Elevation of intracavernous pressure and NO-cGMP activity by a new herbal formula in penile tissues of aged and diabetic rats

The protective effect of Ferula elaeochytris on age-related erectile dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Ferula elaeochytris Korovin (FE) is a perennial medicinal plant of Apiaceae family. Ferula elaeochytris Korovin, known as 'Çakşır' in Anatolia, is widely used as an aphrodisiac as well as antioxidant, anti-inflammatory, and anti-diabetic.

AIM OF THE STUDY

Erectile dysfunction (ED) is a serious public health problem that has a high prevalence and negatively affects the quality of life in elderly men. In the treatment and prophylaxis of many diseases, because of widely increasing use of plant extracts as therapeutic agents, preclinical studies related to plant extracts are becoming more important by the day. In this study, we aimed to investigate the protective effect of Ferula elaeochytris Korovin (FE) root extract on age-related ED.

MATERIALS AND METHODS

Seventy-two male Wistar albino rats were equally divided into four groups: 4-month aged rats (Y), 24-month aged rats (AG), and FE-administered (20 and 40 mg/kg/day; oral gavage; over 8 weeks) 24-month aged rats (AG + FE). The measurements included: changes in smooth muscle cells and collagen fibrils, tumor necrosis factor alpha (TNF-α), penile neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) expression, serum testosterone concentrations (ST), neurogenic- and endothelial-dependent relaxations of the corpus cavernosum (CC), intracavernosal pressure/mean arterial pressure (ICP/MAP), area under the curve (total ICP), total antioxidant status (TAS), and total oxidant status (TOS) on corpus cavernosal tissue.

RESULTS

These results have an important role in the development of ED. ICP/MAP, total ICP, eNOS/nNOS expressions and ST levels increased in AG+40 mg FE group compared to the AG group, whereas TNF-α levels decreased and oxidative and antioxidant parameters balanced.

CONCLUSIONS

Our findings show that FE may have a useful effect on decelerating the development of age-related ED.

Combined treatment with extracorporeal shockwaves therapy and an herbal formulation for activation of penile progenitor cells and antioxidant activity in diabetic erectile dysfunction

Background

A Korean herbal formulation named KH-204 was reported to have an antioxidant effect in our previous study. We hypothesized that Low-intensity extracorporeal shockwave therapy (Li-ESWT) combined with KH-204 would accelerate the treatment of erectile dysfunction (ED) by enhancing antioxidant. We investigated the synergistic effect of Li-ESWT and KH-204 for ED and explored the mechanism.

Methods

Human umbilical vein endothelial cells (HUVEC) were treated with KH-204 and LI-ESWT in vitro. Fifty 5-week-old male Sprague Dawley rats received an intraperitoneal injection of 5-ethynyl-20-deoxyuridine (EdU) which can label live cells, and were randomly divided into five groups: (I) normal; (II) diabetes mellitus-associated erectile dysfunction (DMED); (III) DMED + KH-204; (IV) DMED + Li-ESWT; and (V) DMED + KH-204/Li-ESWT. Li-ESWT treatment was repeated three times a week every other day for four weeks in group 4 and 5. Meanwhile, rats in group 3 and 5 were orally fed 400 mg/kg of KH-204 daily for 1 month. Following a 1-week washout period, penile tissues were evaluated by immunostaining and Western blotting.

Results

KH-204 combined with Li-ESWT improved intracavernosal pressure (ICP) in DMED rats. Li-ESWT/KH-204 stimulated HUVEC tube formation and promoted proliferation. Li-ESWT drove progenitor cells to migrate to penile tissue and KH-204 protected penile progenitor cells in the corpus cavernosum. Oxidative stress was relieved by KH-204/Li-ESWT. Treatment with KH-204/Li-ESWT protected penile progenitor cells, which were recruited to the corpus cavernosum by Li-ESWT, from apoptosis via its antioxidant activity. KH-204/Li-ESWT protected penile tissue from oxidative stress by improving the expression of nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1), increasing superoxide dismutase (SOD), decreasing 8-hydroxy-20-deoxyguanosine (8-OHdG), and reducing apoptosis. KH-204/Li-ESWT promoted stromal derived factor-1 (SDF-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1) in DMED rats.

Conclusions

KH-204 protected penile progenitor cells, which were recruited to the corpus cavernosum by Li-ESWT, from apoptosis via its antioxidant activity. The combination of Li-ESWT and KH-204 as a synergy therapy could be a potential and effective treatment for DMED.

