Low serum melatonin levels are associated with erectile dysfunction

Melatonin prevents bone loss in osteoporotic rats with valproic acid treatment by anti-inflammatory and anti-oxidative stress

Melatonin (MEL) has shown positive effects in anti-inflammatory and anti-oxidative stress research. This study investigates whether MEL can positively impact bone loss induced by valproic acid (VPA) in rats. The study examines changes in MC3T3-E1 cell viability and osteogenic potential, along with osteoclast differentiation in RAW264.7 cells in the presence of VPA using CCK-8, ALP staining, AR staining, and TRAP staining. In vitro experiments reveal that VPA-induced inhibition of osteogenic differentiation and promotion of osteoclastic differentiation are linked to increased inflammation and oxidative stress. Furthermore, MEL has demonstrated the ability to reduce oxidative stress and inflammation, boost osteogenic differentiation, and inhibit osteoclast differentiation. Animal experiments confirm that MEL significantly increases SOD2 expression and decreases TNF-α expression, leading to the restoration of impaired bone metabolism, enhanced bone strength, and higher bone mineral density. The combined experimental results strongly suggest that MEL can enhance osteogenic activity in the presence of VPA by reducing inflammation and oxidative stress, impeding osteoclast differentiation, and alleviating bone loss in VPA-treated rat models.

Effect of antidepressants on ejaculation dysfunction in patients with depression and anxiety: A systematic review and network meta-analysis

INTRODUCTION

Antidepressants may lead to a series of sexual adverse effects (SAEs), among which ejaculation dysfunction (EjD) is often overlooked by clinicians. The purpose of the present network meta-analysis was to assist drug adjustment by comparing and ranking the incidence of EjD among various antidepressants.

METHODS

Relevant studies were retrieved from PubMed, Embase, Scopus, Web of Science, ClinicalTrials.gov, and other additional records. Eligible randomized controlled trials (RCTs) assessed the rate of EjD in patients with major depressive disorder (MDD) and anxiety disorder after taking anti-depressants. The incidences of EjD, erectile dysfunction (ED), decreased libido (DL), adverse events (AE), withdrawal due to adverse events (WDAE) and withdrawal due to lack of efficacy (WDLE) were pooled using odds ratio (OR) with their 95% confidence intervals (CI). The values of surface under the cumulative ranking curve (SUCRA) helped to rank the risk of each outcome in different antidepressants.

RESULTS

Thirty RCTs comprising 18,157 patients were included. Results of all node-splitting analysis demonstrated no statistical inconsistency (all P > 0.05). Clomipramine (OR 42.11, 95% CI [9.90, 179.08]), WS5570 (OR 28.99, 95% CI [1.48, 568.97]) and paroxetine (OR 18.63, 95% CI [9.33, 37.23]) had significant risk of EjD comparing to placebo. Additionally, duloxetine (OR 7.37, 95% CI [2.61, 20.78]), clomipramine (OR 5.29, 95% CI [1.72, 16.25]), paroxetine (OR 3.75, 95% CI [1.37, 10.26]) and escitalopram (OR 3.04, 95% CI [1.20, 7.71]) presented higher risk of ED comparing to placebo. Agomelatine, levomilnacipran, vortioxetine, trazodone, vilazodone, fluvoxamine and imipramine exhibited similar incidence of EjD with placebo (all P > 0.05). Besides, trazodone, vilazodone and vortioxetine had the top-five SUCRA values in each of SAEs (EjD, ED and DL), and agomelatine might be alternative in EjD and DL. Considering about AE, WDAE and WDLE, vilazodone appeared to offer more satisfactory performance across all these aspects.

CONCLUSIONS

For patients undergoing SAEs following the administration of antidepressants, trazodone, vortioxetine, vilazodone and agomelatine are alternative antidepressants.

Erectile Dysfunction: Pharmacological Pathways with Understudied Potentials

Erectile dysfunction (ED) is a public health concern worldwide. In the past, it was perceived as a phenomenon attributed to age advancement. However, more individuals are affected every year that do not fall under that age criterion. Epidemiological research revealed that this abnormality has an association with endothelial dysfunction connected to several cardiovascular (CV) risk factors. Currently, ED is interpreted as a clinical marker for future adverse events and not only as a present health issue that negatively affects the quality of life. The management of ED involves lifestyle modifications, therapeutic optimization for comorbid conditions, and pharmacological and psychosexual therapy. Phosphodiesterase type 5 (PDE5) inhibitors are the first-line pharmacological agents to be prescribed for such a condition. Nonetheless, other pharmacological pathways and agents remain underinvestigated or were investigated at some stage. This review aimed to present to future researchers interested in this field with some pharmacological agents that showed favorable effects on a limited number of studies on human subjects or experimental models.

