Ultrastructural comparison of penile cavernous tissue between hypertensive and normotensive rats

Causal effects of hypertension on risk of erectile dysfunction: A two-sample Mendelian randomization study

Background

Erection dysfunction has been associated with hypertension in several epidemiological and observational studies. But the causal association between hypertension and erectile dysfunction requires further investigation.

Methods

A two-sample Mendelian randomization (MR) was conducted to analyze the causal effect of hypertension on risk of erection dysfunction. Large-scale publicly available genome-wide association study data were used to estimate the putative causality between hypertension and risk of erectile dysfunction. A total of 67 independent single nucleotide polymorphisms were selected as instrumental variables. Inverse-variant weighted, maximum likelihood, weighted median, penalized weighted median, and MR-PRESSO approaches were utilized in MR analyses. Heterogeneity test, horizontal pleiotropy test, and leave-one-out method were used to prove the stability of the results.

Results

In total, all P values were less than 0.05, demonstrating a positive causal link between hypertension and risk of erectile dysfunction in multiple MR methods, such as inverse-variant weighted (random and fixed effect) (OR 3.8315, 95% CI 2.3004-6.3817, P = 0.0085), maximum likelihood (OR 3.8877, 95% CI 2.3224-6.5081, P = 0.0085), weighted median (OR 4.9720, 95% CI 2.3645-10.4550, P = 0.0309), penalized weighted median (OR 4.9760, 95% CI 2.3201-10.6721, P = 0.0355), and MR-PRESSO (OR 3.6185, 95% CI 2.2387-5.8488, P = 0.0092). Sensitivity analysis detected no evidence of heterogeneity, pleiotropy, or outlier single nucleotide polymorphisms.

Conclusion

The study revealed a positive causal link between the presence of hypertension and the risk of erectile dysfunction. More attention should be paid during the management of hypertension with the purpose of preventing erectile dysfunction or improving erectile function.

Androgen/Wnt/β-catenin signal axis augments cell proliferation of the mouse erectile tissue, corpus cavernosum

The murine penile erectile tissues including corpus cavernosum (CC) are composed of blood vessels, smooth muscle, and connective tissue, showing marked sexual differences. It has been known that the androgens are required for sexually dimorphic organogenesis. It is however unknown about the features of androgen signaling during mouse CC development. It is also unclear how androgen-driven downstream factors are involved such processes. In the current study, we analyzed the onset of sexually dimorphic CC formation based on histological analyses, the dynamics of androgen receptor (AR) expression, and regulation of cell proliferation. Of note, we identified Dickkopf-related protein 2 (Dkk2), an inhibitor of β-catenin signaling, was predominantly expressed in female CC compared with male. Furthermore, administration of androgens resulted in activation of β-catenin signaling. We have found the Sox9 gene, one of the essential markers for chondrocyte, was specifically expressed in the developing CC. Hence, we utilized CC-specific, Sox9 ^CreERT2 , β-catenin conditional mutant mice. Such mutant mice showed defective cell proliferation. Furthermore, introduction of activated form of β-catenin mutation (gain of function mutation for Wnt/β-catenin signaling) in CC induced augmented cell proliferation. Altogether, we revealed androgen-Wnt/β-catenin signal dependent cell proliferation was essential for sexually dimorphic CC formation. These findings open new avenues for understanding developmental mechanisms of androgen-dependent cell proliferation during sexual differentiation.

Icariin modulates eNOS activity via effect on post-translational protein-protein interactions to improve erectile function of spontaneously hypertensive rats

BACKGROUND

Type 5 phosphodiesterase inhibitor (PDE5I) has become the first-line treatment for erectile dysfunction (ED). However, its effective rate for hypertension ED is only 60%-70%. How to improve the efficacy of ED treatment is the focus of current research.

OBJECTIVE

To explore whether icariin can improve the erectile function of spontaneously hypertensive rats (SHR) by affecting post-translational protein-protein interactions to regulate endothelial nitric oxide synthetase (eNOS) activity.

METHOD

Twelve-week-old healthy male SHR rats and Wistar-Kyoto rats (WKY) were randomly divided into four groups: SHR control group, SHR + icariin (10 mg/kg·d gavage) treatment group, WKY control group, and WKY + icariin (10 mg/kg·d gavage) treatment group (n = 5). After 4 weeks, the maximum penile intracavernous pressure/mean arterial pressure (ICPmax/MAP), the expression of heat-shock protein 90 (Hsp90), caveolin-1, calmodulin, p-eNOS, and eNOS in penile cavernous tissue and the content of nitric oxide (NO) and cGMP were measured. The interaction between eNOS and Hsp90, caveolin-1, and calmodulin were detected by immunoprecipitation.

