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

Mode of cell death in the penile cavernous tissue of type 1 diabetes mellitus rats

BACKGROUND

Diabetes mellitus commonly causes endothelial cell and smooth muscle cell death in penile cavernous tissue.

AIM

The study sought to study the mode of cell death in the penile cavernous tissue in type 1 diabetic rats.

METHODS

A total of 36 Sprague Dawley rats 10 weeks of age were randomly divided into 2 groups: a normoglycemic group and type 1 diabetic group (intraperitoneal injection of Streptozotocin (STZ), 60 mg/kg). We randomly selected 6 rats from each group for tests at the end of 11, 14, and 18 weeks of age, respectively. All rats were able to eat and drink freely. The ratio of maximum intracavernous pressure to mean arterial pressure, concentration of serum testosterone, level of nitric oxide in the penile cavernosum, and expression of active caspase-1 (pyroptosis) and active caspase-3 (apoptosis) were determined.

OUTCOMES

At the end of weeks 4 and 8 of type 1 diabetes, the proportions of endothelial cells and smooth muscle cells undergoing apoptosis and pyroptosis in penile cavernous tissue are different.

RESULTS

The ratio of maximum intracavernous pressure to mean arterial pressure and nitric oxide levels were significantly lower in the 4- and 8-week diabetic groups than in the normoglycemic group (P < .01). Penile endothelial cell pyroptosis (5.67 ± 0.81%), smooth muscle cell apoptosis (23.72 ± 0.48%), total cell pyroptosis (9.67 ± 0.73%), and total apoptosis (10.52 ± 1.45%) were significantly greater in the 4-week diabetic group than in the normoglycemic group (P < .01). The proportion of endothelial cell pyroptosis (24.4 ± 3.69%), endothelial cell apoptosis (22.13 ± 2.43%), total cell pyroptosis (14.75 ± 0.93%), and total apoptosis (14.82 ± 1.08%) in the penile tissues of the 8-week diabetic group were significantly greater than those in the normoglycemic group (P < .01).The 8-week survival proportions of diabetic endothelial cells (38.86 ± 8.85%) and smooth muscle cells (44.46 ± 2.94%) was significantly lower than the 4-week survival proportions of endothelial cells (93.17 ± 8.07%) and smooth muscle cells (75.12 ± 4.76%) (P < .05).

CLINICAL TRANSLATION

Inhibition of cell death by different methods at different stages may be the key to the treatment of type 1 diabetes-induced erectile dysfunction.

STRENGTHS AND LIMITATIONS

The effect of type 1 diabetes on other types of cell death in penile cavernous tissue needs further study.

CONCLUSION

The mode of death of endothelial cells in the cavernous tissue of the penis in the early stage in diabetic rats is dominated by pyroptosis, and the death of smooth muscle cells is dominated by apoptosis. Endothelial cell and smooth muscle cell death are not consistent at different stages of diabetes progression.

A low testosterone level impairs erectile function by increasing endocan expression in rat penile corpus cavernosum

BACKGROUND

The mechanism by which a state of low testosterone leads to erectile dysfunction (ED) has not been determined. Endocan is a novel marker of endothelial function. However, whether endocan is involved in the regulation of erectile function under low testosterone levels remains unclear.

AIM

In this study we sought to determine whether a low-testosterone state inhibits erectile function by regulating endocan expression in the endothelial cells of the rat penile corpus cavernosum.

METHODS

Thirty-six male Sprague-Dawley rats aged 8 weeks were randomly assigned to 6 groups (n = 6 per group) as follows: (1) control, (2) castration, (3) castration + testosterone treatment (treated with 3 mg/kg testosterone propionate per 2 days), (4) control + transfection (4 weeks after castration, injected with lentiviral vector (1 × 108 transduction units/mL, 10 μL), (5) castration + transfection, or (6) castration + empty transfection. One week after the injection, we measured the maximal intracavernous pressure/mean arterial pressure (ICPmax/MAP), serum testosterone and nitric oxide (NO) levels, and the expression of endocan, phospho-endothelial NO synthase (p-eNOS), eNOS, phospho-protein kinase B (p-AKT), and AKT in the rat penile corpus cavernosum.

OUTCOMES

Under a low-androgen state, the expression of endocan in the rat penile corpus cavernosum was significantly increased, which inhibited the AKT/eNOS/NO signaling pathway and resulted in ED.

RESULTS

In the castration group, the expression of endocan in the rat penile corpus cavernosum was significantly higher than that in the control group (P < .05). Additionally, the levels of p-AKT/AKT, p-eNOS/eNOS, and NO in the rat penile corpus cavernosum and ICPmax/MAP were significantly lower in the castration group than in the control group (P < .05). In the castration + transfection group compared with the castration group there was a significant decrease in the expression of endocan (P < .05) and an increase in the ratios of p-AKT/AKT, p-eNOS/eNOS, and ICPmax/MAP (P < .05) in the rat penile corpus cavernosum.

CLINICAL IMPLICATIONS

Downregulating the expression of endocan in the penile corpus cavernosum may be a feasible approach for treating ED caused by hypoandrogenism.

STRENGTHS AND LIMITATIONS

The results of this study indicte that endocan may affect NO levels and erectile function through multiple signaling pathways, but further experiments are needed to clarify the relationship between endocan and androgens.

CONCLUSION

A low-testosterone state inhibits the AKT/eNOS/NO signaling pathway by increasing the expression of endocan in the rat penile corpus cavernosum and impairing erectile function in rