Erectile dysfunction in spontaneously hypertensive rats: pathophysiological mechanisms

Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats

BACKGROUND

Botulinum toxin A (BTX-A) has a variety of uses in medicine. Some evidence suggests that intracavernosal (ic) BTX-A injection administered in addition to phosphodiesterase type 5 inhibitors (PDE5-Is) could effectively treat erectile dysfunction (ED) in insufficient responders to PDE5-Is.

AIM

To provide experimental pharmacological evidence for the use of onabotulinumtoxinA ic alone or in combination with PDE5-Is for difficult-to-treat ED. We thus compared the effects of BTX-A ic alone and BTX-A ic combined with PDE5-I iv, and a placebo treatment ic or iv.

METHODS

Erectile function was evaluated following cavernous nerve electrical stimulation (6 V, 1-millisecond pulse, 45-second duration) at different frequencies (0, 2, 3, 4, 5, 7.5, and 10 Hz) in 4 groups (n = 8 / group) of anesthetized, spontaneously hypertensive rats, a robust animal model of ED of vascular origin. Rats were treated by onabotulinumtoxinA 10U or saline ic 1 week prior to erectile function testing and sildenafil (0.3 mg/kg) or saline iv 4 minutes prior to testing. Frequency-response curves were compared with a 2 way ANOVA.

OUTCOMES

Both onabotulinumtoxinA ic, and sildenafil iv significantly improved erectile responses in spontaneously hypertensive rats, however the effect was greatly amplified when the treatments were combined.

RESULTS

Intracavernosal pressure and/or mean arterial pressure ratios were significantly increased by sildenafil and onabotulinumtoxinA ic versus the control condition. OnabotulinumtoxinA 10U ic combined with sildenafil iv significantly potentiated erectile responses. Area under the curve and/or mean arterial pressure ratio increased by 19% with sildenafil iv, by 15% with onabotulinumtoxinA ic and by 58% with the combined treatment following cavernous nerve electrical stimulation at 6V, 1 ms, 10 Hz: these stimulation parameters elicited the maximal erectile response.

CLINICAL TRANSLATION

These data provide a pharmacological rationale for the combined administration of onabotulinumtoxinA ic and sildenafil iv since the effects of both treatments were potentiated when their administration was combined.

STRENGTHS & LIMITATIONS

First evidence of a synergistic pro-erectile effect of BTX-A combined with PDE5-I, however the mechanism behind the pro-erectile effect of BTX-A ic remains hypothetical.

CONCLUSIONS

These results support further studies into the mechanisms behind the pro-erectile effect of BTX-A ic, as well as multicenter randomized control trials to evaluate the safety and efficacy of BTX-A ic combined with sildenafil for difficult-to-treat ED. Giuliano F., Joussain C., Denys P., et al. Intracavernosal OnabotulinumtoxinA Exerts a Synergistic Pro-Erectile Effect When Combined With Sildenafil in Spontaneously Hypertensive Rats. J Sex Med 2022;19:899-906.

Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization

Background

Low-intensity extracorporeal shock wave therapy (Li-ESWT) has been reported to improve erectile function in patients with moderate-to-severe erectile dysfunction (ED) or even convert phosphodiesterase type 5 inhibitors nonresponders to responders. ED is highly prevalent in hypertensive patients. The effect of Li-ESWT on an animal model of hypertension-associated ED has not been reported.

Aim

To investigate the effect of Li-ESWT on hypertension-associated ED and provide plausible mechanisms of action of Li-ESWT on local mechanisms of penile erection.

Methods

Spontaneously hypertensive rats (SHRs) in the active group (n = 13) received Li-ESWT at energy flux density 0.06 mJ/mm² (Aries; Dornier MedTech, Wessling, Germany) twice weekly for 6 weeks. The emitter was set to zero for SHRs in the sham group (n = 12). Erectile function was assessed 4 weeks post-treatment by monitoring intracavernosal pressure (ICP) in response to electrical stimulation of cavernous nerve before and after single dose of 0.3 mg/kg intravenous sildenafil. Cavernosal tissue was then evaluated for collagen/smooth muscle content, neuronal nitric oxide synthase (nNOS), and vascular endothelial factor (CD31) expression.

Outcomes

Erectile function was assessed with ICP, erectile tissue remodeling was studied by smooth muscle/collagen ratio, nNOS and CD31 were semiquantitatively evaluated on cavernosal sections.

Results

The improvement of ICP parameters was greater in Li-ESWT–treated rats compared with controls with and without sildenafil. Sildenafil led to 20% increase in area under the intracavernosal pressure curve measured during the entire response/mean arterial pressure at 10 Hz in ESWT_SHR + sildenafil compared with ESWT_SHR. The smooth muscle/collagen ratio increased 2.5-fold in Li-ESWT compared with sham. Expression of CD31 tended to be increased whereas nNOS was unchanged.

Conclusions

Li-ESWT by Aries may represent an effective noninvasive therapeutic alternative and a relevant add-on therapy to phosphodiesterase type 5 inhibitors for ED in hypertensive patients, and it is suggested that it acts via remodeling of the penile tissue and promoting cavernosal vascularization.

Assaly R, Giuliano F, Clement P, et al. Extracorporeal Shock Waves Therapy Delivered by Aries Improves Erectile Dysfunction in Spontaneously Hypertensive Rats Through Penile Tissue Remodeling and Neovascularization. Sex Med 2019;7:441–450

The corpus cavernosum after treatment with dutasteride or finasteride: A histomorphometric study in a benign prostatic hyperplasia rodent model

Erectile dysfunction is a common side effect of finasteride and dutasteride treatments. The objective of this study was to investigate the structural changes in the penis using a benign prostatic hyperplasia (BPH) rodent model treated with dutasteride or finasteride. Sixty male rats were divided into the following groups: C, untreated control rats; C + D, control rats receiving dutasteride; C + F, control rats receiving finasteride; H, untreated spontaneously hypertensive rats (SHRs); H + D, SHRs treated with dutasteride; and H + F, SHRs treated with finasteride. Treatments were performed for 40 days, and penises were collected immediately thereafter. The organs were analyzed using histomorphometric methods to determine the cross-sectional penile area, as well as the surface density (Sv) of smooth muscle fibers, connective tissue, elastic system fibers, and sinusoidal spaces of the corpus cavernosum. The results were compared using a one-way ANOVA with Bonferroni's posttest. Groups C + D and C + F had a significantly smaller penile cross-sectional area, but more elastic system fiber Sv compared to Group C. Group C + D showed less smooth muscle Sv, and Group H showed more connective tissue but a smaller sinusoidal space Sv in the corpus cavernosum compared to Group C. Groups H + D and H + F had less smooth muscle Sv than Group H. Group H + D also had more connective tissue and elastic system fiber Sv than Group H. Both dutasteride and finasteride promoted penile modifications in the control rat penis, although this affect was greater in Group H animals. In this rodent model, dutasteride was the drug that most affected the corpus cavernosum.

PnPP-19 Peptide Restores Erectile Function in Hypertensive and Diabetic Animals Through Intravenous and Topical Administration

INTRODUCTION

With the aim of overcoming the high toxicity of PnTx2-6 (or δ-CNTX-Pn2a), a toxin from the venom of the armed spider (Phoneutria nigriventer), the 19-aminoacid peptide, PnPP-19 (P nigriventer potentiator peptide), was synthesized based on molecular modeling studies of PnTx2-6. PnPP-19 improved the erectile function of normotensive rats and mice, without eliciting side effects, and no signs of toxicity were observed. In addition, PnPP-19 was able to potentiate the effect of sildenafil.

AIM

To evaluate the efficacy of PnPP-19 in hypertensive and diabetic mouse/rat models in restoring erectile function, after topical administration; verify the biodistribution of PnPP-19 administration (topical and intravenous), permeation, and cyclic guanosine monophosphate (cGMP)/nitric oxide via implication.

