Effect of castration on male rabbit lower urinary tract tissue enzymes

Updates on androgen replacement therapy and lower urinary tract symptoms: a narrative review

Lower urinary tract symptoms (LUTS) are caused by higher tension at the bladder neck level (due to fibrosis or stiffness) or benign prostatic hyperplasia, which causes static obstruction of the bladder outlet. Both forms cause a group of symptoms such as hesitancy, intermittency, weak stream, nocturia, urine frequency, and urgency. Additionally, LUTS (obstructive or irritative symptoms) are common in elderly men with hypogonadism, identified as the reduced testes capability in producing sex steroids and sperm, and are categorized as testosterone deficiency. Even though the mode of action (MoA) of testosterone therapy (TTh) on hypogonadal men needs more researched and understanding, the effectiveness of TTh in the development of male genital organs has been reported in several studies. This review shows the latest updates of TTh in LUTS including potential adverse effects, advantages, and disadvantages.

Androgen receptor in bladder cancer: A promising therapeutic target

There has been a significant progress in the treatment of metastatic urothelial carcinoma in the last few years with the advent of immunotherapy after a long gap of no drug approvals for over 4 decades. While immunotherapy with checkpoint inhibitors has revolutionized the treatment of urothelial carcinoma, unfortunately, only a minority of patients respond to immunotherapy. Treatment options for patients who do not respond and/or progress on immunotherapy are very limited and overall prognosis remains dismal in metastatic urothelial carcinoma. The first targeted therapy targeting the fibroblast growth factor receptor (FGFR) was recently approved for bladder cancer, but it is effective only in select patients harboring the FGFR2 and FGFR 3 mutations. Antibody drug conjugates like enfortumab vedotin have shown promising activity in clinical trials. Development of novel targeted therapies remains an area of investigation and an unmet need in bladder cancer. Exploitation of androgen receptor (AR) is a potential strategy for targeted drug development in bladder cancer. A significant proportion of urothelial carcinoma patients express AR irrespective of gender. AR signaling in urothelial carcinoma has been linked to progression through multiple mechanisms, including activation of human epidermal growth factor receptor-2 (EGFR or HER-2) signaling and epithelial to mesenchymal transition (EMT). Furthermore, AR is enriched in the luminal papillary mRNA subtype of urothelial carcinoma and also mediates resistance to cisplatin-based chemotherapy. Preclinical evidence suggests that AR inhibition can successfully inhibit urothelial carcinoma growth as monotherapy and is synergistic with cisplatin-based chemotherapy. We review the preclinical and clinical evidence supporting the putative role of AR signaling in urothelial carcinoma pathogenesis, progression and its role as a novel therapeutic target and future directions.

Impact of Testosterone Deficiency and Testosterone Therapy on Lower Urinary Tract Symptoms in Men with Metabolic Syndrome

Lower urinary tract function is modulated by neural, vascular and urethral and bladder structural elements. The pathophysiological mechanisms of lower urinary tract symptoms (LUTS) encompass prostate enlargement, alterations in urethra histological structure bladder fibrosis and alterations in pelvic neuronal and vascular networks, The complex pathophysiological relationship between testosterone (T) deficiency (TD) and the constellations LUTS, and metabolic dysfunction manifested in the metabolic syndrome (Met S) remains poorly understood. TD has emerged as one the potential targets by which Met S may contribute to the onset and development as well as worsening of LUTS. Because it has been recognized that treatment of men with Met S with T therapy ameliorates Met S components, it is postulated that T therapy may represent a therapeutic target in improving LUTS. Furthermore, the effect of TD on the prostate remains unclear, and often debatable. It is believed that T exclusively promotes prostate growth, however recent evidence has strongly contradicted this belief. The true relationship between benign prostatic hyperplasia, TD, and LUTS remains elusive and further research will be required to clarify the role of T in both benign prostatic hypertrophy (BPH) and LUTS as a whole. Although there is conflicting evidence about the benefits of T therapy in men with BPH and LUTS, the current body of literature supports the safety of using this therapy in men with enlarged prostate. As the population afflicted with obesity epidemic continues to age, the number of men suffering from Met S and LUTS together is expected to increase.