Diagnostic work up: Laboratory and biomarkers

This chapter will focus on the diagnostic work around sexual dysfunction in Parkinson's disease, especially laboratory tests and biomarkers. A number of methods to analyze if sexual dysfunction is caused by neural pathology, vascular dysfunction or other mechanisms are now available. Other methods can be used to differentiate between psychogenic/functional reasons behind sexual dysfunction and organic ones. The role of biomarkers for diagnosis, but also for understanding the reason behind and for counteracting sexual dysfunction is becoming more evident. There is also a rich and increasing number of scales and other instruments available for detecting and quantifying sexual hypo- and hyperactivity. When investigating the reason behind sexual dysfunction in patients with Parkinson's disease comorbidities should also be considered. Finally, early and pronounced sexual dysfunction might in some cases be an indication that differential diagnosis, like Multisystem Atrophy, should be thought about. All these aspects of the diagnostic procedures around sexual dysfunction in Parkinson's disease will be covered in this chapter.

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.

Hypothalamic-Pituitary Diseases and Erectile Dysfunction

Several hormones contribute to ensure penile erection, a neurovascular phenomenon in which nitric oxide plays a major role. Erectile dysfunction (ED), which is defined as the persistent inability to obtain or maintain penile erection sufficient for a satisfactory sexual performance, may be due to arteriogenic, neurogenic, iatrogenic, but also endocrinological causes. The hypothalamus-pituitary axis plays a central role in the endocrine system and represents a fundamental link between the brain and peripheral glands, including gonads. Therefore, the hormonal production of the hypothalamic-pituitary axis can control various aspects of sexual function and its dysregulation can compromise erectile function. In addition, excess and deficiency of pituitary hormones or metabolic alterations that are associated with some pituitary diseases (e.g., Cushing's disease and acromegaly, hypopituitarism) can determine the development of ED with different mechanisms. Thus, the present review aimed to explore the relationship between hypothalamic and pituitary diseases based on the most recent clinical and experimental evidence.

Is Melatonin the Cornucopia of the 21st Century?

Melatonin, an indoleamine hormone produced and secreted at night by pinealocytes and extra-pineal cells, plays an important role in timing circadian rhythms (24-h internal clock) and regulating the sleep/wake cycle in humans. However, in recent years melatonin has gained much attention mainly because of its demonstrated powerful lipophilic antioxidant and free radical scavenging action. Melatonin has been proven to be twice as active as vitamin E, believed to be the most effective lipophilic antioxidant. Melatonin-induced signal transduction through melatonin receptors promotes the expression of antioxidant enzymes as well as inflammation-related genes. Melatonin also exerts an immunomodulatory action through the stimulation of high-affinity receptors expressed in immunocompetent cells. Here, we reviewed the efficacy, safety and side effects of melatonin supplementation in treating oxidative stress- and/or inflammation-related disorders, such as obesity, cardiovascular diseases, immune disorders, infectious diseases, cancer, neurodegenerative diseases, as well as osteoporosis and infertility.

The effect of plasma melatonin levels in the treatment of lifelong premature ejaculation with selective serotonin reuptake inhibitors

The aim of our study was to compare melatonin levels of patients with lifelong premature ejaculation (LPE) (n:60) with healthy controls (n:30) and to investigate the changes of melatonin levels in the treatment with dapoxetine and sertraline. Age, body mass index, duration of marriage, weekly intercourse number, International Index of Erectile Function scores, Intravaginal Ejaculation Latency Time (IELT) and melatonin levels were recorded. LPE patients were divided into two treatment groups. The first group was included 30 patients, who received 60 mg dapoxetine for six weeks, twice a week, an hour before intercourse. The second group received 50 mg of sertraline daily, for six weeks. IELT and melatonin measures were repeated after the treatment. IELT (dapoxetine group: 41.22 ± 21.3 s, sertraline group: 48 ± 23.11 s, control group: 195.54 ± 84.14 s; p < .001) and melatonin levels (dapoxetine group: 5.75 ± 2.04 pg/mL, sertraline group: 5.49 ± 2.88 pg/mL, control group: 13.4 ± 12.09 pg/mL; p < .001) of both LPE groups were significantly lower than control group. Following the six-week sertraline (before: 48 ± 23.11 s, after: 101.01 ± 59.55 s; p < .001) and dapoxetine (before: 41.22 ± 21.3 s, after: 97.39 ± 44.1 s; p < .001) treatments, IELT increased. The melatonin levels increased in the sertraline group (before: 5.49 ± 2.88 pg/mL, after: 10.6 ± 7.37 pg/mL; p < .001). Our results indicate that melatonin levels of LPE patients are lower than levels of healthy volunteers. Furthermore, we found a significant increase in melatonin levels following sertraline treatment.

