Low androgen status inhibits erectile function by inducing eNOS uncoupling in rat corpus cavernosum

Nicotine is associated with smoking dependence and vascular inflammation through cotinine: A mediation analysis

INTRODUCTION

The main alkaloid component in cigarettes is nicotine. Cotinine, a metabolite of nicotine, is capable of causing dependence effects through endless mechanisms modulated by the ion channel nicotinic acetylcholine receptors nAChRs. Nicotine and cotinine can also cause damage to blood vessels through a chronic inflammatory process mediated by the Ligand-Tie2 Angiopoietin Receptor system. Hypoxic conditions that occur due to vascular inflammation cause a decrease in the concentration of nitric oxide (NO). This study aimed to evaluate the relationship between NO levels and cotinine through the expression of nAChRs that mediate the nicotine dependence mechanism and Tie2 (Tyrosine Kinase 2) expression.

METHODS

A cross-sectional study was conducted with 200 participants grouped into two groups based on their smoking status: 100 smokers and 100 non-smokers. All participants were men aged 20-40 years with no history of cardiovascular disease, diabetes mellitus, or dyslipidemia, and were not currently on medication. According to the parameters used, all blood samples were taken from peripheral blood for analysis using the ELISA kit or Colorimetric Assay Kit.

RESULTS

Cigarette consumption increases blood cotinine concentrations in smokers and causes dependence by modulating nAChRs. The study indicates an emerging cycle regarding nicotine-cotinine consumption and nAChRs expression. In addition, the data in this study showed a significant relationship (p<0.001) regarding the cycle formed with decreased NO levels as a result of damage caused by Tie2-mediated inflammation.

CONCLUSIONS

There is a relationship between NO levels and cotinine through nAChRs, which mediate the nicotine dependence mechanism and Tie2 expression.

Effect of hypoandrogenism on expression of transient receptor potential vanilloid channels in rat penile corpus cavernosum and erectile function

BACKGROUND

Hypoandrogenism is a cause of erectile dysfunction (ED). Vascular smooth muscle cell contraction and relaxation are regulated by TRPV1-4 channels. However, the influence of hypoandrogenism on TRPV1-4 and its relationship with erectile function remain unclear.

AIM

To reveal whether hypoandrogenism affects erectile function by influencing TRPV1-4 expression in the corpus cavernosum of rats.

METHODS

Male Sprague-Dawley rats (N = 36) aged 8 weeks were assigned to 6 groups at random (n = 6): sham operation, castrated, castrated + testosterone replacement, sham operation + transfection, castrated + transfection, and castrated + empty transfection. Four weeks after castration, 20 μL of lentiviral vector (1 × 108 TU/mL) carrying the TRPV4 gene was injected into the penile cavernous tissue of the transfection groups. One week after transfection, the maximum intracavernous pressure (ICPmax)/mean arterial pressure (MAP) and the content of TRPV1-4, phosphorylated eNOS (p-eNOS)/eNOS, and nitric oxide (NO) in penile cavernous tissue of each group were measured.

OUTCOMES

Under low androgen conditions, TRPV4 expression in endothelial cells in the rat penile cavernosum was sharply reduced, resulting in a decrease in p-eNOS/eNOS and NO content, which could inhibit erectile function.

RESULTS

In rat penile cavernous tissue, TRPV1-4 was expressed in the cell membranes of endothelial cells and smooth muscle cells. The ICPmax/MAP and the content of TRPV4, p-eNOS/eNOS, and NO end product nitrite level in rat penile cavernous tissue was markedly reduced in the castrated group as compared with the sham group (P < .05). The ICPmax/MAP and the content of TRPV4, p-eNOS/eNOS, and NO end product nitrite level in rat penile cavernous tissue were markedly improved in the castrated + transfection group vs the castrated group (P < .01).

CLINICAL IMPLICATIONS

Upregulation of TRPV4 expression in penile cavernosum tissue might be a viable therapeutic for ED caused by hypoandrogenism.

STRENGTHS AND LIMITATIONS

The specific mechanism of TRPV4 in ED needs to be further verified by androgen receptor or TRPV4 gene knockout experiments.