Efficacy and safety of an herbal formula (KBMSI-2) in the treatment of erectile dysfunction: A preliminary clinical study

Purpose

To investigate the efficacy and safety of KBMSI-2, an herbal formula consisting of Ginseng Radix Rubra, Dioscorea tenuipes, Cornus officinalis Sieb. et Zucc., Lycium chinense Mill, and Curcuma longa Linn, for the treatment of erectile dysfunction (ED).

Materials and Methods

Patients were instructed to take placebo or 6 g of KBMSI-2 twice per day for 8 weeks, at least 1 hour after food intake. The primary outcome was a change from baseline in erectile function (EF) domain scores of the International Index of Erectile Function (IIEF) questionnaire. Secondary outcome included changes from baseline in all domain scores of the IIEF, scores on the Aging Males' Symptoms scale, and serum total testosterone levels, as well as changes in questions 2 and 3 of the Sexual Encounter Profile, responses to the Global Assessment Question, and changes in the number of ‘yes’ responses on the Androgen Deficiency in Aging Males questionnaire.

Results

Patients receiving KBMSI-2 had a statistically significant improvement in baseline IIEF-EF domain scores at 8 weeks compared to the placebo group. Intercourse satisfaction domain and the total IIEF scores also increased in the KBMSI-2 group. However, we could not find any significant differences in other efficacy variables between the groups. Only one patient had an adverse event, which was mild in severity.

Conclusions

This preliminary clinical study of KBMSI-2 shows significant improvements in EF and intercourse satisfaction, as measured by the IIEF in patients with ED. Further studies using a larger number of patients in the long term should follow.

Effects of a combination of herbal extracts (modified Ojayeonjonghwan (Wuzi Yanzong wan)) on partial urethral obstruction-induced detrusor overactivity in rats: impact on the nitric oxide pathway and oxidative stress

Background

We investigated the effects of a berry mixture formula (modified Ojayeonjonghwan (Wuzi Yanzong Wan, MO formula) on detrusor overactivity (DO).

Methods

The MO formula consisted of 5 seeds obtained from 5 types of berry plants. Twenty-four Sprague-Dawley rats were randomly assigned to four groups: sham-operated (control), partial urethral obstruction-induced DO (DO group), 0.03 mg/kg solifenacin-treated DO (solifenacin group) and 200 mg/kg MO formula -treated DO (berry mixture). The control and overactive groups were administered distilled water for 4 weeks, and the solifenacin and MO formula groups were treated with the respective medication for 4 weeks. After treatment, cystometrography was performed. At the endo of cystometrography, their bladder tissues were used for identifying the muscarinic receptors, endothelial nitric oxide synthase(eNOS), RhoA, Rock-I & II, 8-hydroxy-2′ –deoxyguanosine(8-OHdG), superoxide dismutase(SOD), interleukin-6 &-8(IL-6, IL-8), and tumor necrosis factor-alpha(TNF-a). The tissues were stained and the muscle-to-collagen ratio was identified.

Results

The presence of the muscarinic receptors were not significantly different between the solifenacin and MO formula groups. However, significant differences were found between the solifenacin and MO formula groups in terms of eNOS, RhoA, Rock-I and -II levels. The muscle-to-collagen ratio was statistically lower in the DO and solifenacin groups; however, no significant difference was observed between the control and MO formula groups. Under oxidative stress, SOD showed a similar result as 8-OHgG. The MO formula group exhibited anti-inflammatory effects, showing that no significant difference was found between the control and MO formula groups regarding values of IL-6, IL-8, and TNF-a. However, the DO and solifenacin groups showed increased IL-6, IL-8, and TNF-a levels. Cystometrography showed that the OAB and solifenacin groups having a significantly lower value than the control and MO formula groups. The mean contraction interval was shorter in the DO, MO formula, and solifenacin groups and the highest in the control group.

Conclusions

The MO formula exhibited a similar pharmacologic effect to that of solifenacin, with anti-inflammatory and antioxidant effects. Enhancement of the MO formula by the nitric oxide pathway affected DO including BPH-related DO. The MO formula may be one of the alternative choices of anticholinergics, a treatment for DO.

Effect of Korean Herbal Formula (Modified Ojayeonjonghwan) on Androgen Receptor Expression in an Aging Rat Model of Late Onset Hypogonadism

Purpose

Testosterone replacement therapy is an effective treatment for late-onset hypogonadism (LOH) despite a few contraindications and side-effects. The aim of this study was to determine whether modified Ojayeonjonghwan (KH-204, Korean herbal formula) improved LOH. KH-204 is a strong antioxidant herbal formula. We evaluated the effect of Korean herbal prescription on androgen receptor (AR) expression in an aged rat model of LOH.

