Genetics and erectile dysfunction: leveraging early foundations for new discoveries

Hormones, Age, and Erectile Dysfunction: Should Routine Testing Be Part of the Initial Evaluation?

Background/Objectives: The aim of this study was to investigate the relationship between age, the severity of erectile dysfunction (ED), and the various hormones that may influence erectile function. Methods: A multicenter cross-sectional study was conducted between January 2015 and December 2023. The study assessed age, sexual function using the IIEF-15 questionnaire, and the levels of total testosterone (TT), free testosterone (FT), FSH, LH, estradiol, prolactin (PRL), and SHBG. Results: A total of 411 patients were included in the study. The mean age of the patients was 63.19 years. The vast majority (91.73%) exhibited some degree of ED. The severity of ED increases with age, ranging from 56.26 years for patients without ED to 73.12 years for those with severe ED. A statistically significant negative correlation was observed between IIEF and age, while a positive correlation was observed between IIEF and serum levels of TT and FT (p < 0.05). Age was significantly correlated with all evaluated hormones (p < 0.01), except estradiol and prolactin. Total testosterone levels progressively decreased with the increase in the severity of erectile dysfunction, from a median of 7.05 ng/mL in patients with normal erectile function to 3.56 ng/mL in those with severe symptoms, remaining above the normal minimum threshold across all groups, whereas free testosterone (FT) levels also declined progressively. All erectile dysfunction groups had median FT levels below the normal minimum threshold. FSH, LH, and SHBG showed an increase with each progressive severity of erectile dysfunction. The multivariate linear regression revealed that IIEF scores are significantly associated with age, TT, and FT levels, while FSH did not present a statistically significant association in this model. Conclusions: Age shows a significant statistical correlation with both the severity of erectile dysfunction and the levels of total testosterone, free testosterone, LH, FSH, and SHBG. Total and free testosterone levels are significantly associated with the severity of erectile dysfunction, with free testosterone median values remaining above the normal minimum threshold in all patients with erectile dysfunction. Therefore, free testosterone should be considered a routine test, alongside total testosterone. In contrast, LH, estradiol, SHBG, and prolactin do not demonstrate any statistical correlation with erectile dysfunction and should not be recommended as routine investigations.

Lipid metabolism and neuromuscular junction as common pathways underlying the genetic basis of erectile dysfunction and obstructive sleep apnea

Erectile dysfunction (ED) incidence is higher in patients with obstructive sleep apnea (OSA). Studies have suggested that ED and OSA may activate similar pathways; however, few have investigated the links between their underlying genotypic profiles. Therefore, we conducted an in-silico analysis to test whether ED and OSA share genetic variants of risk and to identify any molecular, cellular and biological interactions between them. Two gene lists were manually curated through a literature review based on a PUBMED search, which resulted in one gene list associated with ED (total of 205 genes) and the other with OSA (total of 2622 genes). Between those gene sets, 35 were common for both lists (Fisher exact test, p-value = 0.027). The Protein-protein interaction (PPI) analysis using the intersect list as input showed that 3 of them had direct interactions (LPL, DGKB and PLCB1). In addition, the biological function of the genes contained in the intersect list suggested that pathways related to lipid metabolism and the neuromuscular junction were commonly found in the genetic basis of ED and OSA. From the shared genes between both conditions, the biological pathways highlighted in this study may serve as preliminary findings for future functional investigations on OSA and ED association.

Role of Nutraceuticals in Treating Erectile Dysfunction via Inhibition of Phosphodiesterase-5 Enzyme: A Mini Review

Erectile Dysfunction (ED) is a prevalent sexual health condition affecting a significant portion of the male population worldwide. The conventional therapeutic approaches for ED often involve the use of pharmaceutical agents targeting the phosphodiesterase-5 (PDE5) enzyme. Currently, treatment with PDE-5 inhibitors is the standard approach for ED, and four PDE-5 inhibitors, namely sildenafil, vardenafil, tadalafil, and avanafil, are in use. However, these pharmaceutical interventions may be associated with adverse effects and limitations. As a result, there has been a growing interest in exploring alternative and complementary treatment options for ED, such as nutraceuticals, which are bioactive compounds derived from natural sources. Nutraceuticals, which include vitamins, minerals, herbs, and other dietary supplements, have gained popularity for their potential health benefits. Certain nutraceuticals have demonstrated the ability to modulate various physiological pathways, including those involved in erectile function. A notable mechanism of action is the inhibition of the PDE5 enzyme, which plays a pivotal role in the regulation of cGMP levels. By inhibiting PDE5, nutraceuticals can promote the accumulation of cGMP, leading to enhanced penile blood flow and improved erectile function. A comprehensive analysis of the literature showcases various nutraceutical agents, including plant-derived compounds like flavonoids, polyphenols, and amino acids which have exhibited PDE5 inhibitory effects. Mechanistic insights into their action involve modulation of NO release, cGMP elevation, and relaxation of penile smooth muscles, all critical factors for achieving and sustaining erections. This review focuses on elucidating the role of nutraceuticals in treating erectile dysfunction through the inhibition of the PDE5 enzyme.

Erectile Dysfunction: Causes, Diagnosis and Treatment: An Update

Erectile Dysfunction (ED) is defined as "recurrent and persistent inability, partial or complete, to achieve or maintain an erection firm enough for satisfactory sexual intercourse in the presence of proper erotic stimuli"; the concept of ED replaced the previous definition of "impotence" [...].

Transcription factor gene Pea3 regulates erectile function during copulation in mice

Male mice with homozygous loss of function mutations of the transcription factor gene Pea3 (Pea3 null) are infertile due to their inability to inseminate females, however the specific deficits in male sexual behaviors that drive this phenotype are unknown. Here, the copulatory behavior of male mice (Pea3 null and control) with hormonally primed ovariectomized females was monitored via high-speed and high-resolution digital videography to assess for differences in female-directed social behaviors, gross sexual behaviors (mounting, thrusting), and erectile and ejaculatory function. Pea3 null male mice exhibit greatly reduced erectile function, with 44% of males displaying no visible erections during copulation, and 0% achieving sustained erections. As such, Pea3 null males are incapable of intromission and copulatory plug deposition, despite displaying largely normal female-directed social behaviors, mounting behaviors, and ejaculatory grasping behavior. Additionally, the organization and timing of thrusting behaviors is impaired in Pea3 null males. Our results show that the transcription factor gene Pea3 regulates the ability to achieve and maintain erections during copulation in mice.