Androgen deficiency impairs erectile function in rats through promotion of corporal fibrosis

Autophagy in erectile dysfunction: focusing on apoptosis and fibrosis

ABSTRACT

In most types of erectile dysfunction, particularly in advanced stages, typical pathological features observed are reduced parenchymal cells coupled with increased tissue fibrosis. However, the current treatment methods have shown limited success in reversing these pathologic changes. Recent research has revealed that changes in autophagy levels, along with alterations in apoptosis and fibrosis-related proteins, are linked to the progression of erectile dysfunction, suggesting a significant association. Autophagy, known to significantly affect cell fate and tissue fibrosis, is currently being explored as a potential treatment modality for erectile dysfunction. However, these present studies are still in their nascent stage, and there are limited experimental data available. This review analyzes erectile dysfunction from a pathological perspective. It provides an in-depth overview of how autophagy is involved in the apoptotic processes of smooth muscle and endothelial cells and its role in the fibrotic processes occurring in the cavernosum. This study aimed to develop a theoretical framework for the potential effectiveness of autophagy in preventing and treating erectile dysfunction, thus encouraging further investigation among researchers in this area.

Sulfur dioxide (SO2) donors, a new gasotransmitter, improve erectile dysfunction after castration in a rat model

BACKGROUND

Androgen deprivation is associated with erectile dysfunction (ED). In different animal models, sulfur dioxide (SO2) donors Na2SO3 and NaHSO3 reduced oxidative stress, fibrosis, and inflammation which contribute to the pathogenesis of androgen deprivation-induced ED, however the effect of SO2 donors on ED in castrated rats were not known.

OBJECTIVE

To investigate the therapeutic effect of SO2 donors, Na2SO3/NaHSO3, on ED in castrated rat model.

MATERIALS AND METHODS

Sprague-Dawley male rats (n = 30) were divided into four groups; control, control-treated with Na2SO3/NaHSO3, castrated, and castrated-treated with Na2SO3/NaHSO3. Castration was induced by bilateral scrotal incisions. Four weeks after castration, rats were treated with Na2SO3/NaHSO3 (0.54/0.18 mmol/kg) intraperitoneally (i.p.) for 4 weeks. Intracavernosal pressure/mean arterial pressure ratio (ICP/MAP) and total ICP were measured to evaluate in vivo erectile responses in cavernosal tissue. In vitro relaxant and contractile responses were measured in all groups. Endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), PI3 kinase p85 alpha + gamma (PI3K), protein kinase B (AKT 1/2/3), cysteine dioxygenase-1 (CDO), and aspartate aminotransferase (AAT) expressions and localizations were evaluated by Western blotting and immunohistochemical staining. The smooth muscle/collagen ratio was evaluated by Masson's trichrome staining.

RESULTS

Prostate (p < 0.001) and penis weight (p < 0.001), total serum testosterone (T) level (p < 0.001), and in vivo erectile responses (p < 0.001 at 7.5 and 5 V, p < 0.05 at 2.5 V for ICP/MAP and total ICP) of castrated rats were decreased compared with control. SO2 donors improved reduced ICP/MAP ratio and total ICP (p < 0.01 at 7.5, 5, and 2.5 V for ICP/MAP and total ICP) nitrergic (p < 0.05 at 20 Hz), and endothelium-independent relaxation (p < 0.05 at 1 nM, p < 0.01 at 10 µM and 100 µM) in the castrated group. Decreased eNOS (p < 0.01) and AKT (p < 0.001) protein expressions in the castrated group were normalized by SO2. SO2 donors partially restored the reduced smooth muscle/collagen ratio in the castrated group (p < 0.001). The expressions and locations of nNOS, PI3K, CDO, and AAT proteins in penile tissue did not alter among all groups (p > 0.05).