RESULT

The ICPmax/MAP in the SHR + icariin treatment group (0.08 ± 0.01, 0.23 ± 0.07, 0.40 ± 0.05) was significantly higher than the SHR group (0.03 ± 0.01, 0.13 ± 0.03, 0.21 ± 0.02) under 3V and 5V electrical stimulations (P < .05). Compared with the SHR group, the expression of HSP90, calmodulin, P-eNOS, eNOS, and P-eNOS/eNOS in the penile cavernous tissue of rats in the WKY group and the SHR + icariin treatment group were significantly increased (P < .05), and the expression of caveolin-1 was significantly decreased (P < .05). The NO content (2.16 ± 0.22 μmol/g) and cGMP concentration (3.69 ± 0.12 pmol/mg) in the SHR + icariin treatment group were significantly higher than those in the SHR group (1.01 ± 0.14 μmol/g, 2.31 ± 0.22 pmol/mg) (P < .05). Compared with the SHR group, the interaction between eNOS and HSP90 in the cavernosa of the rats in the SHR + icariin treatment group was significantly increased (P < .05), the interaction between eNOS and caveolin-1 was significantly decreased (P < .01), and the interaction between eNOS and calmodulin did not significantly change.

DISCUSSION AND CONCLUSION

Up-regulating the expression of HSP90 and calmodulin and inhibiting caveolin-1 in SHR corpus cavernosum, promoting the interaction between eNOS and HSP90, inhibiting the interaction between eNOS and caveolin-1, increasing p-eNOS/eNOS, may be the mechanism of icariin that improves SHR erectile function.

Alterations in the phosphodiesterase type 5 pathway and oxidative stress correlate with erectile function in spontaneously hypertensive rats

To explore how alterations in the phosphodiesterase type 5 (PDE5) signalling pathway and oxidative stress correlate with changes in the expression of relaxation and contraction molecules and erectile dysfunction (ED) in the corpus cavernosum smooth muscle (CCSM) of spontaneously hypertensive rats (SHR). In this study, SHR and Wistar‐Kyoto (WKY) rats were used. Erectile function was determined by apomorphine test and electrical stimulation (ES) of cavernous nerve. Masson's trichrome staining and confocal microscopy were performed. Nitric oxide synthase (NOS), PDE5, phosphorylated‐PDE5 and α1‐adrenergic receptor (α1AR) were determined by RT‐PCR and Western blotting while oxidative stress in CC was determined by colorimetric analysis. SHR exhibited obvious ED. CC of SHR showed less SM but more collagen fibres. The expression of NOS isoforms in SHR was significantly decreased while all α1AR isoforms were increased. In addition, PDE5 and phosphorylated‐PDE5 were down‐regulated and its activity attenuated in the hypertensive rats. Meanwhile, the SHR group suffered oxidative stress, which may be modulated by endoplasmic reticulum stress and NADPH oxidase up‐regulation. Dysregulation of NOS and α1AR, histological changes and oxidative stress in CC may be associated with the pathophysiology of hypertension‐induced ED. In addition, PDE5 down‐regulation may lead to the decreased efficacy of PDE5 inhibitors in some hypertensive ED patients and treatment of oxidative stress could be used as a new therapeutic target for this type of ED.

Understanding Erectile Dysfunction in Hypertensive Patients: The Need for Good Patient Management

Erectile dysfunction (ED) is defined as a man’s consistent or recurrent inability to attain and/or maintain penile erection enough for successful vaginal intercourse. ED affects a large part of the population, increasing its incidence with age and comorbidities. It is estimated by the year 2025, 322 million men will suffer from ED. Incidence of ED has been related not only to chronic diseases such as diabetes mellitus, metabolic syndrome, hyperlipidemia, psychiatric diseases or urinary tract diseases, but also to hypertension and especially to antihypertensive treatments. This review summarizes current knowledge about the management of ED in hypertensive men and its role as cardiovascular disease predictor.

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

Relationship of Blood Pressure and Erectile Dysfunction in Men Without Previously Diagnosed Hypertension

BACKGROUND

Erectile dysfunction (ED) is the most common male sexual disorder that affects all age groups and has a close association with essential hypertension.

