Orall-citrulline supplementation improves erectile function and penile structure in castrated rats

The Effects of a Red-Light Controllable Nitric Oxide Donor, NORD-1, on Erectile Dysfunction in Rats with Streptozotocin Induced Diabetes Mellitus

PURPOSE

Patients with diabetes mellitus (DM) often exhibit refractory erectile dysfunction (ED). Red-light-controllable nitric oxide donor (NORD-1) and red-light irradiation have successfully enhanced erectile function in intact rats. In this study, we investigated whether the combination of NORD-1 and red-light irradiation effectively treated ED in streptozotocin (STZ)-treated rats with DM.

MATERIALS AND METHODS

Seven-week-old male Sprague-Dawley rats were used in this study. Rats in the DM and sham groups received intravenous STZ (50 mg/kg) and saline, respectively. One week after treatment, the blood glucose level of rats in the DM group was >250 mg/dL. Five weeks after the treatment, we performed a functional study by measuring intracavernous pressure (ICP) under cavernous nerve stimulation before and after NORD-1 treatment with and without light irradiation. Additionally, we performed an isometric tension study using the corpus cavernosum of rats treated with NORD-1 or the control compound, SiR650.

RESULTS

The ICP/mean arterial pressure (MAP) ratio was significantly lower in the DM group than in the sham group before and after NORD-1 treatment without light irradiation (both p<0.05). After NORD-1 treatment with light irradiation, the ICP/MAP ratio in the sham and DM groups was significantly enhanced than before and after NORD-1 treatment without light irradiation (all p<0.05). The ICP/MAP ratio in the DM group after NORD-1 with light irradiation was similar to that in the sham group under normal conditions before NORD-1 treatment. Moreover, the systemic blood pressure was not affected by NORD-1 or light irradiation. In the tension study, the corpus cavernosum of rats treated with SiR650 was not changed by red light in the sham or DM groups. However, the rats treated with NORD-1 were strongly relaxed by red light in both groups.

CONCLUSIONS

NORD-1 and red-light irradiation could improve ED in the presence of DM without lowering blood pressure.

Efficacy of a Red-Light Controllable Nitric Oxide Releaser for Neurogenic Erectile Dysfunction: A Study Using a Rat Model of Cavernous Nerve Injury

PURPOSE

Neurogenic erectile dysfunction (ED) is a common side effect of radical prostatectomy (RP) because of cavernous nerve damage. In these patients, the production of nitric oxide (NO), which is important for erection, is decreased in the corpus cavernosum. Therefore, NO donors are useful for post-RP ED. However, short half-life and systemic side effects are problems of NO application in ED therapy. To avert these problems, we developed a red-light controllable NO releaser, NORD-1. This study aimed to investigate the effect of NORD-1 and red-light irradiation on neurogenic ED using a rat model of bilateral cavernous nerve injury (BCNI).

MATERIALS AND METHODS

BCNI and sham operations were conducted on 8-week-old rats. After 4 weeks, erectile function was evaluated using changes in intracavernous pressure (ICP) during electrostimulation of the cavernous nerve. ICP was measured under three conditions; without NORD-1 and red-light irradiation, with NORD-1 and without red-light irradiation, and with NORD-1 and red-light irradiation. SiR650 which absorbs red-light but does not release NO was used for the negative control. After the experiment, localization of NORD-1 was observed using a microscope.

RESULTS

Erectile function in a BCNI rat model was significantly decreased compared to sham-operated rats (p<0.05). After injecting NORD-1 into the penis, erectile function did not change without red-light irradiation. However, the combination of NORD-1 and red-light irradiation significantly improved erectile function (p<0.05) without affecting systemic arterial pressure. In contrast, when SiR650 was used, erectile function did not change in all three conditions. NORD-1 was detected only in the corpus cavernosum and not in the urethra and dorsal vein.

CONCLUSIONS

NORD-1 combined with red-light irradiation is effective for ED induced by cavernous nerve injury. This treatment may have low risks of hypotension and urinary incontinence, and it can replace the current treatment for post-RP ED.