Role of the androgen receptor in urothelial cancer

Men have had a substantially higher risk of developing bladder cancer than women. This has prompted research on androgen-mediated androgen receptor (AR) signaling in urothelial cancer. Indeed, increasing preclinical evidence indicates that AR activation correlates with the promotion of urothelial carcinogenesis and tumor outgrowth. In this article, we summarize and discuss available data suggesting the involvement of androgens and the AR pathway in the development and progression of urothelial cancer. Although precise mechanisms for the functions of AR and related signals in urothelial cells remain far from being fully understood, current observations may offer effective chemopreventive and therapeutic approaches for urothelial cancer. Clinical application of various anti-AR therapies available for AR-dependent prostate cancer to urothelial cancer patients is thus anticipated.

Androgen Receptor Signaling in Bladder Cancer

Emerging preclinical findings have indicated that steroid hormone receptor signaling plays an important role in bladder cancer outgrowth. In particular, androgen-mediated androgen receptor signals have been shown to correlate with the promotion of tumor development and progression, which may clearly explain some sex-specific differences in bladder cancer. This review summarizes and discusses the available data, suggesting the involvement of androgens and/or the androgen receptor pathways in urothelial carcinogenesis as well as tumor growth. While the precise mechanisms of the functions of the androgen receptor in urothelial cells remain far from being fully understood, current evidence may offer chemopreventive or therapeutic options, using androgen deprivation therapy, in patients with bladder cancer.

Effect of short-term androgen deficiency on bladder contractility and urothelial mediator release

In men, testosterone levels decline by 1% per year after the age of 40. Reduced androgen levels may directly contribute to lower urinary tract symptoms and bladder dysfunction, although the mechanisms are unclear. This study examined the effect of low testosterone and testosterone replacement on key mechanisms involved in local bladder function. Intraluminal release of the mediators ATP and ACh in response to bladder distension was measured in whole bladders from rats 8 weeks following castration, whilst bladder contractility was assessed using isolated strips. Human urothelial cells were cultured under low, physiological and supra-physiological testosterone conditions for 24 h or 5 days, and stretch-induced release of ATP and ACh was measured. Phasic contractile activity of bladder strips, agonist-induced reponses to carbachol and isoprenaline and nerve-evoked contractions were unaffected by castration. The acetylcholinesterase inhibitor neostigmine significantly increased amplitude of phasic activity only in bladder strips following castration, and this was prevented by testosterone replacement. Intraluminal ACh release following bladder distension was significantly reduced following castration, whilst ATP release was unaffected. In contrast, stretch-induced ATP release from urothelial cells was significantly enhanced in low testosterone conditions, whilst ACh release was unaltered. Testosterone-replacement to physiological levels prevented these changes. Whilst androgen deficiency of 8 weeks does not directly affect contractility of bladder smooth muscle, urothelial mediator release is sensitive to changes in testosterone. These changes in mediator release may be an early effect of the decline in testosterone and could affect sensory pathways in the longer term, contributing to the urinary symptoms and bladder dysfunction seen in androgen-deficient men.

Relationship between serum testosterone and nocturia in men without benign prostate enlargement

Recent studies have focused on the relationship between nocturia and serum testosterone because testosterone is thought to be an important factor of prostate growth. However, it remains unclear whether altered serum concentrations of testosterone is associated with an increased risk of nocturia because patients who were taking diuretics or who had a large prostate, which may precipitate nocturia, were not excluded from most previous studies. We analyzed the clinical records of 596 non-benign prostatic enlargement (BPE) male patients to explore the relationship between serum total testosterone and nocturia. All patients were evaluated using a serum prostate-specific antigen (PSA) assay, measurement of serum total testosterone, transrectal ultrasonography, uroflowmetry, and a compilation of the International Prostate Symptom Score (IPSS) and International Index of Erectile Function (IIEF) questionnaires. Nocturia was defined as ≥2 nocturnal voiding episodes. The number of nocturia episodes was assessed using IPSS question 7. To evaluate the effect of serum testosterone on nocturia, multivariate regression analysis was performed including the covariates of age, IPSS, IIEF score, body mass index, PSA, prostate volume, and maximal urine flow rate. Based on multivariate linear analysis, serum testosterone level was not significantly associated with the severity of nocturia. However, with regard to the relationship between prevalence of nocturia and serum testosterone, prevalence of nocturia was significantly positively associated with age (OR = 1.048, p = 0.005), total IPSS (OR = 1.217, p < 0.001), and testosterone level (OR = 1.150, p = 0.041). Therefore, in men without an enlarged prostate, testosterone may play an opposing role in the etiology of nocturia.

