Correlation of altered penile ultrastructure with clinical arterial evaluation

Update on corpus cavernosum smooth muscle contractile pathways in erectile function: a role for testosterone?

INTRODUCTION

Normal erectile function (EF) involves a coordinated relaxation of the arteries that supply the penis and the corpus cavernosum smooth muscle (CCSM), resulting in expansion of the sinusoids and increased intracavernous pressure. But the CCSM spends the majority of its time in the contracted state which is mediated by norepinephrine released from nerve endings and other vasoconstrictors like endothelins released from the endothelium. These agents cause smooth muscle myosin (SMM) phosphorylation by elevating intracellular calcium. When calcium returns to basal levels, the calcium sensitivity increases and prevents myosin dephosphorylation, which involves the RhoA/Rho-kinase (ROK) mechanism, thus maintaining force. Although mounting evidences demonstrate that androgens have a major influence on EF that is not just centrally mediated, this notion remains quite controversial.

AIM

To summarize the current knowledge on CCSM contractile pathways, the role they play in modulating EF, and the influence of androgens.

METHODS

The article reviews the literature and contains some previously unpublished data on CCSM contraction signaling including the role that androgens are known to play in modulating these pathways.

MAIN OUTCOME MEASURES

Data from peer-reviewed publications and previously unpublished observations.

RESULTS

In addition to downregulation of many pro-erectile molecular mechanisms, decreased testosterone (T) levels upregulate CCSM contractility, including hyperresponsiveness to α-adrenergic agonists, increased SMM phosphorylation, alteration of SMM isoform composition, activation of RhoA/ROK signaling and modulation of sphingosine-1-phosphate regulation of CCSM tone.

CONCLUSIONS

Decreased T levels upregulate CCSM contractile signaling. Meanwhile, it downregulates CCSM relaxation pathways synergizing to produce erectile dysfunction (ED). Although some urologists and researchers are still skeptical of the influence of androgens on penile erection, understanding these molecular control mechanisms as well as the influence that androgens have on these pathways should provide new evidence supporting the roles of androgens in EF and enhance the discovery of novel targets for drug development to treat ED.

A method to improve cellular content for corporal tissue engineering

We have previously shown that penile corporal structures engineered using autologous cells are able to achieve erection, penetration, and ejaculation. However, fully functional corpora could not be engineered because of the limited cellular content present within the corporal tissue construct. In this study, we investigated whether a dynamic seeding approach would improve cellularity within the corporal tissue construct and thereby restore normal erectile function. Corporal cells were either statically or dynamically seeded on acellular corporal tissue matrices and maintained in a bioreactor system. After 48 h, the cell-matrix complexes were implanted subcutaneously in athymic mice and analyzed for cell attachment, survival, and distribution using histological and molecular techniques. Native tissues and matrices without cells served as controls. The seeded cells attached and proliferated within the sinusoidal walls of the matrices. After completing the seeding, the DNA and cellular content of the dynamically seeded matrices reached 71% of normal corpora, whereas the statically seeded matrices reached 39% of normal corpora. These findings were confirmed histologically, biochemically, and using scanning electron microscopy. This study demonstrates that dynamic cell attachment, using a bioreactor system, leads to the formation of morphologically and biochemically improved corporal tissue, which may be useful for penile reconstruction.

Apoptosis of corpus cavernosum in patients with organic erectile dysfunction

OBJECTIVES

It has been reported that apoptosis of penile erectile tissue occurs after penile denervation, castration, and diabetes mellitus in animal studies. Aim of this study was to investigate apoptosis in corpora cavernosa of patients with organic erectile dysfunction (ED).

METHODS

Cavernous biopsies were obtained from 38 patients with erectile dysfunction and 10 patients with normal erectile function. Apoptosis of tissues were determined via terminal deoxyuridine nucleotide end labeling method by using flow cytometry.

RESULTS

The mean ages of patients with ED and control patients were 50.65 +/- 2.27, and 32.43 +/- 2.90 years, respectively (P = 0.0001). Patients with ED were set in two groups as more than 50 years old and less than 50 years old for further analysis of age factor on apoptosis. The mean % apoptosis of ED patients was 26.22 +/- 2.79 and control group was 11.26 +/- 3.79, (P = 0.032). Mean fluorescence intensity (MFI) values were also 17.41 +/- 3.21 and 6.59 +/- 2.28, respectively (P = 0.039). MFI and % apoptosis values were not statistically significant different neither between the patients groups nor between the control and patients < or = 50 years old (P > 0.05).