METHODS

Corpus cavernosum relaxation was evaluated using cavernous strips from male spontaneous hypertensive rats (SHR) and from streptozotocin (STZ)-diabetic mice contracted with phenylephrine and submitted to electrical field stimulation before and after incubation with PnPP-19 (10^-8 mol/L, 10 minutes) or vehicle. This procedure was also used to determine cGMP/nitric oxide levels, at 8 Hz and to check the effect of PnPP-19 with sildenafil citrate. Biodistribution assays were performed using iodine 123-radiolabeled PnPP-19. In vivo erectile function was evaluated using intracavernosal pressure/main arterial pressure ratio in STZ-diabetic rats after PnPP-19 topical administration.

MAIN OUTCOME MEASURES

PnPP-19 may become a new drug able to fill the gap in the pharmacologic treatment of erectile dysfunction, especially for hypertensive and diabetic individuals RESULTS: PnPP-19 potentiated corpus cavernosum relaxation, in both control and SHR rats. SHR-cavernosal tissue treated with PnPP-19 (1-32 Hz) reached the same relaxation levels as control Wistar rats (16 and 32 Hz). PnPP-19 treatment improved cavernosal tissue relaxation in STZ-diabetic mice and rats. PnPP-19 enhanced cGMP levels in STZ-diabetic mice corpus cavernosum strips. After topical or intravenous administration in rats, ¹²³I-PnPP-19 was mainly recruited to the penis. When topically administered (400 μg/rat), PnPP-19 restores erectile function in STZ-diabetic rats, also improving it in healthy rats by increasing the intracavernosal pressure/main arterial pressure ratio. PnPP-19 exhibited an additive effect when co-administered with sildenafil, showing a novel mode of action regardless of phosphodiesterase type 5 inhibition.

CLINICAL IMPLICATIONS

PnPP-19 seems to be an indicated drug to be tested to treat ED in diabetic and hypertensive patients.

STRENGTH & LIMITATIONS

PnPP-19, although active by topical application and showing safety to human beings (not shown), has low permeability, about 10% of the applied dose.

CONCLUSION

Our results showed that PnPP-19 may emerge as a potent new drug that can be topically administered, becoming a promising alternative for erectile dysfunction treatment. Nunes da Silva C, Pedrosa Nunes K, De Marco Almeida F, et al. PnPP-19 Peptide Restores Erectile Function In Hypertensive And Diabetic Animals Through Intravenous And Topical Administration. J Sex Med 2019;16:365-374.

Erectile Dysfunction and Ischaemic Heart Disease

Erectile dysfunction (ED) is a common disorder that affects the quality of life of many patients. It is prevalent in more than half of males aged over 60 years. Increasing evidence suggests that ED is predominantly a vascular disorder. Endothelial dysfunction seems to be the common pathological process causing ED. Many common risk factors for atherosclerosis such as diabetes, hypertension, smoking, obesity and hyperlipidaemia are prevalent in patients with ED and so management of these common cardiovascular risk factors can potentially prevent ED. Phosphodiesterase type 5 inhibitors provide short-term change of haemodynamic factors to help initiate and maintain penile erection. They have been shown to be an effective and safe treatment strategy for ED in patients with heart disease, including those with ischaemic heart disease and hypertension.

Erectile Dysfunction and Lower Urinary Tract Symptoms

CONTEXT

Lower urinary tract symptoms (LUTSs) and erectile dysfunction (ED) are substantial health concerns with a significant impact on the overall male quality of life.

OBJECTIVE

To evaluate the available evidence of the association between LUTSs and ED in patients with benign prostatic hyperplasia (BPH), and discuss possible clinical implications for the management of LUTS/BPH.

EVIDENCE ACQUISITION

A systematic review of the existing literature published between 1997 and June 2017 and available in the Medline, Scopus, and Web of Science databases was conducted using both the Medical Subject Heading (MeSH) and free-text protocols. The MeSH search was conducted by combining the following terms: "lower urinary tract symptoms," "LUTS," "benign prostatic hyperplasia," "BPH," "erectile dysfunction," "sexual dysfunction," "BPE," and "benign prostatic enlargement." The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed.

EVIDENCE SYNTHESIS

Several community-based studies in different geographical areas have provided strong evidence of an age-independent association between LUTSs and ED. Several biological mechanisms have been proposed to explain this association, but further research is required to better understand the molecular pathways involved. It is necessary to evaluate the possible impact of the metabolic syndrome treatment on LUTS/ED management. Considering the possible relationship between LUTSs and ED, their impact on the quality of life, and the possible adverse effects associated with LUTS medical treatment, clinicians should always evaluate ED in patients with LUTSs and take the opportunity to evaluate patients reporting ED for LUTSs.

CONCLUSIONS

Data from the peer-reviewed literature suggest the existence of an association between LUTS/BPH and ED, although their casual relationship has not been established yet. Emerging data also suggest that pathophysiological mechanisms involved in the metabolic syndrome are key factors in both disorders. Considering the association, it is also recommended that men presenting with LUTSs or ED should be evaluated for both disorders. A better understanding of the molecular pathways behind this association may also help identify new possible targets and develop novel therapeutic approaches to manage LUTSs and ED.

PATIENT SUMMARY

In this manuscript, we report on all the available evidence linking erectile dysfunction and lower urinary tract symptoms. Our findings suggest the existence of a strong relationship between these two conditions. On the basis of these findings, we recommend that clinicians always explore both conditions in male patients presenting with either of symptoms.

Effects of Root Extracts of Eurycoma longifolia Jack on Corpus Cavernosum of Rat

OBJECTIVE

This study was conducted to investigate the mechanisms of action of Eurycoma longifolia in rat corpus cavernosum.

MATERIALS AND METHODS

Tincture of the roots was concentrated to dryness by evaporating the ethanol in vacuo. This ethanolic extract was partitioned into 5 fractions sequentially with hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The corpus cavernosum relaxant activity of each fraction was investigated. The DCM fraction which showed the highest potency in relaxing phenylephrine-precontracted corpora cavernosa was purified by column chromatography. The effects of the most potent DCM subfraction in relaxing phenylephrine-precontracted corpora cavernosa, DCM-I, on angiotensin I- or angiotensin II-induced contractions in corpora cavernosa were investigated. The effects of DCM-I pretreatment on the responses of phenylephrine-precontracted corpora cavernosa to angiotensin II or bradykinin were also studied. An in vitro assay was conducted to evaluate the effect of DCM-I on angiotensin-converting enzyme activity.

RESULTS

Fraction DCM-I decreased the maximal contractions (100%) evoked by angiotensin I and angiotensin II to 30 ± 14% and 26 ± 16% (p < 0.001), respectively. In phenylephrine-precontracted corpora cavernosa, DCM-I pretreatment caused angiotensin II to induce 82 ± 27% relaxation of maximal contraction (p < 0.01) and enhanced (p < 0.001) bradykinin-induced relaxations from 47 ± 8% to 100 ± 5%. In vitro, DCM-I was able to reduce (p < 0.001) the maximal angiotensin-converting enzyme activity to 78 ± 0.24%.

CONCLUSION

Fraction DCM-I was able to antagonize angiotensin II-induced contraction to cause corpus cavernosum relaxation via inhibition of angiotensin II type 1 receptor and enhance bradykinin-induced relaxation through inhibition of angiotensin-converting enzyme.

eNOS Function and Dysfunction in the Penis

Endothelial nitric oxide (NO) synthase (eNOS) has an indispensable role in the erectile response. In the penis, eNOS activity and endothelial NO bioavailability are regulated by multiple post-translatlonal molecular mechanisms, such as eNOS phosphorylation, eNOS interaction with regulatory proteins and contractile pathways, and actions of reactive oxygen species (ROS). These mechanisms regulate eNOS-mediated responses under physiologic circumstances and provide various mechanisms whereby endothelial NO availability may be altered in states of vasculogenlc erectile dysfunction (ED), in view of the recent advances in the field of eNOS function in the penis and its role in penile erection, the emphasis in this review is placed on the mechanisms regulating eNOS activity and its interaction with the RhoA/Rho-kinase pathway in the physiology of penile erection and the pathophysiology of ED.