Materials and Methods

Eighteen-month-old rats were used as aged LOH rat models. Eighteen Sprague-Dawley rats were randomly divided into three equal groups of six animals each and treated with one of the following: 1) normal control group (oral administration with distilled water, n=6), 2) KH-204 200 group (oral administration with 200 mg/kg of KH-204, n=6), and 3) KH-204 400 group (oral administration with 400 mg/kg of KH-204, n=6). After four weeks of treatment (once daily, distilled water or KH-204), serum testosterone levels, changes in testicular and epididymal weight, Western blotting analysis of AR expression and measurement of oxidative stress were examined.

Results

Treatment with the herbal formulation KH-204 200 mg/kg and 400 mg/kg (1) increased the weights of testis and epididymis; (2) increased the level of serum testosterone; (3) increased the level of superoxide dismutase and reduced the level of 8-hydroxy-20-deoxyguanosine; and (4) upregulated AR expression in testicular tissue.

Conclusions

KH-204 might be an effective alternative for LOH. It improves antioxidant mechanisms and increases testicular AR expression without side-effects.

Diabetic dyslipidaemia is associated with alterations in eNOS, caveolin-1, and endothelial dysfunction in streptozotocin treated rats

BACKGROUND

Diabetes is a complex progressive disease characterized by chronic hyperglycaemia and dyslipidaemia associated with endothelial dysfunction. Oxidized LDL (Ox-LDL) is elevated in diabetes and may contribute to endothelial dysfunction. The aim of this study was to relate the serum levels of Ox-LDL with endothelial dysfunction in streptozotocin (STZ)-diabetic rats and to further explore the changes in endothelial nitric oxide synthase (eNOS) and caveolin-1 (CAV-1) expression in primary aortic endothelial cells.

METHODS

Diabetes was induced with a single intraperitoneal injection of STZ in male Wistar rats. During the hyperglycaemic diabetes state serum lipid markers, aortic relaxation and aortic endothelial cell eNOS and CAV-1 protein expressions were measured.

RESULTS

Elevated serum Ox-LDL (STZ 1486 ± 78.1 pg/mL vs control 732.6 ± 160.6 pg/mL, P < .05) was associated with hyperglycaemia (STZ 29 ± 0.9 mmol/L vs control: 7.2 ± 0.2 mmol/L, P < .001) and hypertriglyceridaemia (STZ 9.0 ± 1.5 mmol/L vs control: 3.0 ± 0.3 mmol/L, P < .01) in diabetic rats. A significant reduction was observed in STZ-diabetic aortic endothelial cell eNOS and CAV-1 of 40% and 30%, respectively, accompanied by a compromised STZ-diabetic carbachol-induced vasodilation (STZ 29.6 ± 9.3% vs control 77.2 ± 2.5%, P < .001).

CONCLUSIONS

The elevated serum Ox-LDL in hyperglycaemic STZ-diabetic rats may contribute to diabetic endothelial dysfunction, possibly through downregulation of endothelial CAV-1 and eNOS.

Antioxidant and Antifibrotic Effect of a Herbal Formulation In Vitro and in the Experimental Andropause via Nrf2/HO-1 Signaling Pathway

The Korean herbal formulation Ojayeonjonghwan is used for improving late-onset hypogonadism (LOH) symptoms such as erectile dysfunction (ED). A previous research suggested that a modified Ojayeonjonghwan (KH-204) could be used as an alternative to the treatment for ED. The pharmacological effects were examined in different conditions, including in vitro and in vivo. We measured the survival rate of TM3 Leydig cells under the oxidative stress condition. The s.c. injection of leuprorelin was used to induce androgen deprivation. We measured serum testosterone levels, oxidative stress, and apoptosis. The results of the treatment by KH-204 (1) preserved TM3 cells from oxidative stress by improving the expression of nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1); (2) lowered the expression of transforming growth factor-beta (TGF-β) 1/SMAD; (3) increased the average of serum testosterone in androgen-deprived male rats; (4) kept the activation of spermatogenesis; (5) upgraded the contents of 8-hydroxy-20-deoxyguanosine (8-OHdG) and degraded the contents of superoxide dismutase (SOD); and (6) reduced apoptosis. We studied that KH-204 improved testicular dysfunction in LOH. It is likely, at least in part, to degrade oxidative stress through the Nrf2/HO-1 pathway. These findings may offer credible evidences for the use of new alternative therapies to treat LOH.