DISCUSSION AND CONCLUSION

SO2 donors significantly improve erectile functions and relaxation responses in a castrated rats via ameliorating endothelial damage and fibrosis. Androgen deprivation inhibits the AKT/eNOS signaling while SO2 activates this pathway. SO2 donors may be promising for the treatment of ED in hypoandrogenic men.

MicroRNAs as diagnostic biomarkers in diabetes male infertility: a systematic review

This study conducts an in-depth review of the correlation between testis tissue changes and circulating microRNAs (miRNA) in diabetes-induced male reproductive complications, drawing upon both animal and clinical studies. The original articles published in English that specifically investigate miRNAs linked to male infertility in humans or animals with either type I or ΙΙ diabetes mellitus were included. The relevant articles were gathered from the PubMed, Google Scholar, Cochrane Library, and ScienceDirect databases. The quality of study was assessed utilizing the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Prevalence Studies. We collected an overall number of 1989 citations relating to our research subject. Following the elimination of articles based on the criteria, a total of 20 papers were included in the study. Aberrant expression profiles of 25 miRNAs were identified in diabetes associated with male reproductive issues, with 15 miRNAs exhibiting increased expression and 10 miRNAs showing decreased expression. Among the chosen publications, eighteen were identified as low-risk and two were classed as moderate quality. The dysregulated miRNAs were linked to testicular injury, disrupted steroid production, decreased sperm development and quality, and erectile dysfunction. The results demonstrate that the miRNA-mRNA network is linked to the pathological progression of diabetic testicular damage or erectile dysfunction. From a therapeutic perspective, the identification of circulating miRNAs could be beneficial in the timely identification and prevention of diabetes problems, such as diabetes-induced male infertility. Among all signaling pathways influenced by modified miRNAs, the Bax-caspase-3, MAPK, PI3K-Akt, and eNOS-cGMP-PKC were the main deregulated pathways.

Polystyrene nanoplastics exposure causes erectile dysfunction in rats

Polystyrene nanoplastics (PS-NPs), emerging and increasingly pervasive environmental contaminants, have the potential to cause persistent harm to organisms. Although previous reports have documented local accumulation and adverse effects in a variety of major organs after PS-NPs exposure, the impact of PS-NPs exposure on erectile function remains unexplored. Herein, we established a rat model of oral exposure to 100 nm PS-NPs for 28 days. To determine the best dose range of PS-NPs, we designed both low-dose and high-dose PS-NPs groups, which correspond to the minimum and maximum human intake doses, respectively. The findings indicated that PS-NPs could accumulate within the corpus cavernosum and high dose but not low dose of PS-NPs triggered erectile dysfunction. Moreover, the toxicological effects of PS-NPs on erectile function include fibrosis in the corpus cavernous, endothelial dysfunction, reduction in testosterone levels, elevated oxidative stress and apoptosis. Overall, this study revealed that PS-NPs exposure can cause erectile dysfunction via multiple ways, which provided new insights into the toxicity of PS-NPs.

Stereological comparison of smooth muscle, collagen, and elastic fibers of the clitoris and glans penis in young adults

OBJECTIVE

To compare the collagen, elastic fibers, and smooth muscle content of the clitoris and the glans penis in young adults.

MATERIALS AND METHODS

The clitoris and the glans penis of six women and six men (mean age 25±3) who died as a result of accidents were excised. The samples were placed under a formaldehyde solution and histologically processed. Masson's trichrome and Weigert's resorcin-fuchsin stain was used to highlight the elastic fibers, smooth muscle, and collagen. Stereological analysis was conducted in 5 random fields of 5 slides for each sample. For statistical analysis, the unpaired t-test was used to compare values between groups, and a value of P<0.05 was considered as significant for all analyses.

RESULTS

Stereology revealed a mean smooth muscle content of 35.84±6.46% and 31.64±4.74% for the clitoris and glans penis, respectively, while it also revealed collagen content of 26.11±7.41% and 28.44±3.55% and elastic fibers content of 24.12±4.34% and 30.97±6.13% for the clitoris and glans penis, respectively. The statistical analysis showed no significant differences between them.