AIM

To characterize the relation of blood pressure and ED in detail.

METHODS

A cross-sectional population-based study of 45- to 70-year-old men without previously diagnosed hypertension, cardiovascular diseases, renal disease, or diabetes was conducted from 2005 to 2007 in southwestern Finland. A total of 665 men with at least one cardiovascular risk factor were studied. ED was defined by the five-item International Index of Erectile Function.

OUTCOMES

We found a U-shaped association between diastolic blood pressure (DBP) and prevalence of ED.

RESULTS

The average age of the study subjects was 56 ± 6 years and 52% had ED. After adjustment for age, cohabitation status, education, fasting plasma glucose level, waist circumference, and prevalence of depressive symptoms, the curve relating DBP to the prevalence of ED was U-shaped with a nadir of DBP 90 mm Hg.

CLINICAL IMPLICATIONS

Our findings emphasize the importance of blood pressure measurement in the physical examination of men with ED.

STRENGTHS AND LIMITATIONS

This was a cross-sectional study, which prevents the evaluation of causality between ED and hypertension. However, this community-based study population is well defined and the anthropologic measurements were made by trained medical staff.

CONCLUSION

We found a U-shaped correlation between ED and DBP, which confirms the link between ED and hypertension. Heikkilä A, Kaipia A, Venermo M, et al. Relationship of Blood Pressure and Erectile Dysfunction in Men Without Previously Diagnosed Hypertension. J Sex Med 2017;14:1336-1341.

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.

Oral treatment with herbal formula B401 alleviates penile toxicity in aging mice with manganism

The present study aims to elucidate the roles of nitric oxide synthase activity, oxidative stress, inflammation, and apoptosis in penile toxicity of aging mice associated with excess manganese (Mn) treatment and to investigate the effect of oral treatment with the herbal formula B401 in this respect. ICR strain mice were divided into two groups: the vehicle (sham group) and the B401 (50 mg/kg) group. The mice were orally treated for 5 days; then a high single dose of MnCl₂ (100 mg/kg) was given by intraperitoneal injection to the mice. One day after MnCl₂ treatment, corpora cavernosal tissues of both Mn-treated mice and their controls were simultaneously sampled to examine their immunohistochemical staining and Western blot analysis. Nitric oxide (NO) production, levels of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS), expression levels of factors governing angiogenesis (vascular endothelial growth factor), oxidative stress (catalase, superoxide dismutase 2,4-hydroxynonenal), inflammation (tumor necrosis factor alpha), apoptosis (B-cell lymphoma 2 [Bcl-2], Bcl-2-associated X protein [Bax], cleaved poly(adenosine diphosphate-ribose) polymerase [c-PARP], cytochrome C, caspase-12, and caspase-3) were evaluated in penile corpus cavernosum of the mice. We found that penile toxicity in the mice was enhanced under excess Mn treatment through reduction of NOS activity and increase in oxidative stress, inflammation, and apoptosis in the penile cavernous tissue. Furthermore, the penile toxicity in mice with manganism was alleviated by oral B401 treatment through enhancement of both nitric oxide synthesis and angiogenesis, with simultaneous reduction of oxidative stress, inflammation, and apoptosis in penile corpus cavernosum. We suggest that the herbal formula B401 may serve as a potential dietotherapeutic supplement for penile toxicity or dysfunction in aging males.

Age-related changes in the concentration of elastic fibers in different regions of the rabbit penis

PURPOSE

To investigate whether elastic fiber content in the corpus cavernosum (CC), corpus spongiosum (CS) and tunica albuginea (TA) of the rabbit penis undergoes modifications with age.

METHODS

Rabbits were sacrificed, in groups of ten animals each, at 30, 120, 240, and 730 days of age. Histological sections were obtained from the penile middle shaft and were stained with Weigert's resorsin fuchsin. The content of elastic fibers was determined using stereological methods, and was expressed as volume fraction.

RESULTS

At 730 days of age, elastic fiber content was increased by 54% (p<0.004), 78% (p<0.004), and 87% (p<0.004) in the TA, CC, and CS, respectively, compared with animals aged 30 days. After 30 days of age, the concentration gradually and significantly increased until 240 days of age. In 730-day old animals, the concentration, compared with the previous age group, was unchanged in the CC and decreased by 20% (p<0.004) in the TA.