The herbal formula KH-204 is protective against erectile dysfunction by minimizing oxidative stress and improving lipid profiles in a rat model of erectile dysfunction induced by hypercholesterolaemia

Background

Hypercholesterolaemia (HC) is a major risk factor for ischemic heart disease and is also known to be a risk factor for erectile dysfunction (ED). ED caused by HC is thought to be related to HC-induced oxidative stress damage in the vascular endothelium and erectile tissue. KH-204 is an herbal formula with a strong antioxidant effect. We evaluated the effects of KH-204 on erectile function in a rat model of HC-induced ED.

Methods

Male Sprague-Dawley rats (6 weeks old) were divided into normal control, high-fat and cholesterol diet (HFC), and HFC with KH-204 treatment (HFC + KH) groups (n = 12 each). Normal control group rats were fed normal chow diet. HFC and HFC + KH group rats were fed high-fat and cholesterol diets and treated with or without daily oral doses of KH-204 for 12 weeks. Subsequently, intracavernous pressure (ICP) and mean arterial pressure (MAP) were measured, and lipid profiles, expression of endothelial (eNOS) and neuronal (nNOS) nitric oxide synthase, oxidative stress (8-hydroxy-2-deoxyguanosine), and ratio of smooth muscle cells and collagen fibres were evaluated in the serum and corpora tissue.

Results

Compared to the HFC group, the HFC + KH group showed statistically significant increases in peak ICP and ICP/MAP ratio, expression of eNOS and nNOS, and ratio of smooth muscle cells and collagen fibres (p < 0.05). The HFC + KH group also showed statistically significant decreases in oxidative stress (p < 0.05). Further the lipid profiles of this group were ameliorated compared to those of the HFC group (p < 0.05).

Conclusions

The current study shows that the antioxidant and hypolipidemic effects of KH-204 are effective in ameliorating ED by restoring endothelial dysfunction and suggests that KH-204 may be a potential therapeutic agent for ED by correcting the fundamental cause of ED.

Administration of Goji (Lycium chinense Mill.) Extracts Improves Erectile Function in Old Aged Rat Model

Purpose

This study investigated the effect of goji (Lycium chinense Mill.) on erectile dysfunction in old-aged rats.

Materials and Methods

Twenty-four 18-month-old male Sprague-Dawley rats (defined as old-aged rats) were used. Treatment groups contained eight rats each: a control group, goji extract of 150 mg/kg/day group, and goji extract of 300 mg/kg/day group. Treatment was by orogastric tube once daily for 6 weeks. After 6 weeks of treatment, testes weight, serum testosterone, superoxide dismutase, nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-related parameters, intracavernous pressure/mean arterial pressure, and histological changes were examined.

Results

Treatments with goji extracts increased serum testosterone level, increased the expression of endothelial NO synthase, neuronal NO synthase, and cGMP, improved the oxidative stress marker, and decreased corporal fibrosis.

Conclusions

Our results indicate that goji extract may have a positive effect on erectile dysfunction via its antioxidant effects.

Beneficial Effects of Scutellaria baicalensis on Penile Erection in Streptozotocin-Induced Diabetic Rats

We have reported that ethanol extracts of the root from Scutellaria baicalensis Georgi (ESB) relax cavernous smooth muscles via the NO/cGMP system and Ca[Formula: see text]-sensitive K[Formula: see text] channels in the rabbit corpus cavernosum. In the present study, erectile function was assessed by intracavernous pressure (ICP) and mean arterial pressure (MAP) during electrical stimulation of the cavernous nerve. The ICP/MAP ratio was dose-dependently increased by the treatment of ESB in normal SD rats ([Formula: see text]). To investigate the beneficial effect of ESB on erectile dysfunction in a diabetic animal model, male SD rats were injected with streptozotocin (60[Formula: see text]mg/kg) and then 300[Formula: see text]mg/kg/day ESB was administered daily for eight weeks. In our in vivo study, administration of ESB in STZ rats significantly increased the ICP, ICP/MAP ratio, area under the curve (AUC), as well as the cavernous cGMP levels. Morphometric analyses showed that ESB administration increased both smooth muscle volume and the regular arrangement of collagen fibers compared to the STZ group. The protein expression levels of endothelial nitric oxide synthase (eNOS) and SM [Formula: see text]-actin from penile tissues were also significantly increased in the ESB-treated rats. Taken together, these results suggest that ESB ameliorates penile erectile dysfunction via the activation of the NO/cGMP pathways of the penile corpus cavernosum in a streptozotocin-induced diabetic rat model.