Effects of supplementation with different concentrations of L-citrulline on the plasma amino acid concentration, reproductive hormone concentrations, antioxidant capacity, and reproductive performance of Hu ewes

Context L-citrulline (L-Cit) does not degrade in the rumen and has the ability to form peptide bonds in the body; however, it does not participate in protein synthesis. Aims This study aimed to evaluate the effects of L-Cit on the reproductive performance of Hu ewes. Methods In total, 30 ewes were randomly categorised into five groups. The control group was fed with a basic diet, whereas the Experimental Groups I, II, III, and IV were provided feed supplemented with 5, 10, 15, and 20 g/day of L-Cit respectively. Blood samples of ewes were collected 4 h after feeding on Day 21 of the experiment and before feeding on Day 30. The optimal supplementary feeding dose was selected on the basis of blood biochemical indexes. Overall, ninety 2-year-old ewes were classified into two groups. The control group was fed with a basic diet and the experimental group was fed with a diet supplemented with 10 g/day of L-Cit. After 30 days of supplementary feeding, reproductive performance of ewes was determined. Key results The plasma concentrations of Cit, ornithine, and arginine in ewes increased linearly with an increase in the level of L-Cit supplementation. The plasma concentrations of gonadotropin-releasing hormone, luteinising hormone, and follicle-stimulating hormone in the experimental group increased significantly compared with those in the control group. The plasma total antioxidant capacity and catalase, superoxide dismutase, and glutathione peroxidase in the experimental group were significantly higher than those in the control group, whereas the concentrations of malondialdehyde in all experimental groups were significantly lower than those in the control group. The conception, lambing, and double lambing rates of the experimental group were increased by 28.76%, 15.90%, and 40.21% respectively. Conclusions Supplementation with different doses of L-Cit can improve the concentrations of some plasma amino acids and reproductive hormones as well as antioxidant capacity of ewes. Supplementary feeding with 10 g/day of L-Cit could increase the lambing and double lambing rates of ewes. Implication L-Cit can improve the reproductive performance of ewes.

Effect of L-citrulline Supplementation on Sperm Characteristics and Hormonal and Antioxidant Levels in Blood and Seminal Plasma of Rams

With the aim of providing a theoretical basis for the application of L-citrulline (L-Cit) in animal husbandry, the effects of L-Cit on reproductive hormone levels, antioxidant capacity, and semen quality of rams were studied by feeding them varying doses of L-Cit. A total of 32 rams were randomly divided into four groups with eight rams each. After all rams were trained to donate sperm normally, the control group was fed a basic diet, whereas the experimental groups I, II, and III were provided with feed supplemented with 4, 8, and 12 g/d of L-Cit, respectively.The experiment was conducted for 70 days, during which blood samples were collected from the jugular vein on days 0, 15, 30, 45, and 60, and semen samples were collected on days 0, 20, 40, and 60. In the same group, 100 µL of semen was used to test for quality, The rest of the semen sample and blood samples were centrifuged at 3500 rpm for 15 min, and the supernatant and serum, respectively, were used to determine the levels reproductive hormones and antioxidant indices. Ram semen samples were also collected on day 70 and used to study sperm plasma membrane, substitution, and mitochondrial membrane potential. Compared with the control group, the groups receiving L-Cit showed an increase in sperm concentration and number of linear motile sperm (P < 0.01); decrease in the number of dead sperm (P < 0.01); increase in sperm viability, particularly in groups II and III (P < 0.01); and increase in sperm mitochondrial membrane potential (P < 0.01). Moreover, groups I, II, and III showed significantly higher levels of serum gonadotropin-releasing hormone (GnRH), glutathione peroxidase (GSH-Px), and nitric oxide (NO) (P < 0.01). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased in groups I (P < 0.05), II (P < 0.05), and III (P < 0.01), whereas testosterone (T), catalase (CAT), and superoxide dismutase (SOD) levels increased in groups I and II (P < 0.01). Serum total antioxidant capacity (T-A) increased (P < 0.05), whereas both hydroxyl radical (·OH) and peroxy radical (O2·-) levels decreased (P < 0.01). Compared with the control, all groups had significantly higher SOD and GSH-Px in their seminal plasma (P < 0.01), and groups I, II (P < 0.05 for both), and III (P < 0.01) had higher levels of GnRH and FSH. LH, CAT, and NO levels increased in group I (P < 0.05), II, and III (P < 0.01 for both); malondialdehyde levels decreased in groups I, II (P < 0.05 for both), and group III (P < 0.01); and O2·- levels decreased in groups I, II, and III (P < 0.01). Under our experimental conditions, GnRH, FSH, LH, T, CAT, SOD, T-A, GSH-P_X , and NO levels in the serum and seminal plasma of rams receiving L-Cit increased, whereas Estradiol(E₂ ), O2_· ^- and ·OH levels in the seminal plasma decreased; this improved the semen quality of rams supplemented with L-Cit. Moreover, supplementation with 12 g/d gave the best results.