An experimental study: evaluating the tissue structure of penis with 2D-ShearWave™ Elastography

The aim of this study was to investigate the feasibility of two-dimensional-ShearWave™ Elastography (2D-SWE) on evaluating the change of tissue structure of penis. Twenty healthy male Sprague Dawley rats were divided into penis-developed group (PDG, 52 weeks) and penis-underdeveloped group (PUDG, 5 weeks). The ultrafast ultrasound device-Aixplorer® (SuperSonic Imagine) was used for 2D-SWE imaging of the penis, the measurement index was shear wave stiffness (SWS, kPa). All rat penises were cut off immediately after ultrasonic examination. After paraffin embedding, slicing and hematoxylin-eosin staining, the tissue structure of the penis was observed under light microscope. SWS of all rat penises were measured successfully. The results showed that SWS of PDG was significantly lower than PUDG (P=0.008). At the same time, the pathological results found that there were significant differences in the tissue structures (sinusoids, smooth muscle cells and fibrocytes) of the penises between the two groups. These results suggest that there are significant differences in SWS between different tissue structures of penis. 2D-SWE is expected to be used on the etiological diagnosis of erectile dysfunction by serving as a new noninvasive method of evaluating the change of tissue structure of penis.

Animal models of erectile dysfunction

Erectile dysfunction (ED) is a prevalent male sexual dysfunction with profound adverse effects on the physical and the psychosocial health of men and, subsequently, on their partners. The expanded use of various types of rodent models has produced some advances in the study of ED, and neurophysiological studies using various animal models have provided important insights into human sexual dysfunction. At present, animal models play a key role in exploring and screening novel drugs designed to treat ED.

Effect of an angiotensin II receptor blocker and a calcium channel blocker on hypertension associated penile dysfunction in a rat model

Possible effect of olmesartan, an angiotensin II receptor blocker (ARB), or nifedipine, an L-type calcium channel blocker, on penile dysfunction in the spontaneously hypertensive rat (SHR) was investigated in this study. Twelve-week-old male SHRs were treated with olmesartan (1 or 3 mg/kg, per orally (p.o.)) or nifedipine (30 mg/kg, p.o.) once a day for 6 weeks. Wistar rats and SHRs with vehicle treatment were used as controls. Penile cGMP and malondialdehyde concentrations, and mRNA levels of endothelial and neuronal NO synthase (eNOS and nNOS) were measured. Penile function was evaluated by organ bath studies with norepinephrine-induced contractions and acetylcholine-induced relaxations. The SHR showed significantly increased blood pressure, decreased cGMP concentrations, increased malondialdehyde concentrations, decreased eNOS and nNOS mRNA levels, norepinephrine-induced hyper-contractions, and acetylcholine-induced hypo-relaxations in the penile tissue compared to the Wistar rat. Both nifedipine and olmesartan significantly decreased blood pressure, increased cGMP and normalized the hyper-contractions and hypo-relaxations observed in the SHR group. However, not nifedipine but olmesartan improved the malondialdehyde concentrations and increased mRNA levels of eNOS and nNOS in the penis. Our results indicate that the hypertension-associated penile dysfunction might be treated with ARBs such as olmesartan better than calcium channel blockers, such as nifedipine.

Hydroxyfasudil ameliorates penile dysfunction in the male spontaneously hypertensive rat

Hypertension represents a major risk factor for erectile dysfunction. Although the etiology of hypertension-induced erectile dysfunction is multifactorial and still unknown, Rho-Rho kinase pathway is one of the key factors. To investigate whether administration of hydroxyfasudil, a Rho kinase inhibitor could prevent dysfunction of NO-induced relaxation in corpus cavernosum smooth muscle in the SHR (spontaneously hypertensive rat), twelve-week-old male SHRs were treated with hydroxyfasudil (3 or 10 mg/kg, i.p.) once a day for 6 weeks. Wistar rats and SHRs treatment with vehicle were used as age-matched controls. Penile cGMP concentrations and Rho kinase activities were determined, and penile function was estimated by organ bath studies with norepinephrine-induced contractions and acetylcholine-induced relaxations. The participation mRNA levels of eNOS and participation protein levels of eNOS and phosphorylated eNOS were investigated by quantitative real-time PCR methods and immunoblot analysis, respectively. The SHR showed significantly decreased cGMP concentrations, increased Rho kinase activities, norepinephrine-induced hyper-contractions, and acetylcholine-induced hypo-relaxations in the penile tissue. Treatment with hydroxyfasudil significantly improved the decreased penile cGMP concentrations, the increased Rho kinase activities, the increased norepinephrine-induced contractions, and the decreased acetylcholine-induced relaxation in a dose-dependent manner. Although there were no significant differences in expression protein levels of eNOS among any of the groups, down-regulation of eNOS mRNAs as well as phosphorylated eNOS were significantly ameliorated after treatment with hydroxyfasudil. Our data suggest that hydroxyfasudil ameliorates hypertension-associated dysfunction of NO-induced relaxation in corpus cavernosum smooth muscle possibly via inhibition of the Rho-Rho kinase pathway and activation of NO-eNOS pathway in the SHR.

HDAC4 mediates development of hypertension via vascular inflammation in spontaneous hypertensive rats

Histone deacetylases (HDACs) are transcriptional corepressors. Our recent study demonstrated that HDAC4 protein specifically increases in mesenteric artery from spontaneous hypertensive rats (SHR) compared with Wistar Kyoto rats (WKY). Vascular inflammation is important for pathogenesis of hypertension. We examined whether HDAC4 affects vascular inflammatory responses and promotes hypertension. In vivo, blood pressure, reactive oxygen species (ROS) production, and VCAM-1 expression in isolated mesenteric artery were elevated in young SHR (7 wk old) compared with age-matched WKY, which were prevented by long-term treatment of SHR with an HDACs inhibitor, trichostatin A (TSA; 500 μg·kg−1·day−1 for 3 wk). In isolated mesenteric artery, the increased angiotensin II-induced contraction in SHR was reversed by TSA. The endothelium-dependent relaxation induced by ACh in SHR was augmented by TSA. In cultured rat mesenteric arterial smooth muscle cells (SMCs), expression of HDAC4 mRNA and protein was increased by TNF-α (10 ng/ml). TSA (10 μM, pretreatment for 30 min) inhibited VCAM-1 expression and NF-κB phosphorylation induced by TNF (10 ng/ml, 24 h or 20 min) in SMCs. HDAC4 small interfering RNA inhibited TNF-induced monocyte adhesion, VCAM-1 expression, transcriptional activity of NF-κB, and ROS production in SMCs. The present results demonstrated that proinflammatory effects of HDACs may mediate the further development of hypertension in SHR. It is also suggested in cultured vascular SMCs that TNF-induced HDAC4 mediates vascular inflammation likely via VCAM-1 induction through ROS-dependent NF-κB activation.