CONCLUSIONS

We did not find any statistically significant difference with respect to apoptosis rates when we compared neither control group with < or = 50 years old patients nor patients groups of ED. Because of this we did not have enough data to say that apoptosis has a prominent role on the development of ED independently from other factors. However, further studies are necessary to clarify the role of apoptosis in erectile dysfunction.

Biomechanics of male erectile function

Two major branches of engineering mechanics are fluid mechanics and structural mechanics, with many practical problems involving the effect of the first on the second. An example is the design of an aircraft's wings to bend within reasonable limits without breaking under the action of lift forces exerted by the air flowing over them; another is the maintenance of the structural integrity of a dam designed to hold back a water reservoir which would exert very large forces on it. Similarly, fluid and structural mechanics are involved in the engineering analysis of erectile function: it is the hydraulic action of increased blood flow into the corpora cavernosa that creates the structural rigidity necessary to prevent collapse of the penile column.

Early penile rehabilitation following radical prostatectomy: Cleveland clinic experience

Erectile dysfunction is one of the most important quality of life issues following radical prostatectomy. The potency rates reported following nerve-sparing technique varies between 40 and 86%, and the time period required for complete recovery of erectile function varies from 6 to 24 months. The literature evidence suggests that lack of natural erections during this period of time produces cavernosal hypoxia. Prolonged periods of cavernosal hypoxia induce fibrosis, which later increases the incidence of venous leak. Recently, there is a growing interest among the physicians to interrupt these events by preventing cavernosal hypoxia during the period of neuropraxia. Initial studies using intracavernosal injection appears to be beneficial. In this article, we reviewed the pathophysiology of cavernosal hypoxia following radical prostatectomy with currently available evidence for the interventions to promote the nerve recovery and regeneration.

A three-dimensional theoretical model of the relationship between cavernosal expandability and percent cavernosal smooth muscle

INTRODUCTION

Percent corporal smooth muscle content, a traditional predictor of corporal veno-occlusive function, is invasive and clinically assessed by histomorphometric analyses of erectile tissue biopsies. Cavernosal "expandability" which may be a more physiologically relevant parameter is a measure of work performed to achieve penile erection, and as a consequence, an indicator of the ability to approach maximum penile volume at low intracavernosal pressure.

AIM

To demonstrate that cavernosal "expandability" determined by noninvasive methodology can replace the determination of percent smooth muscle. To predict Young's modulus for the corpora cavernosa in rabbits and, this by inference, in humans; the latter facilitates the comparison of resistance to penile expansion presented by the tunica vs. cavernosal tissue.

MAIN OUTCOME MEASURE

A refined three-dimensional formula for cavernosal expandability, defined as the negative reciprocal of the cavernosal bulk modulus in the semierect state, was derived as a function of percent corporal smooth muscle content, using principles of engineering mechanics of materials. The model included Young's modulus, E, for the corpora cavernosa as an unknown parameter.

METHODS

Volume-pressure data obtained from three groups of New Zealand white rabbits: (i) control group (N = 7); (ii) hypercholesterolemic group (N = 5) on 0.5%; (iii) atherosclerotic group (N = 8), was plotted, and compared with the model.

RESULTS

Data points of mean cavernosal expandability (0.012-0.017 (mm Hg)(-1)) vs. percent trabecular smooth muscle content (33.9-45.4%) for the three groups of rabbits were analyzed. The revised model formula was fitted to the existing rabbit experimental data points producing a value of Young's modulus equal to 0.01 (MPa).

CONCLUSIONS

Rabbit cavernosal expandability can predict percent smooth muscle content. Cavernosal Young's modulus can be predicted. Further clinical research efforts to provide human data are needed.

Corpus Cavernosum Electromyography with Revised Methodology: An Explorative Study in Patients with Erectile Dysfunction and Men with Reported Normal Erectile Function

INTRODUCTION

A lack of standardization of the recording techniques of corpus cavernosum electromyography (CC-EMG) and objective criteria to characterize the recorded signals (CC-potentials) are the main difficulties hindering the clinical application of this method. These difficulties have been recently overcome by revising the recording and interpretation methodology of CC-EMG AIM: To assess if CC-EMG performed with the revised methodology is discriminative for well-defined clinical conditions in patients with erectile dysfunction (ED).

METHODS

Based on blinded clinical diagnosis, ED patients were catalogued into five subgroups: severe penile fibrosis, cavernous arterial insufficiency (CAI), cardio-vascular comorbidity (CVCM) without proven CAI, post-radical retropubic prostatectomy (RRP), and psychogenic ED. With four electrodes placed on the penile shaft bilaterally, CC-EMG was recorded monopolarly for 30 minutes during flaccidity. After evaluation of the recordings by visual inspection, CC-potentials were analyzed using cross- and autocorrelation techniques. The parameters evaluated were amplitude, duration, dominant frequency (DF), and maximum cross-correlation coefficient (Rmax) of CC-potentials recorded from proximal and distal parts of the CC.