Protective Effects of KH-204 in the Bladder of Androgen-Deprived Rats

Purpose

We investigated the protective effects of the herbal formulation KH-204 in the bladder of androgen-deprived rats.

Materials and Methods

Male rats aged eight weeks were randomly divided into four groups, containing eight rats each: sham operation only (normal control group), androgen-deprived only (androgen-deprived control group), and androgen-deprived followed by treatment with 200 mg/kg or 400 mg/kg of KH-204. After 0.5 mg/kg of leuprorelin was subcutaneously injected in the androgen-deprived groups, the oral administration of either distilled water in the two control groups or KH-204 in the treatment group was continued for four weeks. Serum testosterone levels, RhoGEF levels, nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-related parameters, oxidative stress, and histologic changes were evaluated after treatment.

Results

Treatment with the herbal formulation KH-204 (1) increased serum testosterone levels; (2) restored the expression of RhoGEFs, endothelial NO synthase, and neuronal NO synthase; (3) increased the expression of superoxide dismutase; and (4) decreased bladder fibrosis.

Conclusions

Our results suggest that the positive effects of KH-204 on the urinary bladder may be attributed to its antioxidant effects or to an elevation in NO-cGMP activity.

Current Status and Clinical Studies of Oriental Herbs in Sexual Medicine in Korea

Erectile dysfunction (ED) is one of the most common diseases among aging men. Although previous studies have shown that type 5 phosphodiesterase inhibitors (PDE5-Is) are very effective for the treatment of ED, many researchers are currently attempting to identify therapeutic agents from natural sources with comparable or better effects than PDE5-Is. Herbal medicine is thought to be advantageous because it is natural; moreover, it not only treats isolated symptoms, but also maintains general well-being. Furthermore, since newly created chemical compound libraries have limited structural diversity with regard to pharmaceutical agents, more attention has recently been paid to the ability of oriental herbs to enhance physical health, including sexual function. Herein, we review the current status of Korean preclinical or clinical studies of the application of oriental herbs to sexual medicine.

Pravastatin improves the impaired nitric oxide-mediated neurogenic and endothelium-dependent relaxation of corpus cavernosum in aged rats

AIM

The aim of this study was to investigate the effect of pravastatin treatment on diminished corpus cavernosum (CC) function associated with aging.

METHODS

Male rats were divided into three groups as adult rats (12-14 weeks old), aged rats (72-80 weeks old) and aged rats given 10 mg/kg/d pravastatin in drinking water for six weeks. Blood pressure was measured by tail-cuff method. Total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, triglycerides and testosterone levels were estimated in blood. Changes in expression levels of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) (Ser-1177), neuronal nitric oxide synthase (nNOS), NADPH oxidase subunit gp91(phox), Rho A and Rho kinase (ROCK2) in CC were assessed by immunohistochemistry. Nitric oxide (NO)-mediated endothelium-dependent and neurogenic CC relaxation were evaluated by acetylcholine (ACh, 0.1 nM-100 µM) and electrical field stimulation (EFS; 30 V, 5 ms, 2-32 Hz), respectively.

RESULTS

In aged rats, NO-mediated, both endothelium-dependent and neurogenic CC relaxation, were significantly impaired as compared to adult rats. Besides, eNOS, p-eNOS and nNOS expressions decreased significantly in CC from aged rats, while gp91(phox), RhoA and ROCK2 expressions increased significantly. The diminished relaxation in response to ACh or EFS as well as the changes in expression of these proteins in aged rats were significantly improved by pravastatin treatment.

CONCLUSION

Pravastatin improves NO-mediated CC relaxations of aged rats probably by inhibiting NADPH oxidase/Rho kinase pathways, and this effect does not seem to be associated with lipid lowering effect of this drug.

The effects of new herbal formula (KBMSI-2) on penile erection and expression of nitric oxide synthase isoforms in streptozotocin-induced diabetic rat model

OBJECTIVE

To investigate the effects of new herbal formula (KBMSI-2) on erectile dysfunction in streptozotocin (STZ)-induced diabetic rat model.

METHODS

Twenty four Sprague-Dawley male rats were randomly divided into three groups; control (n=8), diabetes model (n=8), diabetes + KBMSI-2 200 mg/kg treatment (n=8) groups. The diabetes induced groups received a single intraperitoneal injection of STZ. Distilled water was administered in the control and model groups. To investigate the penile erection, intracavernosal pressure (ICP) and intracavernosal pressure/mean arterial pressure (ICP/MAP) were recorded in all groups. Serial sections of the penis were used to perform Masson's trichrome stain. The expression of neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS) and cyclic guanosine monophosphate (cGMP) concentration in the isolated corpus cavernosum were analyzed by Western blotting.