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

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

Current benign prostatic hyperplasia treatment: impact on sexual function and management of related sexual adverse events

Benign prostatic hyperplasia (BPH) is a common disease in older men that can lead to lower urinary tract symptoms (LUTS). Male sexual dysfunction is also an age-related condition. Epidemiological studies have confirmed an association between BPH/LUTS and sexual dysfunction in ageing men that is independent of the effects of age, other co-morbidities and lifestyle factors. Proposed pathophysiological mechanisms for BPH/LUTS-associated sexual dysfunction include the nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway, rho-kinase and endothelin-1 activity, autonomic nervous system overactivity and the metabolic syndrome, and pelvic organ atherosclerosis. Both BPH/LUTS and sexual dysfunction can have a substantial negative impact on a man's quality of life. However, urologists and primary care physicians appear to under-recognise sexual dysfunction in men with BPH/LUTS. Current guidelines recommend alpha-blockers and 5-alpha reductase inhibitors, either alone or in combination, among appropriate medical treatment options for BPH/LUTS. Randomised, controlled trials demonstrate that these therapies can be associated with sexual adverse effects (AEs) such as loss of libido, erectile dysfunction and ejaculatory disorders. Sexual dysfunction should be fully evaluated in men requiring treatment for BPH/LUTS using validated questionnaires. Management of sexual dysfunction in men treated for BPH/LUTS should involve assessment of co-morbidities and concomitant medications, consideration of lifestyle interventions such as weight loss and increased physical activity to improve risk factors and, if necessary, introduction of pharmacotherapies. In addition, physicians should provide patients with proper counselling on the possible sexual AEs of medical therapies for BPH/LUTS and their impact on sexual satisfaction, while being aware of the possibility that counselling in itself is likely to influence reported rates of sexual dysfunction.

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.

Anatomy, physiology, and pathophysiology of erectile dysfunction

INTRODUCTION

Significant scientific advances during the past 3 decades have deepened our understanding of the physiology and pathophysiology of penile erection. A critical evaluation of the current state of knowledge is essential to provide perspective for future research and development of new therapies.

AIM

To develop an evidence-based, state-of-the-art consensus report on the anatomy, physiology, and pathophysiology of erectile dysfunction (ED).

METHODS

Consensus process over a period of 16 months, representing the opinions of 12 experts from seven countries.

MAIN OUTCOME MEASURE

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

RESULTS

ED occurs from multifaceted, complex mechanisms that can involve disruptions in neural, vascular, and hormonal signaling. Research on central neural regulation of penile erection is progressing rapidly with the identification of key neurotransmitters and the association of neural structures with both spinal and supraspinal pathways that regulate sexual function. In parallel to advances in cardiovascular physiology, the most extensive efforts in the physiology of penile erection have focused on elucidating mechanisms that regulate the functions of the endothelium and vascular smooth muscle of the corpus cavernosum. Major health concerns such as atherosclerosis, hyperlipidemia, hypertension, diabetes, and metabolic syndrome (MetS) have become well integrated into the investigation of ED.

CONCLUSIONS

Despite the efficacy of current therapies, they remain insufficient to address growing patient populations, such as those with diabetes and MetS. In addition, increasing awareness of the adverse side effects of commonly prescribed medications on sexual function provides a rationale for developing new treatment strategies that minimize the likelihood of causing sexual dysfunction. Many basic questions with regard to erectile function remain unanswered and further laboratory and clinical studies are necessary.

Beneficial impact of exercise and obesity interventions on erectile function and its risk factors

INTRODUCTION

Erectile dysfunction (ED) is a multifaceted disease involving cardiovascular, metabolic, and hormonal factors and affects over 100 million men worldwide. ED has been shown to be a harbinger of underlying cardiovascular diseases (CVD), as there are common risk factors (aging, hypertension, obesity) and mechanistic basis.

AIM

To provide an update on clinical and experimental evidence regarding the impact of lifestyle modifications, such as exercise and diet, with respect to changes in erectile function.

MAIN OUTCOME MEASURES

Published evidence regarding the impact of aging, hypertension, and obesity on ED and CVD, as well as new experimental data linking obesity and diminished erectile responses.

METHODS

We reviewed the literature regarding common risk factors of ED and CVD, particularly involving obesity, as well as performed new analysis on the findings of other experimental studies involving diet and exercise interventions.

RESULTS

Physical inactivity negatively impacts on erectile function, and experimental and clinical exercise interventions have been shown to improve sexual responses and overall cardiovascular health. Mediterranean-style diets and a reduction in caloric intake have been found to improve erectile function in men with the aspects of the metabolic syndrome. In addition, both clinical and experimental studies have confirmed that combining the two interventions provides additional benefit to erectile function, likely via reduced metabolic disturbances (e.g., inflammatory markers, insulin resistance), decreased visceral adipose tissue, and improvement in vascular function (e.g., increased endothelial function).

CONCLUSIONS

Lifestyle modifications provide significant benefits to vascular health and erectile function in a population that is increasingly aged and more obese.

The endothelial-erectile dysfunction connection: an essential update

INTRODUCTION

The endothelial monolayer plays a crucial role in the vasodilation and hemodynamic events involved in erection physiology. Due to its relevant functions, a close link has been established between endothelial integrity and erectile dysfunction (ED). Endothelial dysfunction is induced by the detrimental actions of vascular risk factors (VRFs), identified as common correlates for the development of cardiovascular disease and ED. It is currently recognized that ED is the early harbinger of a more generalized vascular systemic disorder, and, therefore, an evaluation of endothelial health in ED patients should be of prime relevance. Several noninvasive methods for endothelial function assessment have been proposed, including the Penile Nitric Oxide Release Test (PNORT).

AIM

To highlight the most recent gathered knowledge on basic and clinical mechanisms underlying loss of cavernosal endothelial function promoted by VRFs and to discuss local and systemic methods for endothelial function assessment in ED individuals, focusing on the PNORT.

MAIN OUTCOME MEASURES

A complete revision on the novel basic and clinical links between endothelial and ED.

METHODS

A systematic review of the literature regarding the aforementioned issues.

RESULTS

Risk factor-associated cavernosal endothelial dysfunction is mostly induced by unifying mechanisms, including oxidative stress and impaired endothelial nitric oxide functional activities, which present clinically as ED. Several techniques to evaluate endothelial dysfunction were revised, with advantages and limitations debated, focusing on our detailed expertise using the PNORT method.

CONCLUSIONS

The established endothelial-erectile dysfunction connection was thoroughly revised, from basic mechanisms to the clinical importance of endothelial dysfunction assessment as diagnosis for generalized vascular disease. Further studies are required to disclose efficient approaches to repair disabled endothelium and both restore and prevent endothelial dysfunction.

Elevation of intracavernous pressure and NO-cGMP activity by a new herbal formula in penile tissues of spontaneous hypertensive male rats

AIM OF THE STUDY

We created a new herbal formulation that mainly consists of the seeds of Lycium chinense, Cornus officinalis, Rubus coreanus, Cuscuta chinensis and Schizandra chinensis. These materials have been long used by Korean people as they are known to be good for health and sexual function; hence we could say that their safety have been proven in a certain sense. We investigated the effects of this herbal formulation on the penile erection and corpus cavernosum of spontaneous hypertensive male Rats (SHRs).

MATERIALS AND METHODS

We used male SHRs aged 16 weeks as a model of hypertension. The treatment groups received once a day oral doses of KH-204 at either 100 or 300mg/kg per day for 4 weeks. Distilled water was administered to the control group. To investigate the penile erection, the intracavernosal pressure (ICP) and mean arterial pressure (MAP) were recorded in all groups. We analyzed the distribution of NOS by immunohistochemical staining and the expressions of nNOS and eNOS in the isolated corpus cavernosum were measured by Western blotting.

RESULTS

In the control group, the ICP/MAP ratio was 14.9+/-1.4% after pelvic nerve stimulation. The ICP/MAP ratio was markedly increased in the treatment group with KH-204 100 or 300mg/kg, compared with the control group. Immunohistochemical staining for NOS showed that eNOS and nNOS were stained as a brown color. Compared with the control group, the NOS activities of KH-204 100 or 300mg/kg were significantly increased. Also, the penile expression levels of nNOS and eNOS in the KH-204 100 and 300mg/kg treatment groups were more increased, and this was significant, than those of the control group, as was determined by Western blotting.

