Effects of phosphodiesterase-5 inhibitors on sperm parameters and fertilizing capacity

The aim of this review study is to elucidate the effects that phosphodiesterase 5 (PDE5) inhibitors exert on spermatozoa motility, capacitation process and on their ability to fertilize the oocyte. Second messenger systems such as the cAMP/adenylate cyclase (AC) system and the cGMP/guanylate cyclase (GC) system appear to regulate sperm functions. Increased levels of intracytosolic cAMP result in an enhancement of sperm motility and viability. The stimulation of GC by low doses of nitric oxide (NO) leads to an improvement or maintenance of sperm motility, whereas higher concentrations have an adverse effect on sperm parameters. Several in vivo and in vitro studies have been carried out in order to examine whether PDE5 inhibitors affect positively or negatively sperm parameters and sperm fertilizing capacity. The results of these studies are controversial. Some of these studies demonstrate no significant effects of PDE5 inhibitors on the motility, viability, and morphology of spermatozoa collected from men that have been treated with PDE5 inhibitors. On the other hand, several studies demonstrate a positive effect of PDE5 inhibitors on sperm motility both in vivo and in vitro. In vitro studies of sildenafil citrate demonstrate a stimulatory effect on sperm motility with an increase in intracellular cAMP suggesting an inhibitory action of sildenafil citrate on a PDE isoform other than the PDE5. On the other hand, tadalafil's actions appear to be associated with the inhibitory effect of this compound on PDE11. In vivo studies in men treated with vardenafil in a daily basis demonstrated a significantly larger total number of spermatozoa per ejaculate, quantitative sperm motility, and qualitative sperm motility; it has been suggested that vardenafil administration enhances the secretory function of the prostate and subsequently increases the qualitative and quantitative motility of spermatozoa. The effect that PDE5 inhibitors exert on sperm parameters may lead to the improvement of the outcome of assisted reproductive technology (ART) programs. In the future PDE5 inhibitors might serve as adjunct therapeutical agents for the alleviation of male infertility.

Effects of phosphodiesterase-5 inhibitors on Leydig cell secretory function in oligoasthenospermic infertile men: a randomized trial

OBJECTIVE

to evaluate the effects of phosphodiesterase-5 inhibitors (PDE5-i) on Leydig cell secretory function (LCSF).

PATIENTS AND METHODS

in all, 75 men with oligoasthenospermia were treated daily for 12 weeks with either vardenafil (23 men, group A), sildenafil (25 men, group B) or l-carnitine (26 men, group C); a further group of 22 men with oligoasthenospermia (group D) received no treatment. Serum levels of insulin-like-3 peptide (INSL3) were evaluated before and after the end of the treatment in each of groups A, B and C, respectively. Serum INSL3 levels were measured in each participant of group D before and after the 12-week experimental period.

RESULTS

within group A and B, the peripheral serum mean INSL3 concentration, sperm concentration, percentage of motile spermatozoa, and percentage of morphologically normal spermatozoa were significantly greater after PDE5-i treatment than before.

CONCLUSION

we suggest that PDE5-i enhances LCSF, as the mean INSL3 concentration was significantly greater after PDE5-i administration than before, within groups A and B. This enhancement in LCSF might contribute to the increase in sperm concentration and sperm motility after administration of PDE5-i.

The Sertoli cell as the orchestra conductor of spermatogenesis: spermatogenic cells dance to the tune of testosterone

Spermatogenesis is contingent upon hormones and growth factors acting through endocrine and paracrine pathways either in vivo or in vitro. Sertoli cells (SCs) furnish essential factors for the successful advancement of spermatogenesis and spermiogenesis. Moreover, receptors for follicle stimulating hormone (FSH) and testosterone, which are the main hormonal regulators of spermatogenesis, are identified on SCs. Testosterone, FSH and luteinizing hormone are known to determine the destiny of germ cells and in their absence germ cells undergo apoptosis. Bcl-2 family proteins determine one signaling pathway which seems to be crucial for the homeostasis of male gametes. In addition to paracrine signals, germ cell development also relies on signals generated by SCs via direct membrane contact. The regulatory peptide somatostatin has an important role in the regulation of the proliferation of the male germ cells. Activin A, follistatin and FSH control germ cell development. In vitro culture systems have provided initial evidence supporting the achievement of the completion of the first and second male meiotic division in vitro. This review article provides an overview of the literature regarding the hormonal pathways governing spermatogenesis and spermiogenesis.