RESULTS

Peak ICP/MAP ratio was increased in the KBMSI-2 treatment group compared with the model group (P<0.05). Masson's trichrome staining confirmed that the smooth muscle component was increased in the KBMSI-2 treatment group compared with the model group (P<0.05). The nNOS, eNOS and cGMP expression of KBMSI-2 200 mg/kg treatment group was increased compared with the model group (P<0.05).

CONCLUSION

This study showed that herbal formula of KBMSI-2 improved the erectile function by preserving the smooth muscle content and inhibiting the fibrosis of the corpus cavernosum in STZ-induced diabetic rat model.

Evaluation and treatment of erectile dysfunction in the aging male: a mini-review

Before the 20th century, individuals often did not live beyond the reproductive years, and sexuality of the elderly was not an issue. However, in the current era it is known that as life expectancy improves, both men and women are seeking to preserve their sexuality into old age. While the appreciation of sexuality persists with aging, a decline in sexual activity is typically seen with, and can be attributed to both general health problems as well as specific sexual dysfunctions. Erectile dysfunction is the most frequently diagnosed sexual dysfunction in the older male population. This mini-review provides an overview of contemporary literature concerning epidemiology, pathophysiology, assessment and treatment of erectile dysfunction in the aging male.

Erectile dysfunction in young non-obese type II diabetic Goto-Kakizaki rats is associated with decreased eNOS phosphorylation at Ser1177

INTRODUCTION

Diabetes mellitus (DM) is a risk factor for erectile dysfunction (ED). Although type 2 DM is responsible for 90-95% diabetes cases, type 1 DM experimental models are commonly used to study diabetes-associated ED.

AIM

Goto-Kakizaki (GK) rat model is relevant to ED studies since the great majority of patients with type 2 diabetes display mild deficits in glucose-stimulated insulin secretion, insulin resistance, and hyperglycemia. We hypothesized that GK rats display ED which is associated with decreased nitric oxide (NO) bioavailability.

METHODS

Wistar and GK rats were used at 10 and 18 weeks of age. Changes in the ratio of intracavernosal pressure/mean arterial pressure (ICP/MAP) after electrical stimulation of cavernosal nerve were determined in vivo. Cavernosal contractility was induced by electrical field stimulation (EFS) and phenylephrine (PE). In addition, nonadrenergic-noncholinergic (NANC)- and sodium nitroprusside (SNP)-induced relaxation were determined. Cavernosal neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) mRNA and protein expression were also measured.

MAIN OUTCOME MEASURE

GK diabetic rats display ED associated with decreased cavernosal expression of eNOS protein.

RESULTS

GK rats at 10 and 18 weeks demonstrated impaired erectile function represented by decreased ICP/MAP responses. Ten-week-old GK animals displayed increased PE responses and no changes in EFS-induced contraction. Conversely, contractile responses to EFS and PE were decreased in cavernosal tissue from GK rats at 18 weeks of age. Moreover, GK rats at 18 weeks of age displayed increased NANC-mediated relaxation, but not to SNP. In addition, ED was associated with decreased eNOS protein expression at both ages.

CONCLUSION

Although GK rats display ED, they exhibit changes in cavernosal reactivity that would facilitate erectile responses. These results are in contrast to those described in other experimental diabetes models. This may be due to compensatory mechanisms in cavernosal tissue to overcome restricted pre-penile arterial blood supply or impaired veno-occlusive mechanisms.

Changes in caveolin-1 expression and vasoreactivity in the aorta and corpus cavernosum of fructose and streptozotocin-induced diabetic rats

