The effects of oxytocin on penile tissues in experimental priapism model in rats

Intracavernosal mesenchymal stem cell therapy in ischaemic priapism: an experimental study

INTRODUCTION

The most common form of priapism is ischaemic and its prevalence in men has increased in recent years as a result of intracavernosal drug use. Currently, there is no approved specific treatment for ischaemic priapism other than cavernosal aspiration, which can only provide detumescence. This study aims to evaluate the efficacy of intracavernosal mesenchymal stem cell (MSC) therapy in an ischaemic priapism model.

MATERIAL AND METHODS

Thirty male Wistar albino rats were divided into three groups: sham (n = 6), priapism (n = 12) and priapism + MSC treatment (n = 12). The experimental groups were also divided into 1 and 12 h subgroups of ischaemic priapism. The experimental model was created using a vacuum erection device and constrictive tape technique, and intracavernosal MSC were applied immediately after the tape was removed. After 4 weeks, intracavernosal pressures (ICPs) and systemic mean arterial pressure (MAP) were measured. Penectomy was then performed to assess histopathological and molecular changes in the rats' penile tissues.

RESULTS

In the ischaemic priapism model, MSC therapy showed significant improvements in peak and mean ICPs and mean ICP/MAP ratio. Histopathological analysis showed significant increases in smooth-muscle/collagen ratio and e-NOS and n-NOS expression. Although there was a decrease in fibrosis, it was not significant. At the molecular level, there were significant decreases in TGF-beta and VEGF mRNA expression, whilst NGF and BDNF mRNA-expression levels showed significant increases with MSC therapy. In terms of ICPs, the therapy showed more significant improvements in short-term priapism. However, when looking at histopathological and molecular parameters, the therapy had positive effects on a wider range of parameters in the long-term priapism.

CONCLUSION

MSC treatment improved cavernosal physiology and had positive effects at the histopathological and molecular level in the ischaemic priapism model.

An Experimental Rat Model Study: Is There Any Effect of Syringic Acid on Ischemia-Reperfusion Injury in Priapism?

Purpose The purpose of this research is to examine the impact of syringic acid on ischemia-reperfusion injury in cavernosal tissue, utilizing a rat model of induced priapism. Materials and methods A total of 24 rats were allocated into three groups. Group 1 was designated as the control group, while Group 2 underwent ischemia-reperfusion injury assessment using the priapism model. Group 3 underwent the same procedures as Group 2, with the addition of intraperitoneal administration of syringic acid (100 mg/kg) 60 min after priapism initiation. All rats underwent penectomy, and sufficient blood samples were collected. Histopathological assessment of penile cavernosal tissue involved grading tissue damage, inflammation, vasocongestion, desquamation, and edema on a scale of 0-3 (0: normal, 1: mild, 2: moderate, 3: severe). Result Significant differences were observed among the three groups in terms of IL-1 beta and TNF-alpha levels (p=0.001 and p<0.001, respectively). IL-1 beta and TNF-alpha levels in Group 2 were found to be significantly higher than Group 3 (p=0.003 and p=0.004). There was also a significant difference among the three groups in terms of median MDA levels (p<0.001). Furthermore, the median MDA level in Group 2 was found to be significantly higher than that in Group 3 (p<0.001). While significant differences were observed among the three groups in terms of median SOD and GSH-px levels, no significant difference was found among the groups in terms of median PC levels (p=0.004, p= 0.048, and p=0.159, respectively). In direct microscopic examination, a significant improvement in pathological scores was noted in Group 3 compared to Group 2 (p<0.001). Conclusion Syringic acid demonstrated protective properties against ischemia-reperfusion injury caused by priapism in cavernosal tissue.

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.