Antioxidant Supplementation on Male Fertility-A Systematic Review

Our aim was to review the current literature regarding the effect of antioxidant supplementation (AS) on male fertility parameters, as AS is commonly used to treat male infertility due to the availability and affordability of antioxidants in many parts of the world.

MATERIALS AND METHODS

PubMed, Medline, and Cochrane electronic bibliographies were searched using the modified Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) guidelines to evaluate studies on the benefit of antioxidant therapy on infertile men. Results were analyzed regarding the following aspects: (a) ingredient and dose; (b) potential mechanism of action and rationale for use; and (c) effect on various reported outcomes.

RESULTS

Thus, 29 studies found a substantial positive effect of AS on outcomes of assisted reproductive therapy (ART), WHO semen parameters, and live-birth rate. Carnitines, Vitamin E and C, N-acetyl cysteine, coenzyme Q10, selenium, zinc, folic acid, and lycopene were beneficial ingredients. Nevertheless, some studies did not show a substantial change in one or more factors.

CONCLUSION

AS seems to have a positive effect on male fertility. Environmental factors may play an increasing role in fertility. Further studies are needed to determine the optimal AS combination and the influence of environmental factors.

Is there a role for PDE5 inhibitors in the management of male infertility due to defects in testicular or epididymal function?

This review study refers to the possibility to employ PDE5 inhibitors as an adjunct tool for the therapeutic management of male infertility. The literature tends to suggest that PDE5 inhibitors enhance the Leydig cell secretory function and play a role in the regulation of the contractility of the tunica albuginea and the epididymis. In addition, the literature suggests that PDE5 inhibitors increase the prostatic secretory function that results in an improvement in sperm motility in several cases. Some studies additionally demonstrate a role of PDE5 inhibitors in the regulation of sperm capacitation process. Additional placebo-controlled, randomized, blind studies are necessary to unequivocally suggest a therapeutic role of PDE5 inhibitors in the alleviation of semen disorders and male infertility.

Administration of Antioxidants in Infertile Male: When it may have a Detrimental Effect?

BACKGROUND & OBJECTIVE

Significant advances in the field of male infertility have been witnessed during the last years. Given the well-known detrimental effects of reactive oxygen species (ROS), the administration of antioxidants has emerged as a promising solution for oxidative stress (OS)-induced male infertility. Nevertheless, this perception seems largely oversimplified, and the existing literature fails to recognize a notable superiority of the excessive use of these widely available nutritional compounds. Taking into consideration that several trials have shed light on the so-called "antioxidant paradox" phenomenon, we recognize that over-the-counter consumption of such supplements might be harmful.

METHODS

The relevant studies indexed in PubMed, Google Scholar and Scopus databases, published until September 2019 were identified and reported.

CONCLUSION

In this setting, we acknowledge that there is an urgent need for more elaborate studies in the future that will efficiently elucidate the risks and benefits of antioxidants on semen parameters and their impact on fertility potential.

Therapeutic Effects of Micronutrient Supplements on Sperm Parameters: Fact or Fiction?

BACKGROUND

Despite the limited evidence about the effect of micronutrient supplementation on the semen quality, many micronutrient supplements have been used to improve male fertility. Approximately, 40%- 50% of male infertility cases in general and up to 80% in men with idiopathic infertility cases are caused by oxidative stress and decreased level of seminal total antioxidant capacity.

OBJECTIVE

To investigate the beneficial effects of micronutrient supplementation on sperm concentration, motility and morphology.

METHODS

A PubMed, Google Scholar, Embase data, Web of Science and Cochrane Library database extensive research of the randomized controlled studies utilizing micronutrient vitamins and supplements was performed.

RESULTS

The existent international literature is rather heterogeneous and a definitive is difficult to be drawn. Several micronutrients have beneficial effects on sperm parameters. Rational use of micronutrients might be helpful for infertile patients.