MAIN OUTCOME MEASURES

Comparison of the values of parameters amplitude, duration, DF, and Rmax between patient and control groups.

RESULTS

A total of 119 patients with ED and 43 men with reported normal erectile function were studied. Thirteen out of 14 patients with severe penile fibrosis did not show any distinguishable CC-potential. Patients with CAI had significantly decreased amplitude compared with the potent controls, as well as the patients with CVCM but without proven CAI. Significantly decreased amplitude and Rmax were detected in ED patients following RRP compared with the controls.

CONCLUSIONS

Corpus cavernosum electromyography performed with the revised methodology is able to discriminate ED patients with conditions that are associated with cavernous smooth muscle degeneration and/or autonomic neuropathy from men with reported normal erectile function.

Management of the cardinal features of andropause

There are several problems facing aging men, especially sexual dysfunction, hypogonadism, and psychologic changes. This constellation of changes is sometimes referred to as "manopause" or "andropause." Unlike the dramatic changes in the hormonal milieu occurring during menopause in women, the age-related changes in reproductive hormones of men are subtle and occur gradually throughout the years of mature life. It has been estimated that circulating testosterone (T) declines longitudinally from age 19 at an average rate of 1% per year. The free or dialyzable fraction of serum T and the bioavailable (the sum of free fraction and loosely bound to albumin fraction) T decline more rapidly with age. Although the essential role of androgens in reproductive tissue development and emergence of secondary sex characteristics is well known, their role in adult sexual function seems to be primarily facultative. The effect of T on the central nervous system extends beyond sexual behavior. T has been shown to alter mood, memory, ability to concentrate, and the overall sense of vigor and well being that may interact with a host of other psychologic changes associated with aging. Disordered erectile function is not generally an endocrine problem but rather vascular, neurologic, and psychogenic in origin. It also may be the first sign of systemic vascular disease. The clinical management of andropause requires an individualized approach. In some men, the main problem may be psychologic, whereas in others, hypogonadism may play an important role. Many with erectile failure, suffer silently regardless of its etiology. In this review, we suggest some practical guidelines for the management of these conditions.

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.

Physiology of penile erection and pathophysiology of erectile dysfunction

This article reviews the physiology of penile erection, the components of erectile function, and the pathophysiology of erectile dysfunction. The molecular and clinical under-standing of erectile function continues to gain ground at a particularly fast rate. Advances in gene discovery have aided greatly in working knowledge of smooth muscle relaxation/contraction pathways. The understanding of the nitric oxide pathway has aided not only in the molecular understanding of the tumescence but also greatly in the therapy of erectile dysfunction.

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. .

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.

Microarray analysis reveals novel gene expression changes associated with erectile dysfunction in diabetic rats

To investigate the full range of molecular changes associated with erectile dysfunction (ED) in Type 1 diabetes, we examined alterations in penile gene expression in streptozotocin-induced diabetic rats and littermate controls. With the use of Affymetrix GeneChip arrays and statistical filtering, 529 genes/transcripts were considered to be differentially expressed in the diabetic rat cavernosum compared with control. Gene Ontology (GO) classification indicated that there was a decrease in numerous extracellular matrix genes (e.g., collagen and elastin related) and an increase in oxidative stress-associated genes in the diabetic rat cavernosum. In addition, PubMatrix literature mining identified differentially expressed genes previously shown to mediate vascular dysfunction [e.g., ceruloplasmin (Cp), lipoprotein lipase, and Cd36] as well as genes involved in the modulation of the smooth muscle phenotype (e.g., Kruppel-like factor 5 and chemokine C-X3-C motif ligand 1). Real-time PCR was used to confirm changes in expression for 23 relevant genes. Further validation of Cp expression in the diabetic rat cavernosum demonstrated increased mRNA levels of the secreted and anchored splice variants of Cp. CP protein levels showed a 1.9-fold increase in tissues from diabetic rats versus controls. Immunohistochemistry demonstrated localization of CP protein in cavernosal sinusoids of control and diabetic animals, including endothelial and smooth muscle layers. Overall, this study broadens the scope of candidate genes and pathways that may be relevant to the pathophysiology of diabetes-induced ED as well as highlights the potential complexity of this disorder.

Histological alterations in cavernous tissue after radical prostatectomy

PURPOSE

Radical prostatectomy often results in erectile dysfunction because of lesions to the erectile nerves. In this study we evaluated histomorphological alterations in cavernous smooth muscle and collagen content after radical prostatectomy.