CONCLUSION

Hypoandrogenism may cause ED by reducing the expression of TRPV4 in rat penile cavernous tissue. Upregulation of TRPV4 expression in penile cavernous tissue can increase the ratio of p-eNOS/eNOS and NO levels and ameliorate the erectile function of castrated rats.

Understanding human aging and the fundamental cell signaling link in age-related diseases: the middle-aging hypovascularity hypoxia hypothesis

Aging-related hypoxia, oxidative stress, and inflammation pathophysiology are closely associated with human age-related carcinogenesis and chronic diseases. However, the connection between hypoxia and hormonal cell signaling pathways is unclear, but such human age-related comorbid diseases do coincide with the middle-aging period of declining sex hormonal signaling. This scoping review evaluates the relevant interdisciplinary evidence to assess the systems biology of function, regulation, and homeostasis in order to discern and decipher the etiology of the connection between hypoxia and hormonal signaling in human age-related comorbid diseases. The hypothesis charts the accumulating evidence to support the development of a hypoxic milieu and oxidative stress-inflammation pathophysiology in middle-aged individuals, as well as the induction of amyloidosis, autophagy, and epithelial-to-mesenchymal transition in aging-related degeneration. Taken together, this new approach and strategy can provide the clarity of concepts and patterns to determine the causes of declining vascularity hemodynamics (blood flow) and physiological oxygenation perfusion (oxygen bioavailability) in relation to oxygen homeostasis and vascularity that cause hypoxia (hypovascularity hypoxia). The middle-aging hypovascularity hypoxia hypothesis could provide the mechanistic interface connecting the endocrine, nitric oxide, and oxygen homeostasis signaling that is closely linked to the progressive conditions of degenerative hypertrophy, atrophy, fibrosis, and neoplasm. An in-depth understanding of these intrinsic biological processes of the developing middle-aged hypoxia could provide potential new strategies for time-dependent therapies in maintaining healthspan for healthy lifestyle aging, medical cost savings, and health system sustainability.

Downregulation of the expression of galanin impairs erectile function in hypoandrogenic rats

Background

The relationship between galanin and erectile function under low androgen levels is still unclear.

Aim

To explore whether a low testosterone level damages the erection of a rat by regulating the expression of galanin and GalR in penile cavernous tissue.

Methods

Thirty-six male Sprague-Dawley rats, 8 weeks of age, were randomly grouped as follows (n = 6): control, castration, castration + testosterone replacement, control + transfection, castration + transfection, and castration + empty transfection. At 4 weeks after castration, rats in the transfection group were injected with lentivirus carrying the targeting galanin gene (2 × 10⁸ TU/mL, 10 μL) in the corpus cavernosum. After 1 week of injection, the intracavernosal pressure (ICP), mean arterial blood pressure (MAP), nitric oxide (NO), serum testosterone concentration, galanin, GalR1-3, ROCK1, ROCK2, and p-eNOS/eNOS in the rat penile tissues were evaluated.

Outcomes

ICPmax/MAP and the expression of galanin in the corpus cavernosum in castrated rats were obviously decreased as compared with those in the control rats.

Results

The castrated rats showed remarkably lower ICPmax/MAP, galanin, GalR1-3, p-eNOS/eNOS, and NO content and markedly higher ROCK1 and ROCK2 in penile tissues than the control group (P < .05). The transfected rats administrated with LV Gal had obviously higher ICPmax/MAP, p-eNOS/eNOS, and NO content and less ROCK1 and ROCK2 protein expression in the corpus cavernosum when compared with the castration group (P < .05).

Clinical Translation

Upregulating the expression of galanin in the penile corpus cavernosum might be a novel method of treating erectile dysfunction caused by a low androgen level.

Strengths and Limitations

The conclusions obtained in the animal experiments need to be confirmed in human data.

Conclusion

The erectile function of hypoandrogen rats might be inhibited by downregulating the level of galanin and GalR1-3, upregulating ROCK1 and ROCK2 levels, and inhibiting the eNOS/NO signaling pathway in penile corpus cavernosum.

Low testosterone state inhibits erectile function by downregulating the expression of GIT1 in rat penile corpus cavernosum

Background

The mechanism of erectile dysfunction (ED) caused by a low androgen level is still not clear.

Aim

To explore the influence of the low testosterone state on G protein-coupled receptor kinase interactor 1 (GIT1) and its contact to erectile function.