CONCLUSION

Regardless of anatomical differences, the volumetric density of collagen, elastic fibers, and smooth muscle were similar for the clitoris and glans penis in young adults, a feature possibly explained by their embryology.

A visualization system for erectile vascular dynamics

Erection is an essential process which requires the male penis for copulation. This copulatory process depends on the vascular dynamic regulation of the penis. The corpus cavernosum (CC) in the upper (dorsal) part of the penis plays a major role in regulating blood flow inside the penis. When the CC is filled with blood, the sinusoids, including micro-vessels, dilate during erection. The CC is an androgen-dependent organ, and various genital abnormalities including erectile dysfunction (ED) are widely known. Previous studies have shown that androgen deprivation by castration results in significantly decreased smooth muscles of the CC. Experimental works in erectile biology have previously measured intracavernosal penile pressure and mechanical tension. Such reports analyze limited features without assessing the dynamic aspects of the erectile process. In the current study, we established a novel explant system enabling direct visual imaging of the sinusoidal lumen to evaluate the dynamic movement of the cavernous space. To analyze the alternation of sinusoidal spaces, micro-dissected CC explants by patent blue dye injection were incubated and examined for their structural alternations during relaxation/contraction. The dynamic process of relaxation/contraction was analyzed with various external factors administered to the CC. The system enabled the imaging of relaxation/contraction of the lumens of the sinusoids and the collagen-containing tissues. Histological analysis on the explant system also showed the relaxation/contraction. Thus, the system mimics the regulatory process of dynamic relaxation/contraction in the erectile response. The current system also enabled evaluating the erectile pathophysiology. In the current study, the lumen of sinusoids relaxed/contracted in castrated mice similarly with normal mice. These results suggested that the dynamic erectile relaxation/contraction process was similarly retained in castrated mice. However, the system also revealed decreased duration time of erection in castrated mice. The current study is expected to promote further understanding of the pathophysiology of ED, which will be useful for new treatments in the future. Hence, the current system provides unique information to investigate the novel regulations of erectile function, which can provide tools for analyzing the pathology of ED.

The synergistic effects of testosterone and phophodiesterase-5 inhibitor combination on oxidative stress markers, matrix metalloproteinases and oxidative DNA damage: A randomized controlled experimental study

PURPOSE

To investigate the effects of combined tadalafil and testosterone usage on oxidative stress, DNA damage and MMPs in testosterone deficiency.

METHODS

Fifty rats were randomly divided into 5 groups (group-1: sham group-placebo, group-2: bilateral orchiectomy (ORX), group-3: bilateral ORX+tadalafil, group-4: bilateral ORX+testosterone, group-5: bilateral ORX+tadalafil+testosterone). Group-3 received tadalafil (5mg/kg/day, oral). Group-4 was administered testosterone undecanoate (100mg/kg i.m., single dose). Group-5 was administered a combination of tadalafil and testosterone undecanoate. All groups were compared with regard to serum nicotinamide adenine dinucleotide phosphate oxidase-4 (NOX-4), total thiol, matrix metalloproteinase-2 (MMP-2), MMP-3 and MMP-9, tissue inhibitor of metalloproteinases-1 (TIMP-1) and TIMP-2 and 8-hydroxy-2-deoxy guanosine (8-OHdG) levels.

RESULTS

Total thiol levels of group-2 were significantly lower than the other groups and thiol levels were higher in group-1 and group-5 than in the other groups. NOX4, MMP2 and 9 levels in group-2 were higher than in the other groups. MMP-9 levels in group-5 were lower than in groups 3 and 4 (p=.001). The level of 8-OHdG in groups 2 and 3 was higher than in the other groups (p=.001). In correlation analysis, 8-OHdG, MMP2, and 9 levels were negatively correlated with total thiol, whereas NOX4 and 8-OHdG levels were positively correlated with MMPs values.

