EXPRESSION OF TGF-beta-1 mRNA AND ULTRASTRUCTURAL ALTERATIONS IN PHARMACOLOGICALLY INDUCED PROLONGED PENILE ERECTION IN A CANINE MODEL

The role of angiotensin receptor blocker (losartan) on decreasing fibrotic process of corpora cavernosa in priapism model of wistar rats

Background

Priapism induces regulation of Transforming Growth Factor-β1 (TGF-β1) expression and collagen-type-1 deposition. This will replace the normal corpora cavernosa with fibrotic tissue which eventually resulted in erectile dysfunction. It is also known that the fibrosis process of corpora cavernosa is related to Renin-Angiotensin II System (RAS). Angiotensin II receptor blockers (ARB), especially losartan, inhibit the inflammation process and fibrotic tissue formation. This study evaluated the effect of losartan in reducing fibrosis in priapism by evaluating TGF-β1 and collagen-type-1 in cavernous tissue and determined the effect of losartan in preventing fibrosis in priapism model of Wistar rats assessed by the metavir score.

Methods

A total of eighteen male Wistar rats mean were divided into five groups. For the priapism models, we applied negative pressure on the penis to make an artificial erection to mimic the priapism process. The control groups were observed and the treatment groups were orally given losartan 15 mg/kg/day. Corpora cavernosa was harvested for TGF-β1 and collagen-type-1 measurement using an enzyme-linked immunosorbent assay (ELISA). The fibrotic tissue of each rat was then collected and assessed histopathologically with the metavir scoring system.

Results

Penile TGF-β1 concentration in the losartan-treated group was not significantly different on day 10 and day 28 of observation (p10=0,30; p28=0,17). Meanwhile, collagen-type-1 concentration was significantly lower compared to control group (p10=0,002; p28=0,01). There was a significant difference in metavir scores in rats that received losartan and those who did not (p<0,05).

Conclusion

Losartan could suppress the fibrosis process in the priapism model. It could decrease the collagen type 1 deposition during corpora cavernosa tissue regeneration. Based on the metavir score, the group receiving losartan therapy was better than the control group.

Priapism or Prolonged Erection: Is 4 - 6 Hours of Cavernous Ischemia the Time Point of Irreversible Tissue Injury?

INTRODUCTION

Ischemic priapism remains a significant cause of morbidity among men. To date, the precise time when penile ischemia results in permanent, non-reversible cavernosal smooth muscle injury, compromising subsequent erectile integrity, remains ill-defined.

OBJECTIVES

To review the medical literature pertaining to ischemic priapism, focusing on factors that predict the exact timeline of irreversible cavernous tissue injury.

METHODS

A comprehensive literature search was performed. Our search included both publications on animal models and retrospective clinical series through January 2022. Articles were eligible for inclusion if they contained original data regarding nonreversible tissue injury on histology and/or provided a timeline of erectile function loss or preservation and had full text available in English.

RESULTS

Innovative studies in the 1990s using invitro models with strips of rabbit, rat, canine and monkey corpus cavernosal tissue demonstrated that anoxia eliminated spontaneous contractile activity and reduced tissue responsiveness to electrical field stimulation or pharmacological agents. The same models demonstrated that the inhibitory effects of field stimulated relaxation, were mediated by nitric oxide. Subsequent studies using similar models demonstrated that exposure of corpus cavernosum smooth muscle to an acidotic environment impairs its ability to contract. A pH of 6.9 was chosen for these experiments based on a case series of men with priapism, in whom a mean pH of 6.9 was measured in corporal blood after 4-6 hours of priapism. Invivo animal studies demonstrated that after erection periods of 6-8 hours, microscopy shows sporadic endothelial defects but otherwise normal cavernous smooth muscle. In these studies, greater durations of ischemic priapism were shown to result in more pronounced ultrastructural changes and presumably irreversibility. In studies involving human corporal tissues, samples were obtained from men who had experienced priapism for at least 12 hours. Overall, erectile function outcome data is deficient in priapism reporting, especially within treatment windows less than 6 hours. Some reports on ischemic priapism have documented good erectile function outcomes with reversal by 12 hours.