Methods

Thirty male Sprague-Dawley rats aged 8 weeks were distributed at random into 5 groups: control (sham operated), castration, testosterone supplement after castration, castration + vacant lentiviral transfection, and castration + lentiviral transfection. The testis and epididymis were removed through a scrotal incision to develop castrated rats. Four weeks after castration, a lentivirus carrying the GIT1 gene was injected into the middle of rat penile corpus cavernosum. One week after transfection, maximum intracavernous pressure/mean arterial pressure (ICPmax/MAP), serum testosterone, nitric oxide, GIT1, endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS), p-eNOS/eNOS, and the interaction between eNOS and GIT1 were assessed in the rats.

Outcomes

The levels of GIT1 in the penile cavernous tissue of castrated rats are significantly lower than that of controls.

Results

GIT1 was expressed in the cytoplasm and cell membrane of vascular endothelial cells and smooth muscle cells in rat penile tissue. In comparison with normal rats, the castrated rats showed lower levels of GIT1 expression, GIT1 and eNOS interaction, p-eNOS/eNOS, nitric oxide, and ICPmax/MAP (P < .01). Overexpression of GIT1 can intensively enhance the expression level of GIT1, the interaction between GIT1 and eNOS, p-eNOS/eNOS, nitric oxide, and ICPmax/MAP in rats (P < .01).

Clinical Translation

Modulating the interaction between eNOS and GIT1 might be a novel method of treating ED caused by a low androgen level.

Strengths and Limitations

The impact of GIT1 phosphorylation on the activity of eNOS and its possible mechanisms affecting erectile function require further study.

Conclusion

A low testosterone state inhibits erectile function in rats by reducing the expression of GIT1 and the protein interaction between GIT1 and eNOS.

Effect of low androgen levels on transient receptor potential channels expression in rat penile corpus cavernosum tissue and its relationship with erectile function

The exact mechanism by which testosterone deficiency causes ED has not yet been elucidated. TRPC is involved in the process of smooth muscle cell contraction and relaxation. The effect of androgens on TRPCs and their relationship with erectile function are currently unclear. Thirty male SD rats were randomly divided into six groups: control group, castration group, castration + testosterone (T) group (cast + T), control + transfection group (control + trans), control + empty transfection group and castration + transfection group (cast + trans). The transfection group rats were given with lentivirus (1 × 10⁸ TU/mL, 15 μl) carrying the siRNA targeting TRPC4 gene in the rat penile cavernous tissue at 4 weeks after castration. The tests were performed at 5 weeks after castration. Comparing the cast group with the control, the ICPmax/MAP, p-eNOS/eNOS and NO levels in the rat penile tissue were significantly lower (p < 0.01) and the level of TRPC3, TRPC4 and TRPC6 in the rat penile tissue was significantly increased (p < 0.01). When the cast + trans group was compared to the cast group, ICPmax/MAP was markedly higher (p < 0.05), and the level of the TRPC4 was remarkably lower (p < 0.05). Low androgen levels might inhibit an erectile function through up-regulation of the expression of TRPC3, TRPC4 and TRPC6 in rat penile cavernous tissue. Inhibition the level of TRPC4 in rat penile tissue may improve the erectile function in low androgen levels.

Low androgen status inhibits erectile function by up-regulating the expression of proteins of mitochondria-associated membranes in rat corpus cavernosum

OBJECTIVE

To investigate the effect of low androgen status on mitochondria-associated membranes (MAMs) and its relationship with erectile function.

METHODS

A total of 36 eight-week-old male Sprague-Dawley rats were randomly divided into 6 groups: the control (sham-operated) group, the castration group, the castration + testosterone (cast + T) group, the control + siRNA group, the cast + siRNA group, and the cast + empty vector group. Testosterone propionate (3 mg/kg) was subcutaneously injected into the rats in the cast + T group every other day starting from the second day after the surgery. Four weeks later, lentiviral vectors carrying phosphofurin acidic cluster sorting protein 2 (PACS-2) gene-specific siRNA (1 × 10⁸ TU/ mL, 10 μL) were injected into the rats in the siRNA groups. At the 6th week of castration, the ratio of the maximum intracavernous pressure/the mean arterial pressure (ICPmax/MAP), the levels of nitric oxide (NO), endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS), fatty acid-CoA ligase 4 (FACL-4), PACS-2, and inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) in the penile corpus cavernosum were determined.