Hyperglycemia is a common defining feature in the development of endothelial dysfunction which plays a key role in the pathogenesis of both type 1 and type 2 diabetes. Caveolin-1 is the main structural component of caveolae which might be involved in the pathophysiology of macrovascular complications of diabetes. In this study we aimed to observe the effect of caveolin-1 on functional responses of aorta and corpus cavernosum in the streptozotocin and fructose-induced diabetes groups. Type 1 diabetes was induced by intraperitoneal administration of streptozotocin (60 mg/kg),. Type 2 diabetes by adding fructose in the rat's drinking water (10% (w/v)) for 8 weeks. For insulin treatment; rats were treated with insulin (6 U/kg) for 8 weeks. In Type I and Type II diabetic groups the contractile responses of corpus cavernosum strips to phenylephrine (EC(50):1.82 x 10(-5)M;1.47 x 10(-5)M, respectively)and relaxation responses to acetylcholine (EC(50):7.5 x 10(-5)M;4.48 x 10(-5)M, respectively)were significantly impaired. Contractile responses of aorticstrips to phenylephrine in diabetic groups were markedly decreased (EC(50):3.7.10(-7)M;2.61.10(-7)M respectively) and dose-dependent relaxation responses to acetylcholine were also attenuated (EC(50):3.23.10(-6)M; 2.0.10(-6)M respectively). Treatment with insulin improved the functional responses in the aorta and corpus cavernosum. Protein expression of caveolin-1 was increased in the aorta and corpus cavernosum of the diabetic groups, but this increase seen in the streptozotocin group was more significant than the fructose group. Our findings indicate that an attenuation of the functional responses in both diabetes groups were probably associated with an enhanced expression of caveolin-1, and therefore a decrease in the eNOS activity with a concomitant decrease in NO synthesis.

Type 1 and Type 2 diabetic-erectile dysfunction: same diagnosis (ICD-9), different disease?

INTRODUCTION

Although hyperglycemia is a common defining feature of both type 1 and type 2 diabetes, many unique characteristics distinguish these diseases, including insulin and lipid levels, obesity status, and inflammatory agent profiles. In the laboratory, the presence of erectile dysfunction (ED) has been established in animal models of both type 1 and type 2 diabetes.

AIM

The purpose of this study was to determine whether unique mechanisms underlie ED in type 1 vs. type 2 diabetic animal models.

MAIN OUTCOME MEASURES

Many mechanisms can underlie ED, including impaired dilatory signaling, heightened contractile sensitivity, and veno-occlusive disorder.

METHODS

Using PubMed, the literature was mined to evaluate what is known about which mechanism underlie ED in type 1 vs. type 2 diabetic animal models.

RESULTS

Impaired cavernosal vasodilation has been established in type 1 diabetic rodents. This dysfunction appears to be mediated by a severe defect in non-adrenergic-non-cholinergic nerve signaling, as well as impairment in penile endothelial function. In contrast, type 2 diabetic animals appear to have minimal impairment in parasympathetic-mediated dilatory function, but do have evidence of endothelial dysfunction. Type 2 diabetic models also exhibit a significant and striking increase in cavernosal contractile sensitivity, and a significant veno-occlusive disorder, neither of which is consistently reported in type 1 diabetic animals.

CONCLUSIONS

With the distinct mechanisms underlying the ED phenotype in animal models of type 1 and type 2 diabetes, tailoring therapeutic treatments for diabetic-ED to the specific mechanisms underlying this disease complication may be warranted. Further examination of mechanisms underlying ED in diabetic human patients may thus lead to significant changes in the way urologists diagnose, code, and treat diabetic-ED.

Posttranslational modification of constitutive nitric oxide synthase in the penis

Erectile dysfunction (ED) is a common men's health problem characterized by the consistent inability to sustain an erection sufficient for sexual intercourse. Basic science research on erectile physiology has been devoted to investigating the pathogenesis of ED and has led to the conclusion that ED is predominately a disease of vascular origin, neurogenic dysfunction, or both. The constitutive forms of nitric oxide synthase (NOS, endothelial [eNOS] and neuronal [nNOS]) are important enzymes involved in the production of nitric oxide (NO) and thus regulate penile vascular homeostasis. Given the effect of endothelial- and neuronal-derived NO in penile vascular biology, a great deal of research over the past decade has focused on the role of NO synthesis from the endothelium and nitrergic nerve terminal in normal erectile physiology, as well as in disease states. Loss of the functional integrity of the endothelium and subsequent endothelial dysfunction plays an integral role in the occurrence of ED. Therefore, molecular mechanisms involved in dysregulation of these NOS isoforms in the development of ED are essential to discovering the pathogenesis of ED in various disease states. This communication reviews the role of eNOS and nNOS in erectile physiology and discusses the alterations in eNOS and nNOS via posttranslation modification in various vascular diseases of the penis.

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.