CONCLUSIONS

This study showed that the KH-204 herbal formulation enhances intracavernous pressure and NO-cGMP activity in penile tissues of SHR male rats.

Sexual dysfunction: the 'prima ballerina' of hypertension-related quality-of-life complications

Sexual dysfunction is currently considered a serious quality-of-life-related health problem, exerting a major impact on patients' and their sexual partners' life. Available data indicate that essential hypertension is a risk factor for sexual dysfunction, as male and female sexual dysfunction is more prevalent in hypertensive patients than normotensive individuals. Several mechanisms have been implicated in the pathogenesis of sexual dysfunction in hypertensive patients, and major determinants include severity and duration of hypertension, age, and antihypertensive therapy. Female sexual dysfunction, although more frequent than its male counterpart, remains largely under-recognized. Older antihypertensive drugs (diuretics, beta-blockers, centrally acting) exert negative results, whereas newer drugs have either neutral (calcium antagonists, angiotensin-converting enzyme inhibitors) or beneficial effects (angiotensin receptor blockers). Erectile dysfunction is related to ischemic heart disease and might be an 'early therapeutic window' of asymptomatic coronary artery disease. It seems of utmost importance for every physician treating hypertensive patients to become familiar with sexual dysfunction (through better education and specific seminars) for the proper management of these patients.

NADPH oxidase: recent evidence for its role in erectile dysfunction

Important roles for reactive oxygen species (ROS) in physiology and pathophysiology have been increasingly recognized. Under normal conditions, ROS serve as signaling molecules in the regulation of cellular functions. However, enhanced ROS production as a result of the activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase contributes significantly to the pathogeneses of vascular diseases. Although it has become evident that increased ROS is associated with erectile dysfunction (ED), the sources of ROS in the penis remain largely unknown. In recent years, emergent evidence suggests the possible role of NADPH oxidase in inducing ED. In this review, we examine the relationship between ROS and ED in different disease models and discuss the current evidence basis for NADPH oxidase-derived ROS in ED.

Identifying patients with benign prostatic hyperplasia through a diagnosis of, or treatment for, erectile dysfunction

OBJECTIVE

Erectile dysfunction (ED) and lower urinary tract symptoms (LUTS) associated with benign prostate hyperplasia (BPH) are highly correlated. This study examined rates of screening, diagnosis, and treatment of BPH/LUTS among men seeking care for ED.

RESEARCH DESIGN AND METHODS

This was a retrospective US claims data analysis (1999-2004) evaluating men > or = 40 years old with a new diagnosis of or prescription medication for ED. Multivariate analyses were used to examine times to screening, diagnosis, and treatment.

RESULTS

81 659 men with ED were identified (mean age 57 years). The baseline prevalence of recorded BPH was 1.5%. During the follow-up period (mean 2.2 years), 7.6% had documented BPH. Time to screening was shorter among patients seeing urologists (121.1 days) compared with those seeing primary-care physicians (282.2 days). Controlling for demographic and clinical characteristics, patients who saw a urologist were more likely to be screened (OR: 2.4, p < 0.0001), diagnosed with BPH (OR: 1.8, p < 0.0001), and treated (OR: 1.3, p < 0.0001), relative to patients seeing other providers. Men aged 75 and over were 43% less likely to be screened (p < 0.0001), but 5.4 times more likely to be diagnosed with BPH (p < 0.0001) and 5.3 times more likely to be treated (p < 0.0001) compared with men aged 40-49.

CONCLUSIONS

Screening for BPH appears less likely for men with ED who do not see a urologist. When screening does occur, it takes much longer with non-specialty providers. Patient age and provider specialty are key factors associated with screening, diagnosis, and treatment of BPH among men with ED.

Recovery of erectile function in aging hypertensive and normotensive rats using exercise and caloric restriction

INTRODUCTION

Using aging spontaneously hypertensive rats (SHR), we established that antihypertensive drugs can improve erections and penile vascular structure, and lower arterial pressure. Using kidney cross-transplantations, our findings revealed that the benefit of this treatment resulted from drug-induced changes specific to the penile circulation, and not to the kidney-mediated lowering of pressure.

AIM

The objective of the present study was to determine whether increased exercise and/or caloric restriction (CR) can reverse the decline in sexual responses in aging hypertensive and normotensive rats.

METHODS

From 30 to 40 weeks, food intake was restricted (10-40%), and SHR, Wistar, and Sprague-Dawley rats ran on treadmills (30 minutes/day, 5 days/week). Exercise was withdrawn at 40 weeks, and CR was stopped at 50 weeks. Using a separate group of older Wistars (56 weeks) and Sprague-Dawley rats (67 weeks), the effects of 10% CR or exercise plus 10-40% CR on erectile function were determined.

MAIN OUTCOME MEASURE

Apomorphine-induced erectile responses and body weight were monitored weekly.

RESULTS

An age-related decline in erections was seen from 15 to 29 weeks of age in all strains. This decline paralleled increases in body weight, particularly in the normotensive strains. Exercise and CR induced a 10% weight loss in normotensive rats and improved erections in all animals. In SHR, increased erections occurred without decreasing body weight. Body weight and erectile responses were maintained by CR alone after exercise was withdrawn, but erectile function rapidly declined soon after CR was stopped and paralleled increases in body weight. In aged Wistar and Sprague-Dawley rats treated with exercise and CR, erectile function was also significantly improved.

CONCLUSIONS

Similar to previous studies, erectile function progressively decreased with age in both hypertensive and normotensive rats. Erectile responses were found to be substantially improved by an intervention involving exercise and CR, but not necessarily involving weight loss.

Effects of ACE inhibition and beta-blockade on female genital structures in spontaneously hypertensive rats

INTRODUCTION AND AIM

This study evaluated the possible differences between an angiotensin converting enzyme (ACE) inhibitor and a beta-blocker concerning their potential protective role on female external genitalia in spontaneously hypertensive rats (SHR).

MAIN OUTCOME MEASURES

Morphological changes in the clitoris after antihypertensive treatments.

METHODS

For 6 months, SHR received no treatment; SHR + ramipril (RAM), SHR + atenolol (AT), and control Wistar Kyoto (WKY) rats received no treatment. Clitorises were processed for immunohistochemistry using anti-alpha-smooth muscle actin (alpha-SMA), anti-collagen I and III, anti-transforming growth factor beta(1) (TGFbeta(1)), and anti-endothelial nitric oxide synthase (eNOS) antibodies.

RESULTS

SHR + RAM and SHR + AT presented significantly lower blood pressure in both groups vs. untreated SHR. Compared with WKY, alpha-SMA was increased in the arteries and in the cavernous spaces of the clitoris together with a marked increase in wall/lumen ratio in clitoral vessels in untreated SHR. All these alterations were diminished in SHR + AT (P < 0.01). SHR + RAM presented differences with respect to SHR + AT in the reduction of these variables. TGFbeta(1) expression in the vessel wall from the clitoris and collagen I and III deposition in the interstitium from the clitoris in untreated SHR were significantly more (P < 0.01) than in WKY. While SHR + AT showed a mild decrease in these variables, SHR + RAM presented a significant reduction (P < 0.01) in TGFbeta(1) expression interstitial fibrosis and in both types of collagens. Positive immunostaining of eNOS in the sinusoidal endothelium from the clitoris was less (P < 0.01) in untreated SHR (3.4 +/- 1.3%) and SHR + AT (5.1 +/- 1.2%) than in SHR + RAM (17.2 +/- 1.6%) and WKY (15.9 +/- 1.7%). Untreated SHR and SHR + AT presented more surrounding connective tissue at the perineurium in the clitoris (P < 0.01) than SHR + RAM.

