Long-Term Aspirin Administration Has No Effect on Erectile Function: Evidence from Adult Rats and Ageing Rat Model

Potential causal association between aspirin use and erectile dysfunction in European population: a Mendelian randomization study

Background

Aspirin, as one of the most commonly used drugs, possesses a broad spectrum of therapeutic applications. Presently, the potential association between aspirin usage and the risk elevation of erectile dysfunction (ED) remains inconclusive. The objective of this study employing two-sample Mendelian randomization (MR) was to clarify the causal impact of aspirin use on the risk of ED.

Methods

This study incorporated two sets of Genome-Wide Association Study (GWAS) summary statistics, one for aspirin use (46,946 cases and 286,635 controls) and another for ED (6,175 cases and 217,630 controls) in individuals of European ancestry. The inverse-variance weighted (IVW) method was employed as the primary approach, supplemented by MR-Egger, weighted median, weighted mode, and simple mode to estimate the causal effect of aspirin usage on the risk of ED development. To assess pleiotropy, the MR-PRESSO global test and MR-Egger regression were used. Cochran's Q test was adopted to check heterogeneity, and the leave-one-out analysis was performed to confirm the robustness and reliability of the results.

Results

The causal association between genetically inferred aspirin use and ED was found by using inverse variance weighted (OR = 20.896, 95% confidence interval = 2.077-2.102E+2, P = 0.010). The sensitivity analysis showed that no pleiotropy and heterogeneity was observed. Furthermore, the leave-one-out analysis demonstrated that the findings were not significantly affected by any instrumental variables.

Conclusion

The results of this study highlighted the significance of aspirin use as a predisposing factor for ED and provided further evidence supporting the causal association between aspirin utilization and ED within European populations.

Acetylsalicylic Acid and Mood Disorders: A Systematic Review

The effects of acetylsalicylic acid (ASA) on mood disorders (MD) and on inflammatory parameters in preclinical and clinical studies have not yet been comprehensively evaluated. The aim of this study was to systematically summarize the available knowledge on this topic according to PRISMA guidelines. Data from preclinical and clinical studies were analyzed, considering the safety and efficacy of ASA in the treatment of MD and the correlation of inflammatory parameters with the effect of ASA treatment. Twenty-one studies were included. Both preclinical and clinical studies found evidence indicating the safety and efficacy of low-dose ASA in the treatment of all types of affective episodes in MD. Observational studies have indicated a reduced risk of all types of affective episodes in chronic low-dose ASA users (HR 0.92, 95% CI: 0.88, 0.95, p < 0.0001). An association between ASA response and inflammatory parameters was found in preclinical studies, but this was not confirmed in clinical trials. Further long-term clinical trials evaluating the safety and efficacy of ASA in recurrent MD, as well as assessing the linkage of ASA treatment with inflammatory phenotype and cytokines, are required. There is also a need for preclinical studies to understand the exact mechanism of action of ASA in MD.

Potential Effect of the Circadian Clock on Erectile Dysfunction

The circadian rhythm is an internal timing system, which is generated by circadian clock genes. Because the circadian rhythm regulates numerous cellular, behavioral, and physiological processes, organisms have evolved with intrinsic biological rhythms to adapt the daily environmental changes. A variety of pathological events occur at specific times, while disturbed rhythms can lead to metabolic syndrome, vascular dysfunction, inflammatory disorders, and cancer. Therefore, the circadian clock is considered closely related to various diseases. Recently, accumulated data have shown that the penis is regulated by the circadian clock, while erectile function is impaired by an altered sleep-wake cycle. The circadian rhythm appears to be a novel therapeutic target for preventing and managing erectile dysfunction (ED), although research is still progressing. In this review, we briefly summarize the superficial interactions between the circadian clock and erectile function, while focusing on how disturbed rhythms contribute to risk factors of ED. These risk factors include NO/cGMP pathway, atherosclerosis, diabetes mellitus, lipid abnormalities, testosterone deficiency, as well as dysfunction of endothelial and smooth muscle cells. On the basis of recent findings, we discuss the potential role of the circadian clock for future therapeutic strategies on ED, although further relevant research needs to be performed.

Efficacy of Aspirin for Vasculogenic Erectile Dysfunction in Men: A Meta-Analysis of Randomized Control Trials

One of the major causes of erectile dysfunction (ED) is an endothelial vascular disorder. This meta-analysis is performed to determine the efficacy of aspirin on erectile function in men with vasculogenic ED. For this purpose, CENTRAL, MEDLINE, and reference lists of articles up to November 2019 were searched. Randomized controlled trials (RCTs) were selected that compared aspirin with placebo in men of any ethnicity with vasculogenic ED. A total of 58 trials were retrieved. Finally, two trials of 214 men fulfilled our selection criteria. High selection and detection bias were identified for one trial. The participants showed a significant improvement in erectile function when they took aspirin (mean difference: 5.14, 95% CI [3.89, 6.40], and I² = 0%). Although the present meta-analysis suggested that aspirin has a significant effect on the improvement of erectile function, there were limited RCTs available on this topic and doses of aspirin varied. Additional studies are needed to support findings from this meta-analysis. Aspirin needs to be considered by practitioners when prescribing drugs for vasculogenic ED.

Characteristics of penile growth in pubertal rats and a non-invasive method to lengthen the penis

BACKGROUND

Males with short penises may suffer from sexual dysfunction and psychological problems. However, currently, managing short penis is a huge challenge.

OBJECTIVES

To explore whether inhibition of lysyl oxidase (LOX) activity (anti-LOX) combined with a vacuum device could lengthen the penis of pubertal rat.

MATERIALS AND METHODS

Male rats of different ages were purchased, their exposed penile lengths and weights were measured, and protein expression and lysyl oxidase activity in the corpus cavernosum were analyzed. Fifteen-day-old rats were then purchased and divided into six groups: control, Anti-lysyl oxidase, -200 mm Hg (vacuum device under -200 mm Hg value), -200 mm Hg + Anti-lysyl oxidase, -300 mm Hg, and -300 mm Hg + Anti-lysyl oxidase groups. After the intervention duration of 7 weeks, rats' penile length was measured and erectile function was assessed. The corpus cavernosum was harvested for histopathology and molecular assessments.

RESULTS

Exposed penile length and weight significantly increased with age, especially between 4 and 8 weeks. Both the protein expression and lysyl oxidase activity in corpus cavernosum were the highest at 2 weeks; however, they quickly decreased with age and slowly declined after 8 weeks. Anti-lysyl oxidase significantly increased the penile length by 10.79% over controlled rats, -200 mm Hg + Anti-lysyl oxidase lengthened it by 14.05%, and -300 mm Hg + Anti-lysyl oxidase increased it by 19.84%. Anti-lysyl oxidase significantly reduced lysyl oxidase activity to decrease pyridinoline concentration; however, it did not change desmosine (P = .28), hydroxyproline (P = .14), and total elastin (P = .06) levels. Anti-lysyl oxidase with or without a vacuum device did not diminish erectile function or impair the normal microstructure of corpus cavernosum.

DISCUSSION AND CONCLUSION

The rats' penile growth peaks occurred between 4 and 8 weeks. Anti-lysyl oxidase with a vacuum device promoted penile lengthening by inhibiting pyridinoline production to induce tunica albuginea remodeling. The penile lengthening effect was more obvious in pubertal rats than the adult rats. None of the procedures decreased erectile function.