Elevation of Nitric Oxide Synthase Activity by Dimethyladenosine from Silkworm Pupae in Aged Rats

This study examined the mechanisms underlying the effects of the vasorelaxation active substance (VAS), dimethyladenosine-5’-L-arabinose, and its partial purification fraction on nitric oxide synthase in improving erectile dysfunction with particular focus on the nitric oxide (NO)-cGMP pathways. Two rat models, 9-month-old SD rats and 11-month-old SD rats, were given VAS (40 mg/kg per day) for 4 days, The aqueous fraction of silworm male pupae extract; semi-purified VAS (100 mg/kg per day) for 10 days, respectively. The NOS activities of the following three enzymes were examined: neuronal NO synthase (nNOS), inducible NOS (iNOS), endothelial NOS (eNOS), vascular endothelial growth factor on endothelial cells (VEGF) and anti-inflammation effect of Tumor necrosis factor-α. The results showed increases in the nitric oxide synthase activities. Western blotting of the tissue homogenate showed an increase in the nNOS level in the brain and tongue, and an increase in the endothelial NO synthase (eNOS) level in penis. However, there was little association with VEGF production in HUVEC endothelial cells and no relationship with TNF-α which showed low levels.

Treatment strategies for diabetic patients suffering from erectile dysfunction

Erectile dysfunction is a common complication of diabetes. Clinical practice has no treatment modality specifically designed for the difficult to treat diabetic erectile dysfunction due to the multifactorial and complex pathophysiology of development. PDE type 5 inhibitors are the first-line treatment option. Non-responders should have total and free testosterone checked and testosterone replacement is recommended for hypogonadal patients. For patients who cannot take PDE type 5 inhibitors, or are proven non-responders, the vacuum constriction device continues to serve as a major treatment option. Intracavernosal injection is the most effective medical therapy for diabetic erectile dysfunction despite its high dropout rate. Use of the Medicated Urethral System for Erection to overcome the disadvantages of needle injection is disappointing due to lack of effectiveness. Penile prosthesis will continue to play an important role in diabetic patients with severe erectile dysfunction in coming years.

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.

Endothelial dysfunction in diabetic erectile dysfunction

Erectile dysfunction (ED) is highly prevalent in diabetes mellitus. Pathophysiological mechanisms underlying diabetes-associated ED are in large part due to endothelial dysfunction, which functionally refers to the inability of the endothelium to produce vasorelaxing messengers and to maintain vasodilation and vascular homeostasis. The precise mechanisms leading to endothelial dysfunction in the diabetic vasculature, including the penis, are not yet fully understood. Hyperglycemia affects endothelial nitric oxide synthase activity and nitric oxide production/bioavailability, nitric oxide-independent relaxing factors, oxidative stress, production and/or action of hormones, growth factors and/or cytokines, and generation and activity of opposing vasoconstrictors. Considering recent advances in the field of vascular biology and diabetes, the emphasis in this review is placed on the mechanisms of hyperglycemia-induced endothelial dysfunction in the pathophysiology of diabetes-associated ED.

Penile erection requires association of soluble guanylyl cyclase with endothelial caveolin-1 in rat corpus cavernosum

Erectile dysfunction is caused by a variety of pathogenic factors, particularly impaired formation and action of nitric oxide (NO). NO released from nerve endings and corpus cavernosum endothelial cells plays a crucial role in initiating and maintaining increased intracavernous pressure, penile vasodilatation, and penile erection. Classically, these effects are dependent on cGMP synthesized during activation of soluble guanylyl cyclase (sGC) by NO in smooth muscle cells. The enzyme NO synthase in endothelial cells has been localized to caveolae, small invaginations of the plasma membrane rich in cholesterol. Membrane cholesterol depletion impairs acetylcholine-induced relaxation in arteries attributed to an alteration in caveolar structure. It has been shown that sGC may be activated in endothelial caveolae contributing to vasodilation. We hypothesized that caveolae are the platform for sGC/cGMP signaling in cavernosum smooth muscle eliciting erection. Methyl-beta-cyclodextrin, a pharmacological tool to deplete membrane cholesterol and disassemble caveolae, impaired rat erectile responses in vivo and cavernosum smooth muscle relaxation induced by the NO donor sodium nitroprusside and the sGC activator 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole in vitro. Methyl-beta-cyclodextrin had no effect on cavernosum smooth muscle relaxation induced by NO released upon nerve stimulation or by exogenous cGMP. Furthermore, sGC and caveolin-1, the major coat protein of caveolae, were colocalized in rat corpus cavernosum sinusoidal endothelium. Electron microscopy indicated caveolae disruption in corpus cavernosum treated with methyl-beta-cyclodextrin. In summary, our results provide evidence of compartmentalization of sGC in the caveolae of cavernosal endothelial cells contributing to NO signaling mediating smooth muscle relaxation and erection.