RESULTS

The FACL-4, PACS-2 and IP3R1 were primarily localized in the cytoplasm of endothelial cells and part of smooth muscle cells in the corpus cavernosum. The level of NO, the ratio of ICPmax/MAP, and p-eNOS/eNOS were decreased significantly in the castration group compared with the control group (P<0.01). The expressions of FACL-4, PACS-2, and IP3R1 were increased significantly in the castration group compared with the control group (P<0.01). The level of NO, the ratios of ICPmax/MAP, and the ratio of p-eNOS/eNOS were increased significantly in the cast + siRNA group compared with the castration group (P<0.01). The expressions of FACL-4 and PACS-2 were decreased significantly in the cast + siRNA group compared with the castration group (P<0.01).

CONCLUSION

Low androgen status up-regulated the expressions of patients in MAMs (FACL-4, PACS-2 and IP3R1) in the corpus cavernosum and inhibited the eNOS/NO/cGMP signaling pathway, resulting in impaired erectile function in rats. Erectile function may be improved by inhibiting the high expression of PACS-2 in the corpus cavernosum under low androgen state. This article is protected by copyright. All rights reserved.

The Etiology and Pathophysiology Genesis of Benign Prostatic Hyperplasia and Prostate Cancer: A New Perspective

Background: The etiology of benign prostatic hyperplasia and prostate cancer are unknown, with ageing being the greatness risk factor. Methods: This new perspective evaluates the available interdisciplinary evidence regarding prostate ageing in terms of the cell biology of regulation and homeostasis, which could explain the timeline of evolutionary cancer biology as degenerative, inflammatory and neoplasm progressions in these multifactorial and heterogeneous prostatic diseases. Results: This prostate ageing degeneration hypothesis encompasses the testosterone-vascular-inflamm-ageing triad, along with the cell biology regulation of amyloidosis and autophagy within an evolutionary tumorigenesis microenvironment. Conclusions: An understanding of these biological processes of prostate ageing can provide potential strategies for early prevention and could contribute to maintaining quality of life for the ageing individual along with substantial medical cost savings.

Low androgen status inhibits erectile function by increasing pyroptosis in rat corpus cavernosum

BACKGROUND

The mechanism of erectile dysfunction (ED) caused by low androgen status is not fully understood.

OBJECTIVES

To investigate whether low androgen status inhibits erectile function of rats by inducing pyroptosis in the corpus cavernosum (CC).

MATERIALS AND METHODS

Thirty-six eight-weeks-old healthy male Sprague-Dawley rats were equally divided into six groups: sham-operated group (4w sham, 8w sham), castration group (4w cast, 8w cast), and castration + testosterone (T) group (4w cast + T, 8w cast + T). The rats in castration + T groups were injected with testosterone propionate subcutaneously every other day. After 4 and 8 weeks, the ratio of maximum intracavernous pressure (ICPmax)/mean arterial pressure (MAP), the level of serum T, the concentration of nitric oxide (NO) and interleukin-1β (IL-1β), the expression of NOD-like receptor pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), Caspase-1 p20, gasdermin D-N (GSDMD-N), transforming growth factor β1 (TGF-β1), collagen-I, and collagen-III, the ratio of smooth muscle/collagen (SM/C), and the proportion of pyroptotic cells in the CC were analyzed.

RESULTS

The ratio of ICPmax/MAP (3/5 V) and SM/C, the level of NO and serum T was significantly decreased in castration groups when compared to other groups (p < 0.01). NLRP3, ASC, Caspase-1, and GSDMD were mainly expressed in the cytoplasm of smooth muscle cells (SMCs) and endothelial cells (ECs) in the CC. The expression of NLRP3, ASC, Caspase-1p20, GSDMD-N, IL-1β, TGF-β1, collagen-I, and collagen-III was significantly increased in castration groups when compared with other groups (p < 0.01). The proportion of pyroptotic cells in the CC was increased significantly in castration groups when compared with other groups (p < 0.05).

DISCUSSION AND CONCLUSION

Low androgen status inhibits erectile function of rats by promoting CC fibrosis and reducing NO synthesis through pyroptosis of SMCs and ECs in the CC.