CONCLUSION

Based on our extensive review of animal models and clinical reports, we found that many clinical papers rely on the same small set of animal studies to suggest the time point of irreversible ischemic damage at 4-6 hours. Our review suggests an equal number of retrospective clinical studies demonstrate that ischemic priapism reversed within 6-12 hours may preserve erectile function in many patients. Dekalo S, Stern N, Broderick GA, et al. Priapism or Prolonged Erection: Is 4 - 6 Hours of Cavernous Ischemia the Time Point of Irreversible Tissue Injury? Sex Med Rev 2022;XX:XXX-XXX.

A pathophysiology-based approach to the management of early priapism

Priapism is a rare condition that involves persistent penile erection for greater than 4 h. Distinct variants exist, each with unique characteristics. Ischemic priapism is a painful medical emergency that may occur as a result of veno-occlusion leading to hypoxia and tissue death. Recurrent bouts of ischemic priapism, or stuttering priapism, require treatment for individual attacks as well as long-term prevention. Non-ischemic priapism is associated with trauma and may be managed conservatively. Recent advances into the pathophysiology of priapism have allowed the development of treatment algorithms that specifically target the mechanisms involved. In this review, we outline the basics of smooth muscle contraction and describe how derangement of these pathways results in priapism. A pathophysiological approach to the treatment of priapism is proposed with duration-based algorithms presented to assist in management.

Sickling cells, cyclic nucleotides, and protein kinases: the pathophysiology of urogenital disorders in sickle cell anemia

Sickle cell anemia is one of the best studied inherited diseases, and despite being caused by a single point mutation in the HBB gene, multiple pleiotropic effects of the abnormal hemoglobin S production range from vaso-occlusive crisis, stroke, and pulmonary hypertension to osteonecrosis and leg ulcers. Urogenital function is not spared, and although priapism is most frequently remembered, other related clinical manifestations have been described, such as nocturia, enuresis, increased frequence of lower urinary tract infections, urinary incontinence, hypogonadism, and testicular infarction. Studies on sickle cell vaso-occlusion and priapism using both in vitro and in vivo models have shed light on the pathogenesis of some of these events. The authors review what is known about the deleterious effects of sickling on the genitourinary tract and how the role of cyclic nucleotides signaling and protein kinases may help understand the pathophysiology underlying these manifestations and develop novel therapies in the setting of urogenital disorders in sickle cell disease.

Early insertion of inflatable prosthesis for intractable ischemic priapism: our experience and review of the literature

A cohort of 20 patients with delayed priapism who underwent treatment at the Emergency Department of our academic referral centers between January 2002 and April 2010 was studied. Of these, 16 cases suffered from a low-flow priapism. A total of 6 cases were managed non-surgically, 10 required shunt surgery, and of these 5 were treated by early penile prosthesis surgery. Prostheses were easily implanted in all patients with a mean operative time of 94 min. No intraoperative complications and no infection were registered. All patients with an inflatable prosthesis complained a reduction in penile sensibility that lasted 3 months. All patients were satisfied with the results of surgery (International Index of Erectile Function Questionnaire-5, Q5 mean value 4), and all were successfully engaging in satisfactory sexual intercourses. No significant loss of penile length, neither apical erosion nor extrusion was recorded. Early insertion of a penile prosthesis is a simple and safe procedure in patients with ischemic priapism, which failed to respond to conservative management. Early insertion of a prosthesis helps to maintain adequate penile length, resolve priapism and, in the long term, it results in high satisfaction rates.

In vitro and in vivo animal models in priapism research

INTRODUCTION

Priapism is an enigmatic yet devastating clinical phenomenon. In the last two decades, the use of various animal models to study this disorder has dramatically advanced our understanding of this mysterious disorder.

AIM

This report reviews various animal models used to study ischemic priapism and informs basic science researchers the broad view of priapism research.

METHODS

Retrospective review of pertinent literature from the last two decades via PubMed search using the keywords "ischemic priapism" and "priapism model."

MAIN OUTCOME MEASURES

  Findings on the animal models used in ischemic priapism research and its advantages and limitations.