CONCLUSIONS

Elastic fiber contents in the rabbit penis correlate with properties of penile tissues. Although after one month of age there is a gradual increase in these concentrations, in two-year old animals this trend is interrupted, which suggests that this could be an early alteration due to senescence.

Energy restriction ameliorates metabolic syndrome-induced cavernous tissue structural modifications in aged rats

High-fat (HF) diet regular intake along life highly contributes to vascular dysfunction and to an increment in prevalence of metabolic syndrome (MetS) and erectile dysfunction (ED), a surrogate symptom of occult vascular disease, in the elderly. However, little is known about the effects of energy restriction (ER) alone/or after an HF-feeding period. We show here that in male Sprague-Dawley rats, 16 months of HF-diet consumption led to an increase in body adiposity, blood pressure, lipidemia, C-reactive protein, and insulin resistance and to hypoadiponectinemia, conditions that cluster in MetS. In addition, this treatment strongly favored collagen deposition in cavernous tissue and myocardium. Conversely, for the same time period, the ingestion of 75 % of ad libitum energy intake by controls (ER) extensively counteracted these outcomes. The impact of 6-month ER after 10-month HF period was also analyzed, and despite the decrease in body weight, adiposity, blood pressure, lipidemia, and C-reactive protein and improvement of insulin sensitivity, no differences were observed either in adiponectin blood levels or in retroperitoneal fat pad mass. Moreover, this treatment led to a reduction in cavernous tissue collagen deposition, but not in the myocardium, and evidenced differential mobilization of adipose tissue accretions. The data show the ability of HF diet to cause MetS and produce unwanted effects on myocardium and corpora vascular structure. They also indicate that these consequences are preventable upon ER diet starting early, but not later, in life.

Protective effects of hydrogen-rich saline against erectile dysfunction in a streptozotocin induced diabetic rat model

PURPOSE

Hydrogen has antioxidative stress and anti-inflammatory effects. We investigated the effect of hydrogen on erectile dysfunction in streptozotocin induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced in Sprague-Dawley® rats by a single intravenous injection of streptozotocin. Diabetic rats were then randomized to a diabetes mellitus group and to a diabetic group that received hydrogen saline. The latter 8 rats were fed saturated hydrogen saline (5 ml/kg per day) by intragastric administration for 8 weeks. At the end of week 8 erectile function was assessed by measuring the increase in intracavernous pressure after cavernous nerve electrostimulation. We measured nitric oxide synthase activity, and malondialdehyde, 8-hydroxydeoxyguanosine, and nitrite and nitrate in the corpus cavernosum. eNOS protein immunolocalization in cavernous tissues was detected by immunohistochemistry. eNOS, Bcl-2 and Bax protein expression was determined by Western blot. We determined eNOS, Bcl-2 and Bax mRNA using real-time reverse transcriptase-polymerase chain reaction.

RESULTS

Oxidative stress is involved in the pathophysiological mechanism of erectile dysfunction. Maximum intracavernous pressure in diabetic rats decreased significantly compared to controls and increased significantly compared to untreated diabetic rats after hydrogen-rich saline treatment. Decreased nitric oxide synthase activity, nitrite and nitrate, and eNOS expression as well as increased 8-hydroxydeoxyguanosine and malondialdehyde were found in the diabetic group compared to controls. Hydrogen-rich saline improved nitric oxide synthase activity, and malondialdehyde, nitrite and nitrate, and 8-hydroxydeoxyguanosine levels in the diabetic rat corpus cavernosum. Decreased eNOS in diabetic rats was ameliorated by hydrogen-rich saline. Also, apoptosis in the diabetic rat corpus cavernosum was significantly enhanced compared with controls. Hydrogen-rich saline therapy may decrease apoptosis in cavernous tissues and it ameliorated erectile dysfunction in diabetic rats by inhibiting oxidative stress and apoptosis.

CONCLUSIONS

Hydrogen-rich saline effectively improved erectile function in a streptozotocin induced diabetic rat model of erectile dysfunction.

New insights into hypertension-associated erectile dysfunction

PURPOSE OF REVIEW

Erectile dysfunction is recognized as a quality-of-life disorder that needs to be treated. Currently, it is estimated to affect as many as 30 million American men. Thirty percent of hypertensive patients complain of erectile dysfunction. The understanding of common mechanisms involved in the cause of erectile dysfunction associated with hypertension, and the investigation of antihypertensive drugs that impact erectile dysfunction, will provide important tools toward identifying new therapeutic targets that will improve the quality of life for patients in these conditions.

