In vivo rat model to measure hypogastric nerve stimulation-induced seminal vesicle and vasal pressure responses simultaneously

Direct Administration of Nerve-Specific Contrast to Improve Nerve Sparing Radical Prostatectomy

Nerve damage remains a major morbidity following nerve sparing radical prostatectomy, significantly affecting quality of life post-surgery. Nerve-specific fluorescence guided surgery offers a potential solution by enhancing nerve visualization intraoperatively. However, the prostate is highly innervated and only the cavernous nerve structures require preservation to maintain continence and potency. Systemic administration of a nerve-specific fluorophore would lower nerve signal to background ratio (SBR) in vital nerve structures, making them difficult to distinguish from all nervous tissue in the pelvic region. A direct administration methodology to enable selective nerve highlighting for enhanced nerve SBR in a specific nerve structure has been developed herein. The direct administration methodology demonstrated equivalent nerve-specific contrast to systemic administration at optimal exposure times. However, the direct administration methodology provided a brighter fluorescent nerve signal, facilitating nerve-specific fluorescence imaging at video rate, which was not possible following systemic administration. Additionally, the direct administration methodology required a significantly lower fluorophore dose than systemic administration, that when scaled to a human dose falls within the microdosing range. Furthermore, a dual fluorophore tissue staining method was developed that alleviates fluorescence background signal from adipose tissue accumulation using a spectrally distinct adipose tissue specific fluorophore. These results validate the use of the direct administration methodology for specific nerve visualization with fluorescence image-guided surgery, which would improve vital nerve structure identification and visualization during nerve sparing radical prostatectomy.

Dapoxetine and the treatment of premature ejaculation

Background

Premature ejaculation (PE) is the most common male sexual complaint. Off-label oral selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for the treatment of PE. Dapoxetine is a short-acting SSRI specifically designed for on-demand use. The objective of this communication is to summarize the clinical and physiological evidence regarding the role of the serotonergic pathway and specifically dapoxetine in the treatment of PE.

Methods

A PubMed search was conducted on articles reporting data on dapoxetine for the treatment of PE. Articles describing the pathophysiology and treatment options for PE were additionally included for review.

Results

The etiology of PE is multi-factorial in nature. There are many treatment options for PE such as psychological/behavioral therapy, topical anesthetic agents, phosphodiesterase type 5 (PDE-5) inhibitors, and tramadol hydrochloride. SSRIs play a major role in PE treatment. Animal and clinical studies in addition to its pharmacokinetic document dapoxetine’s clinical efficacy and safety for on-demand treatment of PE.

Conclusions

Dapoxetine demonstrates clinical efficacy and a favorable side effect profile. Dapoxetine is currently the oral drug of choice for on-demand treatment of PE.

New Methodology for Investigating Ejaculation Dysfunction: Measuring Intraluminal Seminal Vesicle Pressure in Rats with a Telemetric Device

INTRODUCTION

Ejaculation dysfunction is one of the most common male sexual disorders. Despite its prevalence and adverse impact on patients, little attention has been given to investigating ejaculation dysfunction.

AIM

We introduce a new method for evaluating ejaculation dysfunction in rats with a telemetric device.

METHODS

A pressure transducer was surgically implanted in the seminal vesicles of 7-week-old male Sprague-Dawley rats. One week later, the rats were subcutaneously administered tamsulosin 3 μg/kg, and intra-seminal vesicle pressure (ISVP) was recorded in freely moving rats after an injection of apomorphine (80 μg/kg). Same rats repeated experiment with tamsulosin 10 μg/kg, silodosin 1 mg/kg, and normal saline with 3-day intervals.

MAIN OUTCOME MEASURE

Sexual events were visually identified and recorded. Ejaculation was confirmed by visualization of a copulatory plug in the tip of the penis. We compared the maximal ISVP and area under the curve (AUC) of the ISVP.

RESULTS

Adequate ISVP data were easily recorded and available in 66.6% rats (10/15) over a 6-week telemetric recording period (12 recordings). The mean number of ejaculations during an inspection time of 30 minutes was 1.5 ± 0.1. The maximal ISVP values in rats receiving 3 μg/kg (30.0 ± 5.2 mm Hg) and 10 μg/kg tamsulosin (15.1 ± 1.6 mm Hg) and 1 mg/kg silodosin (12.9 ± 2.2 mm Hg) were significantly lower than that in control rats (61.4 ± 13.4 mm Hg, P < 0.05). The AUC values in rats receiving 3 μg/kg (72.7 ± 18.9 mm Hg × s) and 10 μg/kg tamsulosin (23.5 ± 6.1 mm Hg) and 1 mg/kg silodosin (23.9 ± 8.0 mm Hg) were also lower than that of control rats (162.6 ± 34.3 mm Hg, P < 0.05).

CONCLUSIONS

Telemetric ISVP assessment is reliable and feasible for investigating apomorphine-induced ejaculation in rats. Tamsulosin (3 μg/kg and 10 μg/kg) and silodosin 1 mg/kg decreased the ISVP during ejaculation.