Oral Testofen, L-Citrulline, Resveratrol, and Caffeine Supplement Drink Improves Sexual Function in Men with Phosphodiesterase 5 Inhibitors: Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study

PURPOSE

Sexuality is very important for men's health. Currently, phosphodiesterase type 5 inhibitors (PDE5i) remain the first-line therapy for erectile dysfunction, and no other oral drugs or drinks are approved and used clinically to treat male libido or orgasm dysfunction. In reference to a pharmaceutical dosage document, growing health consciousness is said to have boosted yearly sales of supplement drinks to more than 170 billion yen (1.58 billion US dollars) in Japan. We have created a supplement drink comprised of testofen, L-citrulline, resveratrol, and caffeine. We hypothesized that our supplement drink would be effective for men with sexual dysfunction, and especially libido dysfunction.

MATERIALS AND METHODS

In this study, men with sexual dysfunction received a placebo drink for 14 days or our supplement drink (testofen, 600 mg/d; L-citrulline, 800 mg/d; resveratrol, 300 mg/d; and caffeine, 40 mg/d) for another 14 days separated by a 7-day washout period. Patients continued on-demand use of PDE5i. The International Index of Erectile Function (IIEF) score and adverse events were assessed.

RESULTS

Twenty patients aged 30-7 years old were enrolled in and concluded the study with no adverse events experienced. The IIEF domains of desire frequency, erection frequency, erection firmness, erection confidence, intercourse satisfaction, ejaculation frequency, orgasm frequency, and overall satisfaction were significantly improved with our supplement drink.

CONCLUSIONS

This is the first study to show that our supplement drink may not only be effective for erection but also for libido, orgasm, and ejaculation.

Enhancement of the RhoA/Rho kinase pathway is associated with stress-related erectile dysfunction in a restraint water immersion stress model

Stress is a risk factor for erectile dysfunction (ED); however, the pathology of stress-induced ED remains unclear. Accordingly, in this study, we investigated the mechanisms of stress-induced ED using a rat model. Ten-week-old male Wistar/ST rats were maintained in a cage filled with water to a height of 2 cm (stress group) or a normal cage (control group). We found that water immersion stress significantly enhanced the contractile response to noradrenaline in the corpus cavernosum (CC) (p < 0.05). Moreover, stress significantly decreased erectile function, as assessed by changes in intracavernous pressure (p < 0.01). In addition, Rho kinase-1 (ROCK-1) protein expression was significantly upregulated under stress conditions (p < 0.05), and phosphorylated myosin light chain (phospho-MLC) levels, contribute to smooth muscle contraction, were also upregulated (p < 0.01). Treatment with fasudil hydrochloride, a Rho kinase inhibitor, for 5 days significantly improved erectile function (p < 0.01) and normalized ROCK-1 and phospho-MLC levels (p < 0.01). Thus, the RhoA/Rho kinase pathway may be associated with stress-induced ED via contraction of CC. Stress also decreased the smooth muscle/collagen ratio of CC (p < 0.01), and fasudil treatment did not alleviate these effects (p = 0.50). These findings suggested that penile fibrosis gradually progressed under stress conditions and that fibrosis may be independent of the RhoA/Rho kinase pathway, implying that longer exposure to stress may promote ED. We conclude that stress-induced ED was caused by contraction of CC mediated by the RhoA/Rho kinase pathway.