MATERIALS AND METHODS

A total of 19 patients between 57 and 69 years old with prostate adenocarcinoma and normal erectile function, as reported and validated by RigiScan (UroHealth Systems, Laguna Niguel, California) testing, underwent corpora cavernosa biopsy in the operating room before radical prostatectomy, and 2 and 12 months after surgery. No patient underwent hormone therapy before or after surgery and none was diabetic. Elastic fibers (manual counting), muscle specific actin (immunostaining) and collagen content (computerized morphometric imaging) were measured in the 3 biopsies.

RESULTS

In all cases the first postoperative histological assessment revealed some disorganization. Trabecular elastic fibers (p <0.0003) and smooth muscle fibers were decreased and collagen content was significantly increased (p <0.0003) compared with preoperative biopsies. One year after surgery elastic fibers (p <0.0003) and smooth muscle fibers were decreased and collagen content was significantly increased (p <0.0003) compared with the first postoperative biopsy. Moreover, organized collagen and trabecular protocollagen deposits were increased.

CONCLUSIONS

Progressive fibrosis in the corpora cavernosa after radical prostatectomy probably results from denervation and/or an ischemic process, which is caused in turn by the ligation of anomalous pudendal artery branches or of venous plexuses that drain to or from the corpora cavernosa. Fibrosis and the subsequent loss in elasticity and function of erectile tissue probably together cause erectile dysfunction.

Ultrastructural comparison of penile cavernous tissue between hypertensive and normotensive rats

Our aim was to compare the ultrastructure of penile cavernous tissue in the spontaneous hypertensive rat (SHR) and normotensive rat, and study the relation of blood pressure with erectile function. After injection of apomorphine (APO), penile erectile frequency in 16-week-old SHR (group A) and Wistar-Kyoto rat (WKY) (group B) was observed and noted. The ultrastructure of the penile cavernous tissue was studied by scanning electron microscope and transmission electron microscope. The mean blood pressures were significantly higher in group A than in group B (P=0; 171.20+/-10.94 and 117.60+/-12.38, n=5, for group A and group B, respectively). After treatment of the two groups with APO, the erectile frequency in group A was significantly less than in group B (P=0.007; 0.40+/-0.55 and 2.40+/-1.14, n=5, for group A and group B, respectively). Significant ultrastructural pathological changes were observed in the tunica albuginea and penile cavernous tissue of SHR. The elastic fibers were decreased and the collagen fibers of the sinusoid were increased in group A. The tunica albuginea thickness (mean+/-s.d.) was 100.20+/-7.22 microm and 126.00+/-7.65 microm in group A and group B, respectively. The tunica albuginea of group A was significantly thinner than that in B (P=0.001). Some endothelial cells and smooth muscle cells exhibited damaged mitochondria, and endoplasmic reticulums and Schwann cells were degenerated in group A. Although the function of penile erection might be affected by a secondary effect related to endothelial dysfunction of hypertension, these ultrastructural pathological changes of the penile cavernous tissue might also be one of the important mechanisms of erectile dysfunction caused by hypertension.

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.

Effect of chronic ischemia on bladder structure and function

Our studies with the animal model show that arterial stenosis and insufficiency--a common problem in the elderly--lead to marked changes in bladder structure and function. Moderate chronic ischemia leads to functional and structural changes quite different from those caused by severe chronic ischemia. The extent of histopathophysiologic changes in the chronically ischemic bladder depends on the degree of arterial stenotic disease and the severity of bladder ischemia. Histopathophysiologic changes in our animal model appear to be similar in many ways to those reported in clinical detrusor instability. This would suggest that vascular risk factors and ensuing arterial obstructive disease and bladder ischemia might play an important role in the development of bladder dysfunction. A better understanding of the involvement of vascular risk factors in voiding dysfunction may lead to more accurate assessment of LUTS, precise patient selection for prostatectomy, and the development of prophylactic strategies and newer treatment.