Effects of tamsulosin on premature ejaculation in men with benign prostatic hyperplasia

PURPOSE

Previous studies have revealed that tamsulosin is effective in improving lower urinary tract symptoms (LUTS) and erectile functioning but has some inhibitory effects on ejaculation, including decreased ejaculatory volume. However, these inhibitory effects on ejaculation can be beneficial to patients with premature ejaculation (PE). Therefore, this study was conducted to understand the effect of tamsulosin on PE in men with benign prostatic hyperplasia.

MATERIALS AND METHODS

Twenty-nine patients who visited with LUTS were categorized into 2 groups of LUTS-only patients (n=12) and LUTS combined with PE (LUTS+PE) patients (n=17), and 0.4 mg of tamsulosin was administered to the patients of both groups for 12 weeks. Comparative analyses of before and after the treatment were conducted for calculating the International Prostate Symptom Score (IPSS), International Index of Erectile Function-5 (IIEF-5), intravaginal ejaculatory latency time (IELT), premature ejaculation diagnostic tool (PEDT), and premature ejaculation profile (PEP). The patients with an IPSS score of 8 or higher were determined as LUTS patients, and the patients with IELT of less than 2 minutess and a PEDT score of 9 or higher were determined as PE patients.

RESULTS

After treatment, the IPSS score significantly decreased in both groups. There was no statistically significant change in the PEDT for the LUTS group, but there was a significant decrease in PEDT (p=0.012; from 12.1±3.31 to 8.4±4.49) in the LUTS+PE group.

CONCLUSIONS

Tamsulosin not only has a treatment effect for LUTS but also improves the PE of LUTS+PE patients. Therefore, further studies are needed to confirm the effects of tamsulosin on PE.

Dapoxetine, a novel selective serotonin transport inhibitor for the treatment of premature ejaculation

Premature ejaculation (PE) is the most common male sexual disorder, estimated to affect up to 30% of men. Over the past one or two decades, clinical investigators have participated in an increasing number of studies that are helping in our understanding of PE, which will undoubtedly facilitate future treatments. Apart from a number of behavioral approaches, the treatment of PE consists of primarily off-label use of oral selective serotonin reuptake inhibitors (SSRIs) via either on-demand or daily delivery. However, various undesirable side-effects of these medications have led researchers to search for and develop new therapeutic approaches for PE. Dapoxetine is a short-acting SSRI developed specifically for the treatment of PE. Early trials with dapoxetine have documented successful outcomes without serious short- or long-term side-effects. This review addresses the definition, classification, diagnosis, physiology, and neurobiopathology of PE, and evaluates therapeutic strategies with novel treatments for PE.

9-hydroxycanthin-6-one induces penile erection and delays ejaculation

INTRODUCTION

Eurycoma longifolia Jack (Simaroubaceae) has the reputation as a male aphrodisiac because it is claimed to increase virility and sexual prowess. Nevertheless, whether or not E. longifolia regulates directly the muscle tone of corpus cavernosa and/or seminal vesicle (SV) remains unclear. Even until now, the compositions that could account for its aphrodisiac property are still unknown

AIM

We examined the effect of 9-hydroxycanthin-6-one (9-HC-6-one), a β-carboline alkaloid isolated from E. longifolia, on penile erection and ejaculation, and further elucidated the mechanism of action.

MAIN OUTCOME MEASURES

9-HC-6-one induces penile erection and delays ejaculation.

METHODS

Drug's effect was studied on rat corpus cavernosum (CC) and SV in vitro, and on the changes in intracavernosal pressure (ICP) after IC injection and intraluminal pressure (ILP) of the SV after hypogastric nerve stimulation (HNS), respectively.

RESULTS

9-HC-6-one relaxed significantly phenylephrine (PE)-precontracted CC. Such response was not attenuated by endothelium disruption, N(G) -nitro-L-arginine methyl ester, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one treatment, suggesting that a nitric oxide/cyclic guanosine monophosphate-dependent pathway was precluded. 9-HC-6-one attenuated PE-induced contraction by blocking cell surface and internal calcium channels with a higher potency for internal calcium release. This compound also antagonized calcium-evoked contraction in Ca2+ -free, high K+ -depolarizing condition, suggesting that interfering with the entry of calcium through voltage-dependent channels also contributed to 9-HC-6-one-induced corporal relaxation. After IC application of 9-HC-6-one, a significant rise in ICP was observed as compared with the application of normal saline. 9-HC-6-one relaxed significantly norepinephrine (NE)- and KCl-precontracted SV, and antagonized NE-induced oscillatory contraction as potent as clomipramine. Finally, the HNS-evoked increase in ILP was dose-dependently repressed after challenge by 9-HC-6-one.

CONCLUSION

9-HC-6-one might be the active component that contributed to the aphrodisiac effect of E. longifolia by antagonizing the smooth muscle tone of CC as well as SV probably through interfering with Ca2+ mobilization.