CONCLUSION

Further randomized, controlled clinical trials are required to elucidate the efficacy and safety of micronutrients and propose proper protocols for their use. A well-rounded, balanced diet is more preferable than the widespread use of micronutrient supplements beyond the recommended doses. Future studies should concern the pregnancy rate as a primary outcome in their designs. Further research should be done to determine the appropriate antioxidant compounds, the duration of the treatment, as well as a certain dose of antioxidants in clinical practices. The pre-treatment evaluation of the seminal oxidative status is also an important parameter to proceed with micronutrient supplementation without the risk of reductive stress. Under these conditions, supplements could support the quality of sperm and help to alleviate male infertility.

The Effect of Low-Intensity Extracorporeal Shockwave Treatment on the Urinary Bladder in an Experimental Diabetic Rat Model

Purpose

Preclinical data increasingly support an impact of low-intensity extracorporeal shockwave therapy (Li-ESWT) on the bladder. We investigated the molecular effects of Li-ESWT on the bladder of a streptozotocin-induced diabetic rat model.

Methods

Fifteen 8-week-old male Wistar rats were randomized into 3 groups: a control group (n=5), a group of diabetic rats without treatment (diabetes mellitus [DM], n=5) and a group of diabetic rats treated with Li-ESWT (DM-ESWT, n=5). A single intraperitoneal dose of streptozotocin (60 mg/kg) was used to induce diabetes. Twenty days after diabetes induction, each rat in the DM-ESWT group received 300 shockwaves with an energy flux density of 0.09 mJ/mm². Sessions were repeated 3 times/week for 2 weeks, followed by a 2-week washout period. Total RNA from bladder tissue was extracted, cDNA was synthesized, and quantitative real-time polymerase chain reaction was performed to analyze the expression pattern of transient receptor potential vanilloid 1 (Trpv1), interleukin-1β (Il1b), and the muscarinic receptors M1, M2, and M3 (Chrm1, Chrm2, and Chrm3).

Results

The expression of Trpv1, Il1b, and Chrm2 genes was significantly different between the 3 groups (P=0.002, P<0.0001, and P=0.011, respectively; 1-way analysis of variance). In the DM group, the expression of all genes was higher than in the control group, but statistical significance was observed only for Trpv1 and Il1b (P=0.002 and P<0.0001, respectively). Li-ESWT significantly reduced the expression of Il1b and Chrm2 (P=0.001 and P=0.011, respectively), whereas a nonsignificant tendency for reduced expression was noted for Trpv1 (P=0.069).

Conclusions

The induction of diabetes was associated with increased expression of genes related to mechanosensation, inflammation/ischemia, and contraction in the rat bladder. Li-ESWT reduced the expression of IL1b, Chrm2, and to a lesser extent Trpv1 toward the control levels, suggesting the therapeutic potential of this treatment modality for diabetic cystopathy.

Effect of testosterone replacement treatment on constitutional and sexual symptoms in type 2 diabetic men: need for rules

In a recent publication, Gianatti and colleagues investigated the effect of testosterone treatment in obese, aging men with type 2 diabetes (T2D) with mild to moderate symptoms, a modest reduction in testosterone levels, mild to moderate aging male symptoms, and erectile dysfunction. [1] The authors could not show any significant improvement in constitutional or sexual symptoms in this group of men. This randomized double-blind, parallel, and placebo-controlled trial among other critically emphasizes the increased testosterone prescriptions worldwide and together with other corroborating or contradictory studies awakes the need for guidelines in the androgen replacement treatment.

PDE5 inhibitors and male reproduction: Is there a place for PDE5 inhibitors in infertility clinics or andrology laboratories?

The objective of this review study is to evaluate the therapeutic role of PDE5 inhibitors (PDE5is) in the amelioration of oligoasthenospermia in infertile males. PDE5is have a beneficial influence on the secretory function of the Leydig and Sertoli cells, the biochemical environment within the seminiferous tubule, the contractility of the testicular tunica albuginea, and the prostatic secretory function. In several studies, the overall effect of sildenafil and vardenafil increased quantitative and qualitative sperm motility. Furthermore, some studies indicate that PDE5is influence positively the sperm capacity to undergo capacitation under biochemical conditions that are known to induce the sperm capacitation process. Additional research efforts are necessary in order to recommend unequivocally the usage of sildenafil, vardenafil, or avanafil for the alleviation of male infertility.