CONCLUSIONS

The combination of testosterone with PDE-5 inhibitor suppresses MMP-9 levels and increases total thiol levels better than testosterone alone and tadalafil alone. Therefore, testosterone can be considered for use with PDE-5 inhibitor from the initial stage in case of testosterone deficiency.

Testosterone replacement therapy and erectile dysfunction

Testosterone (T) deficiency and erectile dysfunction (ED) are independently functionally and socially impairing, and their concurrence in men can be challenging to treat. Successful management requires an understanding of the mechanisms through which T underlies normal erectile function. While the literature elucidating some of these mechanisms is vast (e.g., androgen regulation of the activity of nitric oxygen synthase and phosphodiesterase type 5) for others it is scarce (e.g., catalysts of castration-induced corporal fibrosis). The randomized controlled trial data for the efficacy of T replacement as mono- or combination therapy to treat ED has been conflicting. Positive results were frequently not clinically meaningful. Meta-analyses have been helpful in illuminating trends that seem to be promising. Consensus is still lacking in several areas, such as the threshold of low T severity for which replacement therapy is most beneficial; the timing for initiating combination therapy; and the duration of treatment.

New Insight into Molecular and Hormonal Connection in Andrology

Hormones and cytokines are known to regulate cellular functions in the testes. These biomolecules induce a broad spectrum of effects on various level of spermatogenesis, and among them is the modulation of cell junction restructuring between Sertoli cells and germ cells in the seminiferous epithelium. Cytokines and androgens are closely related, and both correct testicular development and the maintenance of spermatogenesis depend on their function. Cytokines also play a crucial role in the immune testicular system, activating and directing leucocytes across the endothelial barrier to the inflammatory site, as well as in increasing their adhesion to the vascular wall. The purpose of this review is to revise the most recent findings on molecular mechanisms that play a key role in male sexual function, focusing on three specific molecular patterns, namely, cytokines, miRNAs, and endothelial progenitor cells. Numerous reports on the interactions between the immune and endocrine systems can be found in the literature. However, there is not yet a multi-approach review of the literature underlying the role between molecular patterns and testicular and sexual function.

Role of Glucose-Lowering Medications in Erectile Dysfunction

Erectile dysfunction (ED) is a long-term complication of type 2 diabetes (T2D) widely known to affect the quality of life. Several aspects of altered metabolism in individuals with T2D may help to compromise the penile vasculature structure and functions, thus exacerbating the imbalance between smooth muscle contractility and relaxation. Among these, advanced glycation end-products and reactive oxygen species derived from a hyperglycaemic state are known to accelerate endothelial dysfunction by lowering nitric oxide bioavailability, the essential stimulus of relaxation. Although several studies have explained the pathogenetic mechanisms involved in the generation of erectile failure, few studies to date have described the efficacy of glucose-lowering medications in the restoration of normal sexual activity. Herein, we will present current knowledge about the main starters of the pathophysiology of diabetic ED and explore the role of different anti-diabetes therapies in the potential remission of ED, highlighting specific pathways whose activation or inhibition could be fundamental for sexual care in a diabetes setting.

Dynamic erectile responses of a novel penile organ model utilizing TPEM†

Male penis is required to become erect during copulation. In the upper (dorsal) part of penis, the erectile tissue termed corpus cavernosum (CC) plays fundamental roles for erection by regulating the inner blood flow. When blood flows into the CC, the microvascular complex termed sinusoidal space is reported to expand during erection. A novel in vitro explant system to analyze the dynamic erectile responses during contraction/relaxation is established. The current data show regulatory contraction/relaxation processes induced by phenylephrine (PE) and nitric oxide (NO) donor mimicking dynamic erectile responses by in vitro CC explants. Two-photon excitation microscopy (TPEM) observation shows the synchronous movement of sinusoidal space and the entire CC. By taking advantages of the CC explant system, tadalafil (Cialis) was shown to increase sinusoidal relaxation. Histopathological changes have been generally reported associating with erection in several pathological conditions. Various stressed statuses have been suggested to occur in the erectile responses by previous studies. The current CC explant model enables to analyze such conditions through directly manipulating CC in the repeated contraction/relaxation processes. Expression of oxidative stress marker and contraction-related genes, Hypoxia-inducible factor 1-alpha (Hif1a), glutathione peroxidase 1 (Gpx1), Ras homolog family member A (RhoA), and Rho-associated protein kinase (Rock), was significantly increased in such repeated contraction/relaxation. Altogether, it is suggested that the system is valuable for analyzing structural changes and physiological responses to several regulators in the field of penile medicine.