CONCLUSION

ACE inhibition provided a considerable protective role on the female external genitalia structures in SHR by a mechanism that may be, at least in part, independent of the degree of blood pressure lowering.

Functional and Morphological Improvement in Erectile Tissue of Hypertensive Rats by Long-Term Combined Therapy with Phosphodiesterase Type 5 Inhibitor and Losartan

INTRODUCTION

Erectile dysfunction (ED) is highly associated to cardiovascular disease, especially arterial hypertension. Phosphodiesterase type 5 (PDE5) inhibitors and angiotensin II receptor blockers (ARB) are both common and efficient therapy in patients with ED and arterial hypertension, respectively.

AIM

To evaluate the effect of PDE5 inhibitor, sildenafil (S), and of ARB Losartan (L) in a continuous combined therapy for a long term on penile structures in a hypertensive rat model.

METHODS

During 6 months, four groups of male spontaneously hypertensive rats (SHR) and one of Wistar-Kyoto (WKY) rats, as control group, were studied: no-treatment SHR, SHR with L, SHR with S, SHR with S + L, and no-treatment WKY. Cavernous smooth muscle (CSM) and vascular smooth muscle (VSM) from cavernous arteries, collagen type III (COL-III), and endothelial nitric oxide synthase (eNOS) expression in cavernous space were evaluated.

MAIN OUTCOME MEASURE

Functional and morphological differences between S and L in a continuous combined therapy vs. either drug as monotherapy on penile structures.

RESULTS

After 6 months, SHR that received L, S, or combined therapy showed a similar reduction in blood pressure compared with untreated SHR. Nevertheless, SHR + L + S and control WKY showed significantly lower values of (i) CSM (P < 0.01), (ii) VSM (P < 0.01), and (iii) COL-III (P < 0.01) when compared with the untreated SHR and also with the SHR with monotherapy. Additionally, SHR + L + S, presented a higher eNOS expression in sinusoidal endothelium in comparison with the untreated SHR and the SHR with monotherapy (P < 0.01). In vitro studies revealed that SHR + L + S displayed a better relaxation response to acetylcholine than the untreated SHR and the SHR with monotherapy (P < 0.01).

CONCLUSION

These results suggest that a long-term combined therapy using L and S is a useful tool for functional and structural modification in cavernous tissue from SHR.

Physiological regulation of penile arteries and veins

Recent experimental evidence suggests that arterial insufficiency precedes the structural and functional changes in corpora cavernosa (CC) leading to organic erectile dysfunction (ED). The present review gives an overview of the physiological factors involved in the regulation of penile vasculature. Sympathetic nerves maintain flaccidity and tonically released noradrenaline induces vasoconstriction of both arteries and veins through alpha(1)- and alpha(2)-postsynaptic receptors and downregulates its own release and that of nitric oxide (NO) through alpha(2)-presynaptic receptors. The sympathetic cotransmitter neuropeptide Y (NPY) modulates noradrenergic vasoconstriction in penile small arteries by both enhancing and depressing noradrenaline contractions through Y(1)- and Y(2)-postsynaptic and a NO-independent atypical endothelial receptor, respectively. Activation of alpha(1)-adrenoceptors involves both Ca(2+) influx through L-type and receptor-operated Ca(2+) channels (ROC) and Ca(2+) sensitization mechanisms mediated by protein kinase C (PKC), tyrosine kinases (TKs) and Rho kinase (RhoK). In addition, RhoK can regulate Ca(2+) entry in penile arteries upon receptor stimulation. Vasodilatation of penile arteries and large veins during erection is mediated by neurally released NO. The subsequent increased arterial inflow to the cavernosal sinoids and shear stress on the endothelium lining penile arteries activates endothelial NO production through Akt phosphorylation of endothelial NO synthase (eNOS). NO stimulates guanylate cyclase and increased cyclic guanin 3'-monophosphate (cGMP) levels in turn activate protein kinase G (PKG), which enhances K(+) efflux through Ca(2+)-activated (K(Ca)) and voltage-dependent Ca(2+) (K(v)) channels in penile arteries and veins, respectively. PKG-mediated decrease in Ca(2+) sensitivity and its regulation by RhoK remains to be clarified in penile vasculature. Phosphodiesterase type 5 (PDE5) inhibitors are potent vasodilators of penile resistance arteries and increase the content and effects of basally released endothelial NO. Endothelium-dependent relaxations of penile small arteries also include an endothelium-derived hyperpolarizing factor (EDHF)-type response, which is impaired in diabetes and hypertension-associated ED. Locally produced contractile and relaxant prostanoids regulate penile venous and arterial tone, respectively. The latter activates prostaglandin I (IP) and prostaglandin E (EP) receptors coupled to adenylate cyclase and to the increase of cyclic adenosine monophosphate (cAMP) levels, which in turn stimulates K(+) efflux through ATP-sensitive K(+) (K(ATP)) channels. There is a crosstalk between the cGMP and cAMP signaling pathways in penile small arteries. Relevant issues such as the mechanisms underlying the excitation-secretion coupling of the endothelial cells, as well as those involved in cell proliferation and vascular remodeling of the penile vasculature remain to be elucidated. In addition, only few studies have investigated the changes in structure and function of penile arteries in cardiovascular risk situations leading to ED.

Progesterone reduces erectile dysfunction in sleep-deprived spontaneously hypertensive rats

BACKGROUND

Paradoxical sleep deprivation (PSD) associated with cocaine has been shown to enhance genital reflexes (penile erection-PE and ejaculation-EJ) in Wistar rats. Since hypertension predisposes males to erectile dysfunction, the aim of the present study was to investigate the effects of PSD on genital reflexes in the spontaneously hypertensive rat (SHR) compared to the Wistar strain. We also extended our study to examine how PSD affect steroid hormone concentrations involved in genital events in both experimental models.

METHODS

The first experiment investigated the effects of PSD on genital reflexes of Wistar and SHR rats challenged by saline and cocaine (n = 10/group). To further examine the impact of the PSD on concentrations of sexual hormones, we performed a hormonal analysis of testosterone and progesterone in the Wistar and in SHR strains. Since after PSD progesterone concentrations decreased in the SHR compared to the Wistar PSD group we extended our study by investigating whether progesterone (25 mg/kg or 50 mg/kg) or testosterone (0.5 mg/kg or 1.0 mg/kg) administration during PSD would have a facilitator effect on the occurrence of genital reflexes in this hypertensive strain.

RESULTS

A 4-day period of PSD induced PE in 50% of the Wistar rats against 10% for the SHR. These genital reflexes was potentiated by cocaine in Wistar rats whereas this scenario did not promote significant enhancement in PE and EJ in hypertensive rats, and the percentage of SHR displaying genital reflexes still figured significantly lower than that of the Wistar strain. As for hormone concentrations, both sleep-deprived Wistar and SHR showed lower testosterone concentrations than their respective controls. Sleep deprivation promoted an increase in concentrations of progesterone in Wistar rats, whereas no significant alterations were found after PSD in the SHR strain, which did not present enhancement in erectile responses. In order to explore the role of progesterone in the occurrence of genital reflexes, SHR were treated daily during the sleep deprivation period with progesterone; after the administration of this hormone and challenge with cocaine, we observed a significant increase in erectile events compared with the vehicle PSD SHR+cocaine group.

CONCLUSION

Our data showed that the low frequency of genital reflexes found in SHR sleep deprived rats may be attributed to the lower concentrations of progesterone in these rats, based on the observation that progesterone replacement increased genital reflexes in this strain.

New Unstable Bladder Model in Hypercholesterolemia Rats

OBJECTIVES

To evaluate the voiding function of the new vasculogenic erectile dysfunction (ED) model in hypercholesterolemic rats.