Current therapeutic strategies for premature ejaculation and future perspectives

Premature ejaculation (PE) is a common sexual disorder in men that is mediated by disturbances in the peripheral and central nervous systems. Although all pharmaceutical treatments for PE are currently used 'off-label', some novel oral agents and some newer methods of drug administration now provide important relief to PE patients. However, the aetiology of this condition has still not been unified, primarily because of the lack of a standard animal model for basic research and the absence of a widely accepted definition and assessment tool for evidence-based clinical studies in patients with PE. In this review, we focus on the current therapeutic strategies and future treatment perspectives for PE.

Future sexual medicine physiological treatment targets

INTRODUCTION

Sexual function in men and women incorporates physiologic processes and regulation of the central and peripheral nervous systems, the vascular system, and the endocrine system. There is need for state-of-the-art information as there is an evolving research understanding of the underlying molecular biological factors and mechanisms governing sexual physiologic functions.

AIM

To develop an evidence-based, state-of-the-art consensus report on the current knowledge of the major cellular and molecular targets of biologic systems responsible for sexual physiologic function.

METHODS

State-of-the-art knowledge representing the opinions of seven experts from four countries was developed in a consensus process over a 2-year period.

MAIN OUTCOME MEASURES

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

RESULTS

Scientific investigation in this field is needed to increase knowledge and foster development of the future line of treatments for all forms of biological-based sexual dysfunction. This article addresses the current knowledge of the major cellular and molecular targets of biological systems responsible for sexual physiologic function. Future treatment targets include growth factor therapy, gene therapy, stem and cell-based therapies, and regenerative medicine.

CONCLUSIONS

Scientific discovery is critically important for developing new and increasingly effective treatments in sexual medicine. Broad physiologic directions should be vigorously explored and considered for future management of sexual disorders.

Characterization of the effects of various drugs likely to affect smooth muscle tension on isolated human seminal vesicle tissue

OBJECTIVES

To investigate the effects of different classes of drugs on the isometric tension of isolated human seminal vesicle (SV) tissue. The contractility of human SV contributes to the process of seminal emission during ejaculation. Different endogenous compounds, such as serotonin (5-HT), adenosine triphosphate (ATP), and nitric oxide, have been suggested to be involved in the control of contraction and relaxation of human SV smooth muscle. However, only limited data are available regarding the effects of compounds known to affect smooth musculature on SV contractile activity.

METHODS

Using the organ bath technique, the effects of increasing concentrations (10 nm-1 microm/10 microm) of norepinephrine (NE), phenylephrine, endothelin 1, ATP, and 5-HT on human SV tissue at basal tension were studied. In another set-up, SV strip preparations were preincubated with prazosin (alpha-adrenergic blocker), nifedipine and verapamil (Ca(2+)-channel blockers), 2-aminoethoxydiphenyl borate [inositol 1,4,5-trisphosphate (IP(3)) antagonist], cromakalim (K(+)-channel opener), or Y-27632 (ROK inhibitor) (1 microm each, for 10 minutes), followed by the application of NE (0.1 microM, 1 microM, and 10 microm).

RESULTS

SV smooth muscle was most effectively contracted by NE (mean = 75% of calibrated scale), phenylephrine (mean = 82% of calibrated scale), and endothelin 1 (mean = 70% calibrated scale), whereas only minor responses to ATP (mean = 10.65% calibrated scale) and 5-HT (mean = 6.3% calibrated scale) were observed. The contraction induced by NE was significantly inhibited after pre-exposure of the tissue to prazosin (-92.4%), cromakalim (-83.7%), 2-aminoethoxydiphenyl borate (-43.1%), Y-27632 (-42.8%), and nifedipine (-32.7%).

CONCLUSIONS

alpha-adrenoceptor antagonism, activation of potassium channels, and inhibition of Rho-kinase decrease the sympathetic contraction of SV smooth muscle. This might be of significance with regard to the identification of new pharmacologic avenues to affect the male ejaculatory system.

Premature ejaculation: current and future treatments

Premature ejaculation (PE) is recognized to be the most common male sexual disorder. PE provides difficulties for professionals who treat this condition because there is neither a universally accepted definition nor a medication approved by the Food and Drug Administration (FDA). Despite these shortcomings, physicians continue to diagnose their patients with PE according to major guidelines and treat them with either behavioral therapies or off-label medications. This review focuses on current and emerging treatment options and medications for PE. Advantages and limitations of each treatment option are discussed in the light of current published peer-reviewed literature.

Can smooth muscle represent a useful target for the treatment of rapid ejaculation?

Rapid ejaculation is probably the most common form of male sexual dysfunction. Current research into the treatment of the condition has focused on centrally acting or topical desensitizing agents; however, no treatment has yet been approved. An alternative approach could be to develop drugs that act directly upon the target organ itself and our increasing knowledge of the molecular biology of the accessory sex organs makes this a realistic possibility. This review analyzes the information in the literature that would support such a hypothesis. Particular emphasis has been placed on articles that have investigated smooth muscle cell relaxation. A critical review of the literature has revealed that there are potentially a myriad of targets through which rapid ejaculation can be treated.