Candesartan cilexetil protects cavernous tissue in spontaneously hypertensive rats

In previous experiments, our group demonstrated morphological changes in erectile tissue from male spontaneously hypertensive rats (SHR). The present study was performed to determine whether an angiotensin II receptor blocker could protect cavernous tissue (CT) from these structural alterations in SHR. Male SHR and Wistar-Kyoto (WKY) rats were studied during 4 months. Rats were divided into three groups: SHR (n=10), SHR with candesartan cilexetil (n=10) and WKY rats (n=10). Candesartan cilexetil 7.5 mg/kg/day was administered orally throughout the study. CT was processed for pathology studies. The amount of (1) cavernous smooth muscle (CSM), (2) vascular smooth muscle (VSM), (3) collagen type III, and the rat endothelial cell antibody (RECA-1)/tunica media ratio in cavernous arteries were evaluated. SHR with candesartan cilexetil showed a lower blood pressure, a lower percentage of CSM, smaller VSM area, with a higher RECA-1/media ratio, and a lower percentage of collagen type III, when compared to untreated SHR. In addition, SHR showed a positive correlation between systolic blood pressure (SBP) and CSM amount (r=0.91; P<0.01), and SBP and the percentage of collagen type III (r=0.88; P<0.01); these correlations were not observed either in SHR treated with candesartan cilexetil or in WKY rats. We conclude that candesartan cilexetil provides a significant protective role against morphologic changes in vessels as well as in cavernous spaces of the erectile tissue, caused by high blood pressure, in SHR.

[Erectile dysfunction]

In Spain, based on the IIEF, 19% of males between 25 and 70 years old present some degree of erectile dysfunction (ED). Therefore, around 2,000,000 Spanish men present this condition and could require medical attention for it. Here, we present an up-date of the most important aspects of erectile dysfunction (pathophysiology, diagnosis and treatment). We review, in detail, the oral treatments and future drugs that are presently in the premarketing experimental phase. Diagnostic and therapeutic management of the patient with erectile dysfunction should be individualized, taking into account the goals of each patient. It is highly recommendable to carry out a basic assessment (comprehensive clinical history, physical examination, recommended lab testing). If previously undiagnosed diseases are discovered (diabetes, arteriosclerosis, etc.) these should be treated and modifiable risk factors should be corrected. There are numerous therapeutic options for the treatment of erectile dysfunction. Replacement therapy with testosterone should only be used in males with ED and low levels of this hormone, under medical supervision. At present, first line treatment consists of the administration of oral drugs (sildenafil, apomorphine). There are two new PDE 5 inhibitors (tadalafil and vardenafil) that will be released on the market 2003, which will provide better selectivity. Moreover, several drugs for oral administration are in the initial phases of research that will facilitate erection via a direct penile action. When oral drugs are contraindicated, are not effective or when they are unpopular with the patient, the second line of treatment is intracavernous injection. Prostaglandin E1 is the initial drug of choice in patients using intracavernous autoinjection for the first time and has a high efficacy. Implantation of a penis prosthesis and penile revascularisation are appropriate for highly selected patients. Psychotherapy can be an option for men with ED of psychogenic origin, either as a monotherapy or combined with sildenafil or apomorphine.

Morphological changes in cavernous tissue in spontaneously hypertensive rats

Erectile dysfunction has an increased prevalence in hypertensive patients and is associated with cardiovascular diseases. For many years the discussion has been polarized on whether in hypertensive patients, it is the arterial hypertension or the antihypertensive therapy that is the cause of male erectile dysfunction. The aim of our study was to determine the morphologic changes in cavernous tissue (CT) in an animal model of arterial hypertension. Male spontaneously hypertensive rats (SHR) (n = 15) and normotensive Wistar-Kyoto (WKY) rats (n = 15) were studied for 8 months. Animals were allowed to drink tap water and fed a standard rat chow ad libitum. Systolic blood pressure (SBP) was measured monthly by the tail/cuff method. At the end of the experiment all the animals were sacrificed for microscopic studies. Cavernous tissue was processed by hematoxylin and eosin, Masson's trichrome, and monoclonal anti-alpha smooth muscle actin. Cavernous smooth muscle (CSM) and vascular smooth muscle (VSM) proliferation and CT fibrosis were evaluated by a semiquantitative score. SHR showed a higher proliferative score in CSM (2.7 +/- 0.28 v 1.1 +/- 0.07; P < .001), as well as in VSM (2.7 +/- 0.25 v 1 +/- 0.05; P < .001), and higher CT fibrosis score (2.8 +/- 0.28 v 0.1 +/- 0.07; P < .001), when compared to WKY rats. Furthermore, SHR showed a positive correlation between SBP and CSM proliferative score (r2 = 0.9277), SBP and VSM proliferative score (r2 = 0.8828), and SBP and CT fibrosis score (r2 = 0.7775). In addition, an increase in the surrounding connective tissue at the perineurium and endoneurium of the amielinic nerves in CT was observed in the SHR group. According to these results we conclude that SHR present morphologic changes in vessels as well as in cavernous spaces of the erectile tissue that have a high positive correlation with high blood pressure. Moreover, the increase in extracellular matrix expansion seems to affect not only the interstitium but also the neural structures of the penis.