METHODS

We used 14 adult 12-week-old male Sprague-Dawley rats. The cholesterol group received a 1% cholesterol diet for 8 weeks. During the initial 2 weeks, they also drank water containing 3 mg/mL of NG-nitro-L-arginine methyl ester. After 8 weeks, we performed cystometrography, a detrusor strip contraction study, and pathologic examination of the detrusor to confirm voiding dysfunction. The results of the cholesterol and control groups were compared.

RESULTS

Compared with the control group values, the mean serum cholesterol and body weight were significantly elevated in the cholesterol group. The cholesterol group had shorter voiding intervals (377.6 +/- 205.4 versus 121.8 +/- 79.6 seconds, P <0.01) and a smaller functional bladder volume (1.4 +/- 0.7 versus 0.7 +/- 0.3 mL, P <0.05) on cystometrography compared with the control group. In the detrusor strip study, the cholesterol group had greater tension in spontaneous activities and an increase (13.1% +/- 5.6% versus 28.4% +/- 16.2%, P <0.05) in the proportion of purinergic components.

CONCLUSIONS

This vasculogenic ED rat model showed significantly frequent voiding on cystometrography. Considering the many epidemiologic and experimental data, in addition to the data from this model, ED and overactive bladder could share similar pathophysiologic features or be two symptoms of a systemic disorder. This rat model should be useful in evaluating the mechanism of ED and overactive bladder.

Treatment with hypotensive agents affects the impaired relaxation of the penile corpus cavernosum in hypertensive rats

Treatment of erectile dysfunction (ED) in hypertensive subjects remains to be formally established. There is currently no standardized treatment for ED in hypertensive subjects. In this study, we tested our hypothesis that hypotensive drugs would improve impaired relaxation in the corpus cavernosum of spontaneously hypertensive rats (SHR). Ten-week-old SHR was treated with amlodipine, imidapril or hydralazine for 4 weeks. Although all three drugs achieved an equivalent decrease in systolic blood pressure (SBP), only amlodipine and imidapril induced an increase in relaxation in response to electrical field stimulation (EFS) of the corpus cavernosum. In the case of amlodipine, this effect was dose- and SBP-dependent. Nitric oxide (NO)-dependent relaxation was increased by amlodipine over a wide range of EFS frequencies, was increased by imidapril at low EFS frequencies, and was decreased by hydralazine. Carbon monoxide (CO)-dependent relaxation was only increased by hydralazine, and this increase occurred over a wide range of frequencies. The NOx and cGMP levels in the EFS-stimulated corpus cavernosum were increased by amlodipine. Amlodipine did not affect the thiobarbituric acid-reacting substance levels in the serum and the corpus cavernosum, but did decrease superoxide dismutase activity in the tissue. Imidapril and hydralazine inhibited the acetylcholine-induced relaxation in the corpus cavernosum. Sodium nitroprusside-induced relaxation in the tissue was increased by amlodipine. All three agents similarly inhibited the phenylephrine-induced contraction. These results suggest that impaired neurogenic relaxation in the corpus cavernosum of SHR is improved by amlodipine and imidapril through an increase in the synthesis and/or release of neuronal NO, but not CO, and presumably the inhibited detumescence of erection, which is induced by norepinephrine being released from sympathetic neuron. These findings indicate that amlodipine and imidapril may ameliorate the decreased relaxation of cavernous smooth muscle in the setting of hypertension.

Increased intracavernosal pressure response in hypertensive rats after chronic hemin treatment

INTRODUCTION

Erectile dysfunction (ED) is increased in prevalence in patients with arterial hypertension. Whether upregulation of heme oxygenase (HO) expression could improve penile erection has been unknown.

AIMS

To correlate altered expression profiles of HO-1 and soluble guanylyl cyclase (sGC) in penile tissues with low intracavernosal pressure (ICP) in adult spontaneously hypertensive rats (SHR); and to investigate therapeutic effect of hemin-induced upregulation of HO-1 in penile tissues on ED developed in adult SHR.

METHODS AND MAIN OUTCOME MEASURES

Intracavernosal pressure changes after electrical stimulation were monitored in adult SHR and age-matched normotensive Sprague-Dawley (SD) rats after chronic administration of either hemin or hydralazine. Expression levels of HO-1, HO-2, sGC, and phosphodiesterase type 5 (PDE5) were examined with Western blot.

RESULTS

Frequency-dependent ICP changes were reduced in adult SHR. Three weeks after hemin treatment, high blood pressure of SHR was normalized and ICP responses to electrical stimulations in SHR were significantly increased to the level of normotensive rats. Hydralazine-treated SHR had normalized blood pressure but unaltered low ICP response. Expression of HO-1 and sGC was upregulated and that of PDE5 downregulated in hemin-treated, but not hydralazine-treated, SHR.

CONCLUSIONS

Decreased erectile responses in adult SHR can be improved through chronic hemin treatment. Prolonged upregulation of HO-1 and sGC as well as lowered expression of PDE5 may at least partially explain the effect of hemin treatment on ICP. Upregulation of HO-1 may represent a novel therapeutic approach to treat ED.

Differences Between Candesartan and Hydralazine in the Protection of Penile Structures in Spontaneously Hypertensive Rats

INTRODUCTION

Previous studies indicate that angiotensin type I receptor antagonists present a beneficial effect on penile structures in hypertensive rats. However, at present there is no substantial information concerning the functional aspect of this class of antihypertensive drugs.

AIM

To determine, by in vitro studies, functional effects of Candesartan in comparison with a traditional vasodilating agent, Hydralazine, on penile structures in a rat model of arterial hypertension.

METHODS

During 4 months, three groups of male spontaneously hypertensive rats (SHR) and one of Wistar-Kyoto (WKY) rats, as control group, were studied: SHR without treatment; SHR with Candesartan cilexetil 7.5 mg/kg/day; SHR with Hydralazine 50 mg/kg/day; and WKY rats without treatment. Cavernous smooth muscle strips were mounted in an organ bath system for in vitro studies. In addition, cavernous smooth muscle and vascular smooth muscle from cavernous arteries, cavernous tissue fibrosis, and collagen type III were also evaluated by immunohistochemistry.

RESULTS

After 4 months, SHR with Candesartan and Hydralazine showed similar reduction in blood pressure compared with untreated SHR. However, in vitro studies revealed that SHR with Candesartan displayed a better relaxation response to acetylcholine than SHR and SHR with Hydralazine (P < 0.01). Immunostaining indicates that only SHR with Candesartan and control WKY rats showed significantly lower values of: (i) cavernous smooth muscle (P < 0.01); (ii) vascular smooth muscle (P < 0.01); and (iii) collagen type III (P < 0.01) when compared with untreated SHR or SHR with Hydralazine. Additionally, SHR with Candesartan presented a higher endothelial nitric oxide synthase expression in sinusoidal endothelium in comparison with SHR, and SHR with Hydralazine (P < 0.01).

CONCLUSION

Candesartan presented equivalent blood pressure control compared with Hydralazine. However, only Candesartan showed a significant better response to acetylcholine, in in vitro studies, with a protective role against structural changes in vessels as well as in cavernous spaces of the erectile tissue.