RECENT FINDINGS

Hypertension and erectile dysfunction are closely intertwined diseases, which have endothelial dysfunction as a common base. During hypertension and/or erectile dysfunction, disturbance of endothelium-derived factors can lead to an increase in vascular smooth muscle (VSM) contraction. Hypertension can lead to erectile dysfunction as a consequence of high blood pressure (BP) or due to antihypertensive treatment. However, growing evidence suggests erectile dysfunction is an early sign for hypertension. Also, some phosphodiesterase-5 inhibitors used to treat erectile dysfunction can improve BP, but the link between these conditions has not been totally understood.

SUMMARY

This review will discuss the interplay between hypertension and erectile dysfunction, exploring newest insights regarding hypertension-associated erectile dysfunction, as well as the effect of antihypertensive drugs in erectile dysfunction patients.

Amelioration of diabetes-induced cavernosal fibrosis by antioxidant and anti-transforming growth factor-β1 therapies in inducible nitric oxide synthase-deficient mice

OBJECTIVE

•  To investigate whether sustained long-term separate treatments of diabetic inducible nitric oxide synthase knockout (iNOSKo) mice with allopurinol, an antioxidant inhibiting xanthine oxidoreductase, decorin, a transforming growth factor-β1 (TGFβ1) -binding antagonist, and molsidomine, a long-life nitric oxide donor, prevent the processes of diabetes-induced cavernosal fibrosis.

MATERIALS AND METHODS

•  Eight week old male iNOS knock out (iNOSKo) mice were made diabetic by injecting 150 mg/kg B.W Streptozotocin (1P) with were either left untreated or treated with the oral antioxidant allopurinol (40 mg/kg/day), or decoin (50 mg, 1P, twice), as an anti-TGFβ1 agent (n = 8/group). •  Glycemia and oxidative stress markers were determined in blood and urine. •  Paraffin-embedded tissue sections from the penile shaft were subjected to Masson trichrome staining for the smooth muscle (smc)/collagen ratio, and imunostaining for smc content, profibrotic factors, oxidative stress, cell replication and cell death markers followed by quantitative image analysis.

RESULTS

•  Eight-week treatment with either allopurinol or decorin counteracted the decrease in smooth muscle cells and the increase in apoptosis and local oxidative stress within the corpora tissue. •  Decorin but not allopurinol increased the smooth muscle cell/collagen ratio, whereas allopurinol but not decorin inhibited systemic oxidative stress. •  Molsidomine was effective in reducing both local and systemic oxidative stress, but did not prevent corporal fibrosis.

CONCLUSION

•  Both allopurinol and decorin appear as promising approaches either as a single or a combined pharmacological modality for protecting the diabetic corpora from undergoing apoptosis and fibrosis although their functional effects still need to be defined.

Effect of periodontitis on erectile function and its possible mechanism

INTRODUCTION

Periodontitis is one of the important risk factors resulting in cardiovascular diseases. Erectile dysfunction (ED) is strongly correlated with cardiovascular diseases. The expression of endothelial nitric oxide synthase (eNOS) in penile tissue has an important role in the mechanism of erection.

AIM

To investigate the effect of periodontitis on erectile function and the possible mechanism.

METHODS

After induction of periodontitis in rat, the ratio of maximum intracavernosal pressure/mean arterial pressure (ICPmax /MAP)×100, the expression of eNOS in penile tissue, the level of serum C-reactive protein (CRP) and tumor necrosis factor-α (TNF-α), and the ultrastructural changes of the cavernous tissue were examined and compared between periodontitis rats (group A) and control rats (group B).

MAIN OUTCOME MEASURE

Periodontitis significantly decrease not only the ICPmax/MAP×100 and the expression of eNOS but also the activity of NOS and the level of cyclic guanosine monophosphate (cGMP) in cavernous tissue of rat.

RESULTS

After electrostimulation by 3 and 5 voltage, the ratio of ICPmax /MAP×100 in group A was significantly less than that in group B (19.54±6.16 vs. 30.45±3.12; 30.91±5.61 vs. 50.52±9.52, respectively; P<0.05).The level of serum CRP and TNF-α in group A is significantly higher in group B (P<0.05).The quantitative real-time reverse transcription polymerase chain reaction study demonstrated no statistically significant difference in the expression of mRNA of eNOS in cavernous tissue between the two groups (P>0.05). But there was significant decrease in eNOS protein of the cavernous tissue in group A than in group B (P<0.05). Total NOS activity and cGMP level in cavernosal tissue were significantly lower in group A than in group B (P<0.05). There was no significant alternation occurred in the ultrastructures of penile cavernous tissue.