Transforming growth factor-beta1 (TGF-beta1) is sufficient to induce fibrosis of rabbit corpus cavernosum in vivo

PURPOSE

The pleotropic cytokine TGF-beta1 which induces connective tissue synthesis, and inhibits the growth of smooth muscle cells, has been implicated in corpus cavernosum fibrosis. The objective of this study was to determine the dose and time dependence of TGF-beta1 as an active agent in penile corporal fibrosis in an animal model.

MATERIALS AND METHODS

A time release method of delivery was developed using sodium alginate microspheres containing recombinant human (rh) TGF-beta1. New Zealand White rabbits were injected intracorporally with a single alginate microsphere either with or without rh-TGF-beta1. Dosage was varied from 325 to 1500 ng./bead. Animals were sacrificed at either three or five days post injection and the penises removed en bloc, examined, and processed for quantitative histomorphometric analysis, staining the sections with Masson's trichrome.

RESULTS

Alginate microspheres containing [125I]-rh-TGF-beta1 showed slow-release kinetics (t1/2 = 10.5 hours). Histomorphometric analysis of 60 sets of high powered fields/treatment/ animal showed dose dependent decreases in percentage of corporal smooth muscle with TGF-beta1 treatment (750 to 1500 ng./bead). Placebo (alginate microspheres alone) had trabecular smooth muscle content comparable to values previously reported for untreated rabbit corpus cavernosum.

CONCLUSIONS

This study confirms that TGF-beta1 induces fibrosis in situ by altering connective tissue synthesis and hence the structure of the corpus cavernosum. Injection of rh-TGF-beta1 impregnated alginate microspheres into the corpus cavernosum resulted in dose-dependent decreases in percentage of corporal smooth muscle.

Electron microscopic findings of penile tissues in veno-occlusive dysfunction: is penile biopsy necessary?

In this study, we examined the biopsy patterns of penile tissues taken during operation from patients subjected to surgical treatment for veno-occlusive dysfunction, and evaluated the importance of penile biopsy. We evaluated the findings from 17 patients with venous impotence. Fourteen of them underwent total vein ligation and the rest penile prosthesis implantation. Tissue specimens taken from superficial and deep dorsal veins, tunica albuginea and corpus cavernosum during operation were examined under electron microscope. Tissue specimens taken from 3 cadavers were used as the control group. Although the deep and superficial vein specimens of all patients did not show significant differences, oedema and increase of fibroblasts in collagen fibres of the corpus cavernosum and tunica albuginea were demonstrated. We concluded that penile biopsy as an invasive method does not give enough information about the choice of treatment for erectile dysfunction.

Cavernosal expandability is an erectile tissue mechanical property which predicts trabecular histology in an animal model of vasculogenic erectile dysfunction

PURPOSE

Reliable, clinically available, non-invasive measurements able to predict trabecular histology without the need for erectile tissue biopsy would improve impotence management, since the percentage of trabecular smooth muscle content has been shown to be associated with corporal veno-occlusive dysfunction. The purpose was to identify whether the erectile tissue mechanical property, cavernosal expandability, correlated with the percentage of trabecular smooth muscle content in an animal model of hypercholesterolemia and ischemic-induced corporal fibrosis.

MATERIALS AND METHODS

New Zealand White rabbits (6 to 7 months old, 3 to 3.5 kg.), were divided into control (n = 7), hypercholesterolemic (n = 5, 0.5% cholesterol diet) and atherosclerotic groups (n = 8, 0.5% cholesterol diet with balloon de-endothelialization). At 16 weeks, the corpora cavernosa were removed en bloc and submerged in physiologic salt solution, and volume-pressure data were plotted at 20 mm. Hg pressure intervals under trabecular smooth muscle relaxation. Cavernosal expandability, X, (the measure of the ability to achieve high corporal expansion at relatively low intracavernosal pressure) and tunical distensibility, V(E)/V(F), (relative volume of fully erect to flaccid penis) were calculated. Erectile tissue was assessed by computer-assisted color histomorphometry with Masson's trichrome stained sections (30 to 45 high power fields/animal) to assess percentage of trabecular smooth muscle content.

RESULTS

The overall mean percentage of trabecular smooth muscle content and mean cavernosal expandability values were 45.4 +/- 1.6, 39.2 +/- 0.9, 33.9 +/- 0.6 and 0.0165 +/- 3.04 x 10(-3), 0.0116 +/- 1.63 x 10(-3), 0.0118 +/- 1.26 x 10(-3) mm. Hg(-1) for the control, hypercholesterolemic and atherosclerotic groups, respectively (r = 0.87). Significant differences in trabecular smooth muscle content were observed among all 3 groups, and in cavernosal expandability, between control and atherosclerotic groups, as well as between control and hypercholesterolemic groups but not between atherosclerotic and hypercholesterolemic groups.