Lower urinary tract symptoms and sexual dysfunction: epidemiology and pathophysiology

There is ample evidence from many epidemiological studies that lower urinary tract symptoms (LUTS) and sexual dysfunction are strongly linked, independently of age and comorbidities such as hypertension, diabetes, dyslipidaemia and coronary heart disease. However, a causal link between both conditions is not yet established. Four pathophysiological mechanisms currently support the relationship between LUTS and erectile dysfunction (ED): (i) The nitric oxide synthase (NOS)/NO theory; there is a reduction in NOS-containing nerves in the prostate and bladder/urethra in patients with bladder outlet obstruction (BOO), and that lack of NO or loss of protein kinase G causes ED; (ii) The autonomic hyperactivity and metabolic syndrome hypothesis: benign prostatic hyperplasia (BPH) may be part of the metabolic syndrome, which includes cardiovascular diseases (e.g. hypertension, ischaemic heart disease) and diabetes mellitus, known risk factors for ED. Hypertension, obesity, and hyperinsulinaemia have all been claimed to be associated with an increased sympathetic activity. Increased sympathetic activity is involved in LUTS/BPH and may have a role in ED/sexual dysfunction, with noradrenaline and alpha1-adrenoceptors representing a common link; (iii) the Rho-kinase activation/endothelin pathway; there can be increased Rho-kinase activity, and consequently calcium sensitivity of the contractile machinery, in prostate smooth muscle in BPH, the detrusor in BOO, corpora cavernosa in ED, and in the resistance vessels in hypertension. The actions of several factors beside noradrenaline (e.g. endothelin-1, angiotensin II), possibly involved in the increased smooth muscle activity found in both LUTS/BPH and sexual dysfunction, are dependent on Rho-kinase activity. Thus increased Rho-kinase activity might represent a common link between LUTS and sexual dysfunction; (iv) Pelvic atherosclerosis; animal models mimicking pelvic ischaemia and hypercholesterolaemia show similar smooth muscle alterations of the detrusor and corpora. Pelvic ischaemia may induce the biological modifications described above and may thus represent as well a common link between LUTS and sexual dysfunction. Studies treating one condition (e.g. ED) and measuring the impact on the other (e.g. LUTS) should further contribute to support this common link.

Coronary endothelial dysfunction is associated with erectile dysfunction and elevated asymmetric dimethylarginine in patients with early atherosclerosis

AIMS

Coronary endothelial dysfunction (CED) precedes atherosclerosis and is associated with cardiovascular events. Both CED and erectile dysfunction (ED) are partly mediated by impairment in the nitric oxide pathway. ED is associated with established coronary atherosclerosis, but its relationship with early coronary atherosclerosis and CED is unknown. This study was designed to test the hypothesis that CED is associated with ED in men with early coronary atherosclerosis. Moreover, the role of the nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) was investigated; ADMA is a novel endogenous competitive inhibitor of nitric oxide synthase and has been shown to be an independent marker for cardiovascular disease.

METHODS AND RESULTS

Fifty-six men without obstructive coronary artery disease (CAD) who underwent coronary endothelial function testing were studied. ADMA levels were determined and all men were asked to complete the International Index of Erectile Function-5 questionnaire to assess erectile function. Patients were divided according to the presence (n = 32) or absence (n = 24) of CED. Men with CED had significant impairment of erectile function (P = 0.008) and significantly higher ADMA levels (0.50 +/- 0.06 vs. 0.45 +/- 0.07 ng/mL, P = 0.017) compared with men with normal endothelial function. Erectile function positively correlated with coronary endothelial function. This correlation was independent of age, body mass index, high-density lipoprotein, C-reactive protein, homeostasis model assessment of insulin resistance index, and smoking status.

CONCLUSION

CED is independently associated with ED and plasma ADMA concentration in men with early coronary atherosclerosis. This study further supports the role of the endothelium in systemic vascular diseases and the role of ADMA in the systemic manifestations of endothelial dysfunction.

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.

Linking erectile dysfunction and coronary artery disease

Coronary artery disease (CAD) and erectile dysfunction (ED) are both highly prevalent conditions that frequently coexist. Additionally, they share mutual vascular risk factors, suggesting that they are both manifestations of systemic vascular disease. The role of endothelial dysfunction in CAD is well established. Normal erectile function is primarily a vascular event that relies heavily on endothelially derived, nitric oxide-induced vasodilation. Accordingly, endothelial dysfunction appears to be a common pathological etiology and mechanism of disease progression between CAD and ED. The risk factors of diabetes mellitus, hypertension, hyperlipidemia, obesity and tobacco abuse contribute to endothelial dysfunction. This article reviews the role of vascular endothelium in health, the abnormalities resulting from vascular risk factors, and clinical trials evaluating the role of endothelial dysfunction in ED.

Prevalence of erectile dysfunction among 7689 patients with diabetes or hypertension, or both

OBJECTIVES

To survey the presence of, and attitudes toward, erectile dysfunction (ED) among patients with hypertension and/or diabetes mellitus who sought general medical care for any reason.

METHODS

The abbreviated five-item version of the International Index of Erectile Function (IIEF-5) was used to determine the presence of ED. A patient questionnaire was used to assess attitudes about ED.

RESULTS

We surveyed 7689 patients (mean +/- SD age 58.9 +/- 9.2 years), including 6719 (87%) in a stable sexual relationship. In patients with hypertension alone (n = 3906) and diabetes alone (n = 2377), ED was reported by 2379 (61%) and 1603 (67%) and was present in 2634 (67%) and 1677 (71%), respectively, as defined by an IIEF-5 score of less than 21. The corresponding mean scores were 12.0 (+/-4.6) and 11.5 (+/-4.6) in patients with ED and 20.5 (+/-3.6) and 20.2 (+/-3.8) in those without ED. Prevalence was affected by disease characteristics and history, and the number and type of antihypertensive medications. ED was reported by 924 (78%) of 1186 patients with both diseases and was present in 917 (77%) according to the IIEF-5 score. Overall, ED was reported by 5063 patients (66%) with hypertension and/or diabetes, was present in 5391 (70%) according to the IIEF-5 score, and increased in prevalence with age. ED was fairly to very bothersome in 4027 (80%) but untreated in 3312 (65%), of whom 2278 (69%) wanted treatment. Most of those wanting treatment would have welcomed discussion with their physician (1861 [82%] of 2278), and most wanted their physician to broach the subject (1292 [69%] of 1861).

CONCLUSIONS

Our study results have shown that patients with diabetes and/or hypertension have a high prevalence of bothersome untreated ED and want their general practitioner to initiate a discussion and provide treatment.

Initial validation of a novel rat model of vasculogenic erectile dysfunction with generalized atherosclerosis

Although rats have been widely used in evaluating various causes of vasculogenic erectile dysfunction (VED), the atherosclerotic rat model has seldom been tried probably due to its inherent tolerance to a cholesterol diet. To enhance endothelial sensitivity to cholesterol diet, we tested the effects of transient interruption of nitric oxide synthase on atherogenesis induced by cholesterol diet in a rat model. Rats with atherosclerosis (AS group) received 1% cholesterol diet for 6 weeks. During the initial 2 weeks, they drank water that contained N(G)-nitro-L-arginine methyl ester (L-NAME) (3 mg/ml). After 6 weeks, we carried out histologic and hemodynamic evaluation to confirm pelvic atherosclerosis and erectile dysfunction, respectively, and the results were compared with those of cholesterol only (Chol) group and normal control (C) group. Compared to the C or Chol group, the mean intima/media (I/M) of the internal pudendal artery, which contributes approximately 70% of the total resistance of the penile vasculature, was markedly increased by the treatment (1.82+/-0.25 vs 0.77+/-0.13, P<0.05). Correspondingly, significantly diminished erectile function was observed. Combined treatment for 2 weeks elicited early atherosclerotic changes in proximal arteries and erectile impairment and further 4 weeks of cholesterol diet spread overt atherosclerosis to the periphery. The Chol group showed no arterial pathology, although they showed mild VED. A correlation study showed that atherosclerosis of the distal artery was better correlated with erectile dysfunction than the proximal artery. Based on these results, our study demonstrates that combination treatment of cholesterol diet with L-NAME would be used as a rapid, effective protocol of developing atherosclerotic rat model of VED.