-treated animals. Nitric oxide synthase and arginase activities in the corpus cavernosum were not significantly altered by surgical or medical castration. Further, Masson trichrome staining of erectile tissue from androgen-ablated animals showed a reduction in smooth muscle content. These data demonstrate that androgen deprivation achieved by surgical or medical castration adversely affects penile hemodynamics and erectile function without producing significant changes in the activities of nitric oxide synthase or arginase. We conclude that androgen deprivation produces structural alterations in the corpus cavernosum leading to corporal veno-occlusive dysfunction.