Effect of testosterone therapy on the urinary bladder in experimental hypogonadism of rats

Testosterone (T) deficiency is prevalent particularly in elderly men and lead to physical and sexual morbidities. Although low levels of T are associated with low urinary tract symptoms, the correlation between T deficiency and bladder dysfunction is not clearly identified. The aim of this study was to investigate the effect of high dose testosterone replacement therapy (TRT) on the histological structure of the UB in castrated rats. Twenty-five adult male rats were divided into three groups: control, castrated and castrated + TRT. T was administrated in high dose (100 mg/kg) two intramuscular injections/week for 60 days. UB sections were prepared and stained with H&E, Masson's trichrome and immunohistochemical detection of Cytokeratin 20 (Ck20). All data were morphometrically and statistically analyzed. In castrated group, significant atrophy of the urothelium (P < 0.001) accompanied with widening of the corium were observed. The smooth muscle appeared thin with marked increase in the collagen fibers. On treating the castrated group with TRT, atypical Ck20 expression as well as significant increase in urothelial thickness (P < 0.05) and smooth muscle/collagen ratio (P < 0.001) were detected. In castrated rat model, high dose TRT has a positive effect on the UB smooth muscle rather than the urothelium which acquired atypical patterns.

Effects of supraphysiological testosterone treatment and orchiectomy on ischemia/reperfusion-induced bladder dysfunction in male rabbits

INTRODUCTION

The roles of testosterone and orchiectomy on male bladder subjected to ischemic/reperfusion (I/R) injuries received little attention. To fill this gap, the present study intended to examine testosterone and orchiectomy effects on male rabbits subjected to I/R damages.

AIM

To elucidate the effects of testosterone and orchiectomy on contractile response, bladder morphology, interstitial fibrosis, and oxidative stress in male rabbit bladder subjected to I/R surgery.

METHODS

Male New Zealand rabbits were distributed into five groups as follows: Group 1 received sham surgical procedure. In group 2, I/R surgery was performed. In group 3, testosterone (100 μg/kg/day) was intramuscularly injected prior to I/R surgery. In group 4, orchiectomy was performed prior to I/R surgery. In group 5, orchiectomy was performed with subsequent testosterone administration, followed by I/R surgery. All the rabbits were euthanized 7 days after I/R. Comparative studies were analyzed to elucidate the effects of testosterone and orchiectomy on bladder dysfunction subjected to I/R injuries.

MAIN OUTCOME MEASURES

Bladder contractile function was evaluated. Masson's trichrome staining and immunohistochemical studies were performed to evaluate bladder morphology and intramural nerve terminals. Western blotting was examined to investigate the expressions of fibrosis and oxidative stress markers.

RESULTS

I/R surgery significantly decreased bladder contractility in response to various stimulations with and without testosterone treatment. I/R damages decreased bladder nerve density with and without testosterone. The expressions of fibrosis and oxidative stress-related proteins were increased by I/R injuries with or without testosterone treatment. Testosterone depletion significantly decreased the expressions of transforming growth factor-β and fibronectin expressions after I/R injury. Supraphysiological testosterone treatment after orchiectomy greatly increased the expressions of these fibrosis proteins; however, orchiectomy alone ameliorated I/R injuries.

CONCLUSIONS

Testosterone treatment or orchiectomy affected I/R-induced bladder damages in male rabbits. Orchiectomy decreased the level of fibrosis and oxidative stress markers and increased neurofilament densities. Supraphysiological exogenous testosterone administration after orchiectomy further exacerbated such detrimental effects of I/R.