Citrulline, Biomarker of Enterocyte Functional Mass and Dietary Supplement. Metabolism, Transport, and Current Evidence for Clinical Use

L-Citrulline is a non-essential but still important amino acid that is released from enterocytes. Because plasma levels are reduced in case of impaired intestinal function, it has become a biomarker to monitor intestinal integrity. Moreover, oxidative stress induces protein citrullination, and antibodies against anti-citrullinated proteins are useful to monitor rheumatoid diseases. Citrullinated histones, however, may even predict a worse outcome in cancer patients. Supplementation of citrulline is better tolerated compared to arginine and might be useful to slightly improve muscle strength or protein balance. The following article shall provide an overview of L-citrulline properties and functions, as well as the current evidence for its use as a biomarker or as a therapeutic supplement.

Alternative Treatment for Erectile Dysfunction: a Growing Arsenal in Men's Health

PURPOSE OF REVIEW

To highlight and review encouraging preliminary studies behind several alternative products and interventions for erectile dysfunction (ED).

RECENT FINDINGS

Alternative treatments for ED are becoming more prevalent with increased consumer interest. "Natural" products are sold online, and numerous clinics offer various off-label and investigational interventions. These alternative treatments have demonstrated varying degrees of efficacy in randomized trials and meta-analyses, but none of these interventions has robust enough evidence to be considered first-line therapy. These treatments may find a role in combination with guideline treatments or may be used in novel penile rehabilitation research protocols. With growing interest in alternative treatment for men's health, an awareness of the literature is imperative for patient counsel. Alternative treatments, like L-arginine, have a growing body of evidence for efficacy in combination with PDE5i, and low-intensity shock wave therapy and stem cell therapy continue to demonstrate encouraging outcomes in ED trials.

Towards Improving Post-SSRI Sexual Dysfunction by Using Nutriceuticals: Lessons from a Case Study

Post-selective serotonin reuptake inhibitors (SSRIs) sexual dysfunction (PSSD) is a new clinical entity occurring after the antidepressant intake, and it is characterized by the fact that patients continue to present sexual side effects after the discontinuation of the drugs. PSSD mainly consists of hypo-anesthesia of the genital area, loss of libido, and erectile dysfunction. Although different management options have been proposed, there is no consensus on the treatment for this syndrome. Herein we report on a young man affected by PSSD who regained sexual functioning after 3-month treatment with EDOVIS, a dietary supplement containing L-citrulline and other commonly used aphrodisiacs. Clinicians should be aware about the possibility of persistent sexual side effects induced by serotoninergic antidepressants and take into considerations the use of nutraceuticals to overcome PSSD.

Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5i) are first-line therapy for most men with erectile dysfunction (ED). If ineffective, vacuum erection devices, intracavernous injections, and penile prosthesis implantation are suitable as second- or third-line therapies. However, very few patients select these therapies. It is critically important to improve erectile function with oral administration of effective agents. Administration of L-citrulline or transresveratrol in animal experiments has been reported to improve erectile function, but few such experiments have been performed on humans with ED.

AIM

We aimed to investigate the efficacy of combination therapy of L-citrulline and transresveratrol in patients with ED despite their use of PDE5i.

METHODS

In this randomized, double-blind, placebo-controlled crossover pilot study, men with ED (Sexual Health Inventory for Men [SHIM] score below 16) despite on-demand use of PDE5i received a placebo for 1 month or the active treatment (L-citrulline 800 mg/day and transresveratrol 300 mg/day) for another month. Patients continued on-demand use of PDE5i.