CONCLUSIONS

The function of penile erection is impaired by periodontitis. The decreased in the expression of eNOS and NOS activity in penile cavernous tissue caused by mild systemic inflammatory status in periodontitis may be one of the important risk factors of ED.

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.

Ultrastructural changes of penile cavernous tissue in multiple sclerotic rats

INTRODUCTION

Multiple sclerosis (MS) is one of the important risk factors resulting in erectile dysfunction (ED). The ultrastructure of corpus cavernous of the penis have an important role in the mechanism of erection.

AIM

It is suggested that different medical conditions produce similar degenerative tissue responses. We investigated the ultrastructural changes of penile cavernous tissue and its association with ED in multiple sclerotic rats.

METHODS

After induction of multiple sclerosis in rat, maximum intracavernosal pressure/mean arterial pressure (ICP(max)/MAP) in the severity multiple sclerotic rats (group A),moderate multiple sclerotic rats (group C), and age-matched control rat (group B) were observed and compared. The ultrastructure of the penile cavernous tissue was studied by transmission electron microscope. Expression of neuronal nitric oxide synthase (nNOS) in penile tissue were examined immunohistochemically.

MAIN OUTCOME MEASURES

Severity MS (score 3) not only significantly decrease the ICPmax/MAP x 100 and the expression of nNOS, but also might affect the ultrastructure of the penis.

RESULTS

The ICP(max)/MAP x 100 in group A was significantly less than in group B and group C at 3 V (5.65 +/- 1.78, 20.49 +/- 5.84, and 12.78 +/- 5.76, respectively) and at 5 V (6.70 +/- 1.39, 23.66 +/- 5.19, and 16.95 +/- 3.31, respectively) stimulation voltage, respectively (P < 0.05). Significant ultrastructral pathological changes characterized by degeneration and demyelination singularly in Schwann cells without significant ultrastructural change of smooth muscle cells and endothelium cells were observed in penile cavernous tissue of group A rats.

CONCLUSIONS

The function of penile erection is affected by MS, and the ultrastructural pathological changes of the penile cavernous tissue may be one of the important mechanisms of ED caused by severity MS.

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.

Effect of muscle-derived stem cells on the restoration of corpora cavernosa smooth muscle and erectile function in the aged rat

OBJECTIVE

To determine whether skeletal muscle-derived stem cells (MDSCs) convert into smooth muscle cells (SMCs) both in vitro and in vivo, and in so doing ameliorate the erectile dysfunction (ED) of aged rats, and whether endogenous stem cells are present in the rat corpora cavernosa.

MATERIALS AND METHODS

MDSCs were obtained from mouse muscle, and shown by immunocytochemistry for alpha-smooth muscle actin (alpha SMA) to originate in vitro in myofibroblasts and SMCs, discriminating SMCs by calponin 1 expression. In vivo these MDSCs, labelled with 4',6-diamidino-2-phenylindole, were implanted into the corpora cavernosa of young adult (5-month old) and aged (20-month old) rats for 2 and 4 weeks. Histological changes were assessed by immunohistochemistry and quantitative Western blot. Functional changes were determined by electrical field stimulation (EFS) of the cavernosal nerve.

RESULTS

The exogenous cells replicated and converted into SMCs, as shown in corporal tissue sections by confocal immunofluorescence microscopy for proliferating cell nuclear antigen (PCNA), alpha SMA, and smoothelin, and also by Western blot for alpha SMA and PCNA. MDSC differentiation was confirmed by the activation of the alpha SMA promoter-linked beta-galactosidase in transfected cells, both in vitro and after implantation in the corpora. Putative endogenous stem cells were shown in corporal tissue sections and Western blots by detecting CD34 and a possible Sca1 variant. EFS showed that implanted MDSCs raised in aged rats the maximal intracavernosal pressure/mean arterial pressure levels above (2 weeks) or up to (4 weeks) those of young adult rats.

CONCLUSIONS

MDSCs implanted into the corpora cavernosa of aged rats converted into SMCs and corrected ED, and endogenous cells expressing stem cell markers were also found in untreated tissue. This suggests that exogenous stem cell implantation and/or endogenous stem cell modulation might be viable therapeutic approaches for ageing-related 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.