CONCLUSIONS

The erectile tissue mechanical property, cavernosal expandability, correlated with erectile tissue structural quality. Since cavernosal histology has been shown to predict corporal veno-occlusive function, it is hypothesized that the measurement of cavernosal expandability may become a valuable functional clinical parameter in the diagnosis and treatment of men with erectile dysfunction.

Comparative study between corpus cavernosum-electromyography findings and electron microscopy of cavernosal muscle biopsies in erectile dysfunction patients

BACKGROUND

Biopsy and electrical activity recordings of the corpus cavernosum are 2 new diagnostic methods for the evaluation of impotent men. We evaluated the corpus cavernosum ultrastructure and electromyography (EMG) recordings from patients with erectile dysfunction.

METHODS

Twenty erectile dysfunction patients with veno-occlusive dysfunction underwent a detailed history, physical examination, biochemical tests, hormonal analysis, injection of an intracavernous vasoactive agent (60 mg papaverine-HCl), color penile Doppler ultrasonography, cavernosometry/ cavernosography and corpus cavernosum electromyography (CC-EMG). Thirteen patients underwent total vein ligation and 7 had penile prosthesis implantations. Tissue samples were obtained during surgery from both corpora cavernosa and examined by transmission electron microscopy. Control corporal tissue samples were taken from 3 cadavers.

RESULTS

In 15 patients, CC-EMG recordings were 15.6 +/- 0.65 microV in the flaccid state, which decreased in 13 patients after papaverine (5.61 +/- 0.25 microV; P < 0.001). Five patients with diabetes mellitus had low amplitudes in the flaccid state (5.26 +/- 0.45 microV), which did not vary significantly after a papaverine injection (4.99 +/- 0.75 microV). The pathology of the corpus cavernosum biopsy specimens revealed a smooth muscle cell thickened basal membrane, dilated rough endoplasmic reticulum, and increased numbers of fibroblasts, but ultrastructurally normal endothelial cells lining the sinusoids. There was no difference between samples from diabetic or nondiabetic patients, or from either side of the corpora cavernosa. The only pathologic change observed in the controls was mitochondrial swelling.

CONCLUSION

CC-EMG is less invasive and a valuable method in patients with erectile dysfunction, whereas no specific findings were observed from penile biopsy specimens.

Corporeal veno-occlusive dysfunction: predominantly intracavernous muscular pathology

PURPOSE

We investigated whether a relationship exists between the flow to maintain an erection obtained at cavernosometry and the alteration of intracavernous structures in impotent patients with corporeal veno-occlusive dysfunction and normal arterial inflow.

MATERIALS AND METHODS

Computerized histomorphometric analysis of smooth muscle and elastic fibers, and endothelial cells was compared to the flow necessary to maintain erection after intracavernous vasoactive drug injection in 18 patients with corporeal veno-occlusive dysfunction.

RESULTS

A significant correlation between percentage of smooth muscle fibers and flow to maintain erection was observed, while no correlation was noted with elastic fibers and endothelial cells.

CONCLUSIONS

Corporeal veno-occlusive dysfunction seems to be due mainly to smooth muscular alterations. According to this observation treatment of impotent patients with this abnormality should not be restricted to the penile veins but should also include the intracavernous structures, predominantly the muscular component.

Objective measurement of the different collagen types in the corpus cavernosum of potent and impotent men: an immunohistochemical staining with computerized-image analysis

Quantitative measurements of the collagen types (I, II, and IV) in the corpora cavernosa of potent and impotent men were carried out to investigate whether quantitative immunohistochemistry might contribute additional information as to the cause of erectile dysfunction. The study group consisted of 22 men with various etiologies of impotence and 4 normal, potent men. The quantitative immunohistochemistry measurements were performed by means of a cell-image processor. Three variables for each of the three types of collagen were studied, namely, the mean optical density (MOD), which relates to histochemical staining intensity; the labeling index (LI), which is positively related to the percentage of immunostaining; and the quick score (QS) index, which takes into account both LI and MOD values. None of the quantitative parameters taken individually (monovariate statistical analyses) made it possible to obtain any statistically significant difference between the types of collagen of the group under study. The mean QS value recorded for collagen type IV was significantly lower than that noted for collagen type I in the psychogenic (P = 0.019), arteriogenic (P = 0.012), and venogenic (P = 0.001) groups, whereas the MOD value was significantly lower in the normal (P = 0.043), arteriogenic (P = 0.013), and venogenic (P = 0.001) groups but not in the psycogenic group. The mean MOD of collagen type III was intermediate between that of the other types. In contrast, the mean LI value recorded for collagen type IV was significantly lower only in the venogenic (P = 0.032) and psychogenic (P = 0.049) groups as compared with the other groups. No objective qualitative change in the collagen types was observed that could be correlated to the etiology of erectile dysfunction. The significant difference seen in the quantitative parameters with regard to collagen type IV and the observed increase in the type I/III collagen ratio might attest to the notion that the response of the erectile tissue to ischemia is similar to that of other organs. The net effect of these changes is a restricted capacity for corporal expansion and alteration of the veno-occlusive mechanism.