MAIN OUTCOME MEASURE

The SHIM score, Erection Hardness Score (EHS), Aging Male Symptoms Scale-sexual domain (AMS-SD), and adverse events were examined.

RESULTS

20 patients ages 29-78 years were enrolled, and after 6 men withdrew, 13 concluded the study without adverse events. Mean SHIM score for the active treatment increased significantly (10.96 ± 1.21) compared with baseline (8.32 ± 1.21) and placebo (8.31 ± 1.23) (both P < .05). Mean EHS score for the active treatment (2.56 ± 0.26) also increased from baseline (2.31 ± 0.26), but not significantly (P = .79). Mean AMS-SD score was not significantly different in either group.

CONCLUSION

To our knowledge, this is the first study to show that combination therapy of L-citrulline and transresveratrol is effective for ED treatment in men with added on-demand use of PDE5i. This combination supplement may be added if PDE5i is insufficient. Shirai M, Hiramatsu I, Aoki Y, et al. Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study. Sex Med 2018;6:291-296.

Testosterone Deficiency Causes Endothelial Dysfunction via Elevation of Asymmetric Dimethylarginine and Oxidative Stress in Castrated Rats

BACKGROUND

Testosterone is believed to mediate the penile erectile response by producing adequate nitric oxide; therefore, testosterone deficiency results in erectile dysfunction through decreased nitric oxide bioavailability. However, the mechanisms underlying endothelial dysfunction in testosterone deficiency remain unclear.

AIM

To investigate the mechanism of endothelial dysfunction in a rat model of testosterone deficiency.

METHODS

Rats were distributed into 3 groups: castrated (Cast), castrated and supplemented with testosterone (Cast + T), and sham (Sham). In the Cast + T group, castrated rats were treated daily with subcutaneous testosterone (3 mg/kg daily) for 4 weeks; Sham and Cast rats received only the vehicle.

OUTCOMES

Erectile function using intracavernosal pressure and mean arterial pressure measurements after electrical stimulation of the cavernous nerve, endothelial function using isometric tension, asymmetric dimethylarginine (ADMA) levels using ultra-performance liquid chromatography and tandem mass spectrometry, and inflammatory biomarker expression were performed 4 weeks after the operation.

RESULTS

In the Cast group, the ratio of intracavernosal pressure to mean arterial pressure significantly decreased, acetylcholine-induced relaxation was lower, and serum ADMA, oxidative stress, and inflammation biomarker levels were significantly increased (P < .01). Testosterone injection significantly improved each of these parameters (P < .01).

CLINICAL TRANSLATION

The present results provide scientific evidence of the effect of testosterone deficiency on erectile function and the effect of testosterone replacement therapy.

STRENGTHS AND LIMITATIONS

This study provides evidence of the influence of testosterone deficiency on endothelial function by investigating ADMA and oxidative stress. A major limitation of this study is the lack of a direct link of increased ADMA by oxidative stress to inflammation.

CONCLUSION

Testosterone deficiency increased not only ADMA levels but also oxidative stress and inflammation in castrated rats, which can cause damage to the corpus cavernosum, resulting in erectile dysfunction. Kataoka T, Hotta Y, Maeda Y, Kimura K. Testosterone Deficiency Causes Endothelial Dysfunction via Elevation of Asymmetric Dimethylarginine and Oxidative Stress in Castrated Rats. J Sex Med 2017;14:1540-1548.

Translational Perspective on the Role of Testosterone in Sexual Function and Dysfunction

INTRODUCTION

The biological importance of testosterone is generally accepted by the medical community; however, controversy focuses on its relevance to sexual function and the sexual response, and our understanding of the extent of its role in this area is evolving.

AIM

To provide scientific evidence examining the role of testosterone at the cellular and molecular levels as it pertains to normal erectile physiology and the development of erectile dysfunction and to assist in guiding successful therapeutic interventions for androgen-dependent sexual dysfunction.

METHODS

In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current basic science literature examining the role of testosterone in sexual function and dysfunction.