RESULTS

In vitro and in vivo animal models varying from dogs, cats, rabbits, rats to mice were used in priapism research. In vitro models included: (i) corpora cavernosa smooth muscle (CCSM) strip in organ bath; (ii) corporal tissue binding assay; (iii) CCSM cell culture under hypoxia/anoxia. In vivo models could be categorized as: (i) pharmacologically induced by corpus cavernosum medicine injection; (ii) ventilation induced by tidal volume control; (iii) mechanical induced by a constrictor band placed around the base of the penis combined with induced erection; (iv) genetic engineered by intracorporal gene transfer, transgenic, or gene knock-out.

CONCLUSIONS

The ischemic priapism animal models are shifting from pharmaceutically or mechanically induced to genetically engineered. The knowledge generated by those models is enhancing our understanding and management of this clinical challenge.

Establishment of a transgenic sickle-cell mouse model to study the pathophysiology of priapism

INTRODUCTION

Priapism is a poorly understood disease process with little information on the etiology and pathophysiology of this erectile disorder. One group of patients with a high prevalence of priapism is men with sickle-cell disease.

AIM

Establish an in vivo transgenic sickle-cell mouse model to study the pathophysiology of sickle-cell disease-associated priapism.

METHODS

Transgenic sickle-cell disease mice, expressing human sickle hemoglobin, were utilized. Three groups of mice were used: (i) wild type (WT), (ii) sickle-cell heterozygotes (Hemi), and (ii) sickle-cell homozygotes (Sickle). Two age groups of each cohort of mice were utilized: young adult (4-6 months) and aged (18-22 months).

MAIN OUTCOME MEASURES

Histological (trichrome stain to measure ratio of collagen to smooth muscle), penile hydroxyproline content (collagen content), and transmission electron microscopic analysis of WT, Hemi, and Sickle mice penes, as well as in vivo erectile responses [change in intracavernous pressure (ICP)] to cavernous nerve stimulation (CNS), were determined. The frequency of erectile responses (erections/hour) pre- and poststimulation was also measured in each of the experimental groups.

RESULTS

Sickle mice had increased (P < 0.05) collagen to smooth muscle ratio and hydroxyproline content in the penis when compared with WT and Hemi mice penes. Transmission electron microscopy demonstrated thickened smooth muscle cell bundles, disruption of the endothelial lining of the corporal sinusoids, and increased (P < 0.05) caveolae number. Sickle mice had significantly (P < 0.05) higher ICP to CNS and increased (P < 0.05) frequency of erections pre- and post-CNS when compared with WT and Hemi mice erectile responses. Sickle mice did develop ED (change in ICP in response to CNS) with increasing age.

CONCLUSION

The morphometric changes of the penis and exaggerated in vivo erectile responses support the use of this transgenic sickle-cell disease animal model to study the pathophysiological mechanisms involved in sickle-cell disease-associated priapism.

Priapism: New concepts in the pathophysiology and new treatment strategies

Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process, and we have little information on the etiology and pathophysiology of this erectile disorder. Two main types of priapism exist: low-flow (ischemic) and high-flow (nonischemic) priapism. When the physician first diagnoses which type of priapism exists, distinguishing the type of priapic event is paramount in order to choose the correct treatment options. Until recently, we had not sufficiently understood the pathogenesis of this erectile disorder and therefore, could not effectively manage its pathologic consequences of erectile tissue damage and erectile dysfunction. In this review, the proposed pathogenesis of ischemic priapism is reviewed, and a survey regarding novel treatment modalities is given.

TGF-beta1 neutralizing antibodies decrease the fibrotic effects of ischemic priapism

The objective of this study was to evaluate the possible role of transforming growth factor beta 1 (TGF-beta1) antibodies (ab) for the prevention of fibrotic effects of priapism in a rat model. In total, 30 adult Sprague-Dawley rats were divided into five groups. Priapism with 6 h (group 1), priapism with 6 h+ab (group 2), priapism with 24 h (group 3), priapism with 24 h+ab (group 4) and control (group 5). Priapism was induced with a vacuum erection device and a rubber band was placed at the base of the erect penis. At 1 h after the initiation of priapism, TGF-beta1 antibodies were given intracavernosaly. All rats underwent electrical stimulation of the cavernous nerve after 8 weeks. Intracavernous and systemic blood pressures were measured during the procedure. Rats in group 1 showed significantly higher (intracavernosal pressure (ICP) pressures to cavernous nerve stimulation and had higher ICP/BP ratios when compared to other groups. Similarly, histopathologic examination revealed less fibrosis in group 2, compared with the other groups. Consequently, TGF-beta1 antibodies antagonise the fibrotic effects of TGF-beta1, especially in cases with duration of priapism less than 6 h.