The role of the androgen receptor in the development and progression of bladder cancer

Men are at a higher risk of developing bladder cancer than women. Since bladder cancer cell lines and tissues were found to express the androgen receptor, efforts have been made to inspect whether androgen-mediated androgen receptor signals are implicated in bladder carcinogenesis as well as cancer progression. Mounting evidence supports the view that bladder cancer is a member of the endocrine-related tumors and may clearly explain the gender-specific difference in the incidence. However, the underlying mechanisms of how androgen receptor signals regulate bladder cancer growth are still far from fully characterized. Moreover, it remains controversial whether the androgen receptor pathway always plays a dominant role in bladder cancer progression. In this review, we summarize the available data on the involvement of androgen receptor signaling in bladder cancer. In particular, current evidence demonstrating the stimulatory effects of androgens on tumor progression or, more convincingly, tumorigenesis via the androgen receptor pathway may offer great potential for androgen deprivation as a therapeutic or chemopreventive option in patients with bladder cancer.

The promise of inhibition of smooth muscle tone as a treatment for erectile dysfunction: where are we now?

Ten years ago, the inhibition of Rho kinase by intracavernosal injection of Y-27632 was found to induce an erectile response. This effect did not require activation of nitric oxide-mediated signaling, introducing a novel target pathway for the treatment of erectile dysfunction (ED), with potential added benefit in cases where nitric oxide bioavailability is attenuated (and thus phosphodiesterase type 5 (PDE5) inhibitors are less efficacious). Rho-kinase antagonists are currently being developed and tested for a wide range of potential uses. The inhibition of this calcium-sensitizing pathway results in blood vessel relaxation. It is also possible that blockade of additional smooth muscle contractile signaling mechanisms may have the same effect. In this review, we conducted an extensive search of pertinent literature using PUBMED. We have outlined the various pathways involved in the maintenance of penile smooth muscle tone and discussed the current potential benefit for the pharmacological inhibition of these targets for the treatment of ED.

Effects of testosterone on the lower urinary tract go beyond the prostate: New insights, new treatment options

The traditional assumption that the prostate is an organ exquisitely sensitive to androgen action still holds true, but with lower-than-normal circulating levels of testosterone, all androgen receptors are saturated and a further increase in circulating levels of testosterone has no effect on the prostate (saturation model). Prostate disease (prostate cancer and benign prostatic hyperplasia, BPH) usually occur at an age when circulating levels of testosterone are declining, so it is unlikely that they are to be attributed to an excess of testosterone. The bother of BPH is presently subsumed under ‘pathology of the lower urinary tract’. Surprisingly, these structures have androgen receptors, and depend for their relaxation on nitric oxide, for which the mechanism, in turn, is aided by androgens. This explains why phosphodiesterase type-5 inhibitors also benefit erectile function and symptoms of the lower urinary tract. Normalisation of testosterone in hypogonadal men favours this action. During the development of the prostate, epithelium and mesenchyme are under the control of testicular androgens, and interact to form an organised secretory organ. Furthermore, many of the disease processes of the prostate have been attributed to androgen action, and consequently, therapies have been aimed at manipulating androgen activity.

Sarcoplasmic reticulum function in smooth muscle

The sarcoplasmic reticulum (SR) of smooth muscles presents many intriguing facets and questions concerning its roles, especially as these change with development, disease, and modulation of physiological activity. The SR's function was originally perceived to be synthetic and then that of a Ca store for the contractile proteins, acting as a Ca amplification mechanism as it does in striated muscles. Gradually, as investigators have struggled to find a convincing role for Ca-induced Ca release in many smooth muscles, a role in controlling excitability has emerged. This is the Ca spark/spontaneous transient outward current coupling mechanism which reduces excitability and limits contraction. Release of SR Ca occurs in response to inositol 1,4,5-trisphosphate, Ca, and nicotinic acid adenine dinucleotide phosphate, and depletion of SR Ca can initiate Ca entry, the mechanism of which is being investigated but seems to involve Stim and Orai as found in nonexcitable cells. The contribution of the elemental Ca signals from the SR, sparks and puffs, to global Ca signals, i.e., Ca waves and oscillations, is becoming clearer but is far from established. The dynamics of SR Ca release and uptake mechanisms are reviewed along with the control of luminal Ca. We review the growing list of the SR's functions that still includes Ca storage, contraction, and relaxation but has been expanded to encompass Ca homeostasis, generating local and global Ca signals, and contributing to cellular microdomains and signaling in other organelles, including mitochondria, lysosomes, and the nucleus. For an integrated approach, a review of aspects of the SR in health and disease and during development and aging are also included. While the sheer versatility of smooth muscle makes it foolish to have a "one model fits all" approach to this subject, we have tried to synthesize conclusions wherever possible.