Melatonin receptor 1A gene polymorphism rs13140012 and serum melatonin in atherosclerotic versus non-atherosclerotic Egyptian ESRD patients: pilot study

Aim

To study the relationship between melatonin levels and Melatonin membrane receptor 1A (MTNR1A) SNP (rs13140012) in end-stage renal disease patients (ESRD) in Alexandria, Egypt on maintenance hemodialysis with or without atherosclerosis.

Materials and methods

40 end-stage renal disease patients on regular hemodialysis were divided into 2 subgroups, one with (n = 20) and one without atherosclerosis (n = 20) and normal subjects (n = 40). Serum melatonin, carotid intimal medial thickness (CIMT) were measured. Melatonin membrane receptor 1A (MTNR1A) SNP (rs13140012) genotyping was done using 5'nuclease Allelic discrimination.

Results

Serum melatonin was significantly lower in ESRD patients [1.6 to 11.30 (pg/mL) with a median of 2.5] than the control group [20.50 to 56.40 (pg/mL) with a median of 35.20]. Serum melatonin was significantly lower in atherosclerotic patients subgroup [1.6–2.50 (pg/mL) with a median value of 2.30] than non-atherosclerotic patients subgroup [2.0–11.30 (pg/mL) with a median of 4.9]. No significant association was found between serum melatonin and (MTNR1A) SNP (rs13140012) (p = 0.633).

Conclusion

These results lead us to suggest that melatonin production is impaired in ESRD patients (included in this pilot study), and this impairment is more evident in atherosclerotic ESRD patients.

Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model

BACKGROUND

Hyperhomocysteinemia (HHcy) has been reported to be strongly correlated with the occurrence of erectile dysfunction (ED), but the mechanisms are not fully understood. Moreover, whether melatonin could be a potential treatment of HHcy-induced ED needs to be elucidated.

AIM

The aim of this study was to investigate the effects of melatonin on HHcy-induced ED and the potential mechanisms via modulating oxidative stress and apoptosis.

METHODS

The Sprague-Dawley (SD) rat model of HHcy was induced by 7% methionine (Met)-rich diets. 36 male SD rats were randomly distributed into 3 groups (n = 12 per group): control group, 7% Met group, and 7% Met + melatonin (Mel; 10 mg/kg, intraperitoneal injection) treatment group. After 4 weeks, the erectile function of all rats was evaluated by electrical stimulation of the cavernous nerve. Histologic and molecular alterations of the corpus cavernosum were also analyzed by immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay, Western blotting, and polymerase chain reaction.

OUTCOMES

HHcy-induced ED rat models were successfully established, and Mel could preserve erectile function mainly through inhibiting oxidative stress via the Erk1/2/Nrf2/HO-1 signaling pathway and suppression of apoptosis.

RESULTS

Erectile function was significantly reduced in the rats with HHcy compared with that in the control group and was ameliorated in the HHcy rats treated with Mel. Compared with the control group, the rats in the HHcy group showed the following: (1) higher levels of total plasma homocysteine; (2) fewer neuronal nitric oxide synthase-positive cells in the corpus cavernous; (3) higher levels of reactive oxygen species and malondialdehyde, higher expression levels of nicotinamide adenine dinucleotide phosphate oxidase, and lower activities of superoxide dismutase, indicating an overactivated oxidative stress; (4) lower expression levels of Erk1/2/Nrf2/HO-1 signaling pathway components; and (5) higher levels of apoptosis, as determined by the expression levels of Bax, Bcl-2, and caspase 3. Mel treatment improved the erectile response, as well as histologic and molecular alterations.

CLINICAL TRANSLATION

Our study on a rodent model of HHcy provided evidence that Mel could be a potential therapeutic method for HHcy-related ED.

CONCLUSIONS

Mel treatment improves erectile function in rats with HHcy probably by potential antioxidative stress activity. This finding provides evidence for a potential new therapy for HHcy-induced ED. Tang Z, Song J, Yu, Z, et al. Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model. J Sex Med 2019;16:1506-1517.