Priapism

INTRODUCTION

There are three different types of priapism: low-flow, ischemic, anoxic or veno-occlusive priapism; high-flow, arterial or nonischemic priapism; and recurrent or stuttering priapism.

AIM

To provide recommendations/guidelines concerning state-of-the-art knowledge for the diagnosis and treatment of priapism.

METHODS

An International Consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a process over a 2-year period. Concerning the Priapism Committee, there were 10 experts from six countries.

MAIN OUTCOME MEASURE

Expert opinion was based on grading of evidence-based medical literature, widespread internal committee discussion, public presentation and debate.

RESULTS

Concerning ischemic priapism, persistent cavernous smooth muscle relaxation and failure of contraction is a compartment syndrome with increasing intracavernosal anoxia, rising pCO2 and acidosis. Urgent medical attention should be sought for an erection lasting >4 hours; 90% with priapism >24 hours develop complete erectile dysfunction. After diagnosis and counselling, intracavernosal aspiration and alpha-blockers should precede surgical shunting. Concerning high-flow priapism (congenital, traumatic or iatrogenic), intervention is not urgent and often unnecessary. Definitive management is by selective embolization with autologous blood clot. Concerning recurrent/stuttering priapism, the pathophysiology may be central or local (sickle cell disease). Management needs to be individualized; androgen deprivation has proved useful but has adverse effects.

CONCLUSIONS

There is need for prospective, clinical trials to define safe and effective management strategies for patients with low-flow, high-flow or recurrent priapism.

Pathophysiology of priapism: dysregulatory erection physiology thesis

PURPOSE

While a modest amount of medical literature has been written on the topic of priapism, reports heretofore have focused predominantly on diagnostic and management related aspects of the disorder, providing meager information in regard to its pathophysiology. Accordingly the intent of this review was to explore the etiological and pathogenic factors involved in priapism.

MATERIALS AND METHODS

The review entailed an overview of traditional and modern concepts that have been applied to the pathophysiology of priapism and an evaluation of assorted observational and experimental data relating to this field of study. The basic exercise consisted of a literature search using the National Library of Medicine PubMed Services, index referencing provided through the Historical Collection of the Institute of Medicine of The Johns Hopkins University and a survey of abstract proceedings from national meetings relevant to priapism.

RESULTS

Insight into the pathophysiology of priapism was derived from a synthesis of evolutionary clinical experiences, mythical beliefs, clinical variants and scientific advances associated with the field of priapism. The results can be summarized. 1) Clinicopathological manifestations of priapism support its basic classification into low flow (ischemic) and high flow (nonischemic) hemodynamic categories, commonly attributed to venous outflow occlusion and unregulated arterial overflow of the penis, respectively. 2) Factual information is insufficient to substantiate etiological roles for urethral infection, bladder distention, failed ejaculation, satyriasis and sleep apnea in priapism. 3) Features of the variant forms of priapism invoke changes in nervous system control of erection and penile vascular homeostasis as having pathogenic roles in the disorder. 4) Clinical therapeutic and basic science investigative studies have revealed various effector mechanisms of the erectile tissue response that may act in dysregulated fashion to subserve priapism.

CONCLUSIONS

This exercise suggested that, while priapism is commonly defined in terms of adverse mechanical contexts affecting penile circulation, it may also be viewed at least in some situations as an unbalanced erectile response involving derangements in possibly diverse systems of regulatory control. An integrative scientific approach that encompasses tissular, cellular and molecular levels of investigation may allow further understanding of the pathophysiology of the disorder. Ongoing elucidation of this pathophysiology can be expected to promote the development of new priapism therapies.