Concurrent improvement of the metabolic syndrome and lower urinary tract symptoms upon normalisation of plasma testosterone levels in hypogonadal elderly men

Central obesity in adulthood, the metabolic syndrome, erectile failure and lower urinary tract symptoms (LUTS) are all associated with lower-than-normal testosterone levels, although the relationship between testosterone and LUTS appears weak. The metabolic syndrome is associated with an overactivity of the autonomic nervous system. Alternatively, the metabolic syndrome is associated with markers of inflammation, such as C-reactive protein (CRP), maybe signalling intraprostatic inflammation. A large cohort of 95 middle-aged to elderly hypogonadal men (T levels 5.9-12.1 nmol l(-1)) were treated with parenteral testosterone undecanoate and its effects on the metabolic syndrome {waist circumference, cholesterol, CRP and LUTS [residual bladder volume (RBV), International Prostate Symptoms Score (IPSS), prostate volume, prostate-specific antigen (PSA)]} were evaluated. Along with the improvements of the metabolic syndrome, there was a significant decline of the values of the IPSS, RBV and CRP. There was a (low) level of correlation between the decline of waist circumference and residual volume of urine but not with IPSS and prostate size. Along with the improvement of the metabolic syndrome upon testosterone administration, there was also an improvement of the IPSS and of RBV of urine and CRP. The mechanism remains to be elucidated.

Lower urinary-tract symptoms and testosterone in elderly men

Objectives

The objective was to examine the effects of testosterone administration on symptom scores of lower urinary tract symptoms (LUTS).

Methods

The literatures on the epidemiological association between the metabolic syndrome, erectile failure and (LUTS) were reviewed.

Results

In men with the metabolic syndrome and erectile failure, often lower-than-normal testosterone levels are found. This is less clear for men with LUTS, but the relationship between testosterone and LUTS might be indirect and based on the association of the metabolic syndrome with an overactivity of autonomic nervous system. This overactivity may play a key role in increasing the severity of LUTS above an intrinsic basal intensity that is determined by the genitourinary factors in aging men. Androgen receptors are present in the epithelium of the urethra and the bladder. Testosterone may play a role in the reflex activity of the autonomic nervous system in the pelvis, or may interact with postsynaptic non-genomic receptors suppressing detrusor activity. Human neurons in the wall of the bladder contain nitric oxide synthase. Similar to the penis, testosterone has an impact on nitric oxide synthase.

Conclusions

Some studies investigating the effects of normalizing testosterone levels in elderly men have found a positive effect on variables of the metabolic syndrome and, simultaneously, on scores of the International Prostate Symptoms Score (IPSS) which is worthy of further investigation in randomized, controlled and sufficiently powered clinical trials.

Lower urinary tract symptoms and its potential relation with late-onset hypogonadism

The study of the health status of the aging male takes presently a more integrative approach and it appears that ailments typical of male aging, such as lower urinary tract symptoms (LUTS), (visceral) obesity, metabolic syndrome and erectile failure are significantly interrelated. A common denominator of the above ailments is lower-than-normal testosterone levels occurring in a significant proportion of elderly men. This review addresses the potential connections between LUTS and late-onset hypogonadism. In animal studies there appear to be androgen and estrogen receptors in the urothelium and smooth muscle cells of the urethra and bladder of the rat and rabbit, as well as in the neurons in the autonomic ganglia of the prostatic plexus of the male rat. Upon castration electrically evoked relaxations of the smooth muscle of the prostatic urethra were decreased. There is a Rho-kinase activation/endothelin pathway; possibly involved in the increased smooth muscle activity found in both LUTS/benign prostate hyperplasia. Nitric oxide (NO) appears to have a smooth muscle relaxing effect in the urogenital organs. Studies in humans have convincingly shown that phosphodiestererase inhibitors have a beneficial effect on LUTS. More intervention studies should be undertaken to test the clinical validity of the theoretically plausible interrelationship between LUTS and late-onset hypogonadism.