Mechanisms of venous leakage: a prospective clinicopathological correlation of corporeal function and structure

PURPOSE

We investigated the pathophysiology of structurally based corporeal veno-occlusive dysfunction.

MATERIALS AND METHODS

We prospectively evaluated 24 impotent patients (mean age plus or minus standard error 46 +/- 3 years) who had exposure to vascular risk factors and/or disorders inducing diffuse trabecular structure alterations and who underwent penile prosthesis insertion. Preoperative indexes of veno-occlusive function (flow to maintain, venous outflow resistance and pressure decay measurements using repeat dosing pharmacocavernosometry) were correlated with postoperative erectile tissue computer assisted color histomorphometry (percent trabecular smooth muscle to total erectile tissue area). To develop further study findings and correlate histomorphometric findings with molecular biological properties molecular biological studies (ribonuclease protection analysis, reverse transcription-polymerase chain reaction assay for expression of transforming growth factor-beta 1 messenger [m] ribonucleic acid [RNA] and protein affinity labeling techniques for specific transforming growth factor-beta receptors) were performed in representative patients with high (39 to 43%), intermediate (30 to 37%) and low (13 to 29%) trabecular smooth muscle content (normal 42 to 50%).

RESULTS

Flow to maintain, venous outflow resistance and pressure decay values significantly correlated with trabecular smooth muscle cell content (r = -0.89, 0.82 and -0.85, respectively). In the high, intermediate and low smooth muscle content subgroups flow to maintain, venous outflow resistance and pressure decay values were 1 to 5, 9 to 30 and 50 to 120 ml. per minute, 17 to 84, 3 to 9 and 1 to 2 mm. Hg/ml. per minute, and 40 to 60, 48 to 80 and 110 to 120 mm. Hg decrease in 30 seconds from 150 mm. Hg, respectively. There were no significant differences in patient age or prevalence of risk factors among the 3 subgroups. Patients representative of all 3 subgroups had transforming growth factor-beta 1 mRNA, auto-induction of transforming growth factor-beta 1 mRNA and induction and/or increased availability of all 3 types of transforming growth factor-beta receptors.

CONCLUSIONS

The pathophysiology of structurally based corporeal veno-occlusive dysfunction is related to elevated corporeal connective tissue content. Based on our data and those in the literature corporeal fibrosis is hypothesized to develop secondary to abnormalities in the regulation of normal collagen synthesis and degradation, most likely associated with adverse influences of chronic ischemia.

Diabetic sexual dysfunction

Although the overall incidence of erectile dysfunction in the general population between the ages of 40 and 70 years is 52%, men with diabetes mellitus have impotence at an earlier age and with a significantly higher prevalence, ranging as high as 75%. Numerous advances have been made in understanding the physiologic and biochemical mechanisms controlling penile erection. Improved clinical techniques for the diagnosis and treatment of impotence, including dynamic vascular testing, intracavernosal pharmacotherapy, and microsurgical revascularization, have allowed us to enter a new and exciting era in the quest for a more complete understanding of erectile dysfunction.

Ultrastructual changes of corpora cavernosa in vascular erectile dysfunction

Corpora cavernosa of 4 impotent patients with arterial pathology and 6 with venous insufficiency were studied by electron microscopy. The findings in all of the smooth muscle samples were the following: pronounced thickening of the basal lamina; marked reduction of contractile myofilaments and electron dense bodies; finger-like cytoplasmic projections; increase in mitochondria with swelling and aggregation; huge protrusions of nuclear membrane into the cytoplasm; increased proportion of interstitial matrix to smooth muscle cells. These were more marked in the dark than in the light cells, which was considered as the beginning of degeneration. Another finding was degenerative changes in the endothelial cell lining of the sinusoids, especially denudation, fragmentation and marked thickening of the basal lamina. Severity of the symptoms did not change in any of the patients with different pathologies. So, we can assume that the pathological alterations may be due to chronic penile vascular insufficiency or vice versa.