Priapism: a review

Priapism is persistent penile erection in the absence of sexual stimulation. The pattern of blood flow to the penis that occurs during normal erection is altered so that sustained priapism may result in edema, increased risk of abrasion, tissue drying and necrosis of the penis. Numerous causes have been reported in animals and humans. The prognosis depends on the type of priapism and the amount of time that passes before therapeutic intervention. Surgical methods, such as aspiration and shunting procedures, have traditionally been used to treat priapism but carry a risk of postsurgical complications. Use of alpha-agonists for treatment of priapism in humans is often successful and avoids the risks of impotence and other surgical complications. Investigation of the use of alpha-agonists for treatment of priapism in animals should be considered.

O2-dependent prostanoid synthesis activates functional PGE receptors on corpus cavernosum smooth muscle

We have previously demonstrated that decreased O2 tension inhibits prostaglandin synthesis from human corpus cavernosum smooth muscle cells in static culture over 8-18 h (R. B. Moreland et al., Molecular Urology 2: 41-47, 1998). In this report, an experimental system was designed that allowed determination of the effects of O2 tension changes over the time frame of physiological penile erection. Human corpus cavernosum smooth muscle cells were cultured on microcarrier beads in enclosed stirrer flasks so that rapid changes of O2 tension could be modulated. After 18 h of equilibration at 30-40 mmHg to simulate blood PO2 at penile flaccidity, O2 tension was increased to 100 mmHg for 1 h and then returned to 30-40 mmHg. Media samples were withdrawn for prostanoid synthesis and cell samples were taken for cAMP determinations. After 18 h of 30-40 mmHg PO2 values, prostanoid synthesis by human corpus cavernosum smooth muscle cells was low (0.1-0.7 pmol/10(6) cells). When PO2 was increased to 100 mmHg, a rapid increase in PGE2 >> PGF2alpha > PGD2 was observed (thromboxane A2 was undetectable), which peaked at 5.7 pmol PGE2/10(6) cells. Increased O2 tension correlated with increased PGE2 and increased intracellular synthesis of cAMP. The prostaglandin G/H synthase inhibitor indomethacin or the E prostanoid (EP2)-selective antagonist AH-6809 each inhibited the O2-tension-dependent increases in cAMP. These data support a role of differential O2 tension in the penis in the smooth muscle synthesis of PGE2, which in turn increases cAMP synthesis via EP2 receptors.

Priapism. From Priapus to the present time

Advances in the pharmacotherapeutic options available to treat erectile dysfunction over the past decade have transformed the field of impotence. The initial foray into this field with intracavernous injections of papaverine rapidly expanded the number of men seeking attention for priapism, a previously rare clinical condition. The recent widespread use and acceptance of oral agents for the treatment of erectile dysfunction, with a reduced incidence of priapism has decreased the number of men at risk for injection-related prolonged erections. The use of recreational drugs (cocaine) and perineal trauma leading to presentations of priapism seem to be rising in incidence. The urologist remains the consultant-specialist ultimately responsible for these men and should be cognizant of the array of treatments described for this condition. Early determination of the state of corporal oxygenation is essential and will define the optimal management approach. A wide range of medical conditions and risk factors may be etiologic and should be elicited from the patient at the initial interview. Low-flow ischemic priapism requires a rapid resolution, often achieved through use of alpha-agonists orally or by direct injection into the penile circulation, whereas nonischemic priapism can be treated more conservatively. Research into this condition has only recently been initiated. Through greater understanding of the pathophysiology of priapism, the clinician may become armed with etiology-specific medical alternatives providing timely detumescence for men with prolonged erections.

Pharmacotherapeutic advances in the treatment of erectile dysfunction

An estimated 20 million to 30 million American men have erectile dysfunction (ED). The past 2 decades of research defining erectile physiology and investigating the pathogenesis of ED have led to the recognition of a predominantly vascular basis for organic male sexual dysfunction. These scientific advances have laid the foundation for the advent of pharmacotherapies. The Food and Drug Administration approval of intracavernosal, intraurethral, and oral pharmacotherapeutics for ED has revolutionized non-surgical management of this condition. The primary care physician is faced with the challenges of diagnosis and treatment of ED, as well as referral of patients to urologists. In this article, erectile physiology and pathophysiology are reviewed, and pharmacotherapeutics are classified and discussed by their mechanisms of action and the means of administration. A thorough understanding of these new therapeutic options is key to the accurate diagnosis and successful treatment of ED and maximal patient satisfaction and care.