Human tissue kallikrein-1 protects against the development of erectile dysfunction in a rat model of hyperhomocysteinemia

The aim of this study was to investigate the mechanism by which a diet inducing high hyperhomocysteinemia (HHcy) leads to the deterioration of erectile function in rats and whether this is inhibited by expression of the human tissue kallikrein-1 (hKLK1) gene. We established a rat model of HHcy by feeding methionine (Met)-rich diets to male Sprague-Dawley (SD) rats. Male wild-type SD rats (WTRs) and transgenic rats harboring the hKLK1 gene (TGRs) were fed a normal diet until 10 weeks of age. Then, 30 WTRs were randomly divided into three groups as follows: the control (n = 10) group, the low-dose (4% Met, n = 10) group, and the high-dose (7% Met, n = 10) group. Another 10 age-matched TGRs were fed the high-dose diet and designated as the TGR+7% Met group. After 30 days, in all four groups, erectile function was measured and penile tissues were harvested to determine oxidative stress, endothelial cell content, and penis fibrosis. Compared with the 7% Met group, the TGR+7% Met group showed diminished HHcy-induced erectile dysfunction (ED), indicating the improvement caused by hKLK1. Regarding corpus cavernosum endothelial cells, hKLK1 preserved endothelial cell-cell junctions and endothelial cell content, and activated protein kinase B/endothelial nitric oxide synthase (Akt/eNOS) signaling. Fibrosis assessment indicated that hKLK1 preserved normal penis structure by inhibiting apoptosis in the corpus cavernosum smooth muscle cells. Taken together, these findings showed that oxidative stress, impaired corpus cavernosum endothelial cells, and severe penis fibrosis were involved in the induction of ED by HHcy in rats, whereas hKLK1 preserved erectile function by inhibiting these pathophysiological changes.

MicroRNA-205 is associated with diabetes mellitus-induced erectile dysfunction via down-regulating the androgen receptor

As a major class of regulatory genes in majority metazoans, microRNAs (miRs) play an important role in various diseases including diabetes mellitus (DM). Lack of androgens has previously been associated with DM-induced erectile dysfunction (DMED). In addition, the biological functioning of androgen is mediated by androgen receptor (AR). Herein, we sought to investigate whether miRs participate in AR-associated DMED. Sprague-Dawlay rats were employed to establish DMED models. After modelling, levels of miR-205 and AR in their cavernous bodies were measured. The relationship between miR-205 and AR was verified using a dual-luciferase reporter gene assay. The underlying regulatory mechanisms of miR-205 were investigated in concert with the treatment of mimics or inhibitors of miR-205, or AR overexpression in the cavernous smooth muscle cells (CSMCs) isolated from rats with DMED. Meanwhile, the effects of miR-205 and AR on cell proliferation and apoptosis were evaluated using MTT assay and flow cytometry respectively. Rats with DMED presented with increased miR-205 and decreased AR levels in the cavernous bodies. AR was identified as a target gene of miR-205. Down-regulation of miR-205 or up-regulation of AR could increase proliferation and inhibits apoptosis of CSMCs in addition to improvements in the erectile functioning of rats with DMED. In summary, miR-205 may contribute to the pathogenesis of DMED via down-regulation of AR expressions.