RESULTS

Testosterone plays an important role in sexual function through multiple processes: physiologic (stimulates activity of nitric oxide synthase), developmental (establishes and maintains the structural and functional integrity of the penis), neural (development, maintenance, function, and plasticity of the cavernous nerve and pelvic ganglia), therapeutically for dysfunctional regulation (beneficial effect on aging, diabetes, and prostatectomy), and phosphodiesterase type 5 inhibition (testosterone supplement to counteract phosphodiesterase type 5 inhibitor resistance).

CONCLUSION

Despite controversies concerning testosterone with regard to sexual function, basic science studies provide incontrovertible evidence for a significant role of testosterone in sexual function and suggest that properly administered testosterone therapy is potentially advantageous for treating male sexual dysfunction.

Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study

Background

Many human studies report that nitric oxide (NO) improves sport performance. This is because NO is a potential modulator of blood flow, muscle energy metabolism, and mitochondrial respiration during exercise. L-Citrulline is an amino acid present in the body and is a potent endogenous precursor of L-arginine, which is a substrate for NO synthase. Here, we investigated the effect of oral L-citrulline supplementation on cycling time trial performance in humans.

Methods

A double-blind randomized placebo-controlled 2-way crossover study was employed. Twenty-two trained males consumed 2.4 g/day of L-citrulline or placebo orally for 7 days. On Day 8 they took 2.4 g of L-citrulline or placebo 1 h before a 4-km cycling time trial. Time taken to complete the 4 km cycle, along with power output/VO₂ ratio (PO/VO₂), plasma nitrite and nitrate (NOx) and amino acid levels, and visual analog scale (VAS) scores, was evaluated.

Results

L-Citrulline supplementation significantly increased plasma L-arginine levels and reduced completion time by 1.5 % (p < 0.05) compared with placebo. Moreover, L-citrulline significantly improved subjective feelings of muscle fatigue and concentration immediately after exercise.

Conclusions

Oral L-citrulline supplementation reduced the time take to complete a cycle ergometer exercise trial.

Trial registration

Current Controlled Trials UMIN000014278.

Castration impairs erectile organ structure and function by inhibiting autophagy and promoting apoptosis of corpus cavernosum smooth muscle cells in rats

OBJECTIVE

The aim of this study was to determine the changes and underlying mechanisms of erectile organ structure and function in castrated rats. In addition, the regulatory effects of an androgen on autophagy and apoptosis in corpus cavernosum smooth muscle cells (CCSMCs), especially the regulatory effect of androgen on the BECN 1-Bcl-2 interaction, were investigated.

METHODS

Male Sprague-Dawley rats were divided into three groups (30/group): control group, castration group, and castration with testosterone supplementation group. The erectile function was examined both in vivo and in vitro, by electric stimulation of the cavernous nerve and corpus cavernosum strip bath test, respectively. Transmission electron microscopy, TUNEL assay, Masson's trichrome staining, immunohistochemistry, and western blotting were performed to determine the levels of autophagy and apoptosis, and the structural changes in corpus cavernosum.

RESULTS

Compared with control group, the castration group showed (1) lower erectile function: lower intracavernosal pressure/mean arterial pressure ratio, lower systolic and diastolic capability of corporal strips, and reduced expressions of eNOS and nNOS; (2) greater fibrosis: decreased smooth muscle/collagen ratio, lower expression of α-SMA, and higher expression of TGF-β1; (3) inhibited autophagy: decreased autophagosomes, lower expressions of BECN1 and LC3-II; and (4) enhanced apoptosis: higher apoptotic index and decreased Bcl-2/Bax ratio. Testosterone supplementation partially improved the effects of castration.

CONCLUSIONS

Castration attenuates erectile function and induces corporeal fibrosis by inhibiting autophagy and promoting apoptosis of CCSMCs in rats. Therefore, our study highlights the important role of androgens in maintaining the integrity of the structure and function of corpus cavernosum in rats through counter-regulation of autophagy and apoptosis, mainly by regulating BECN 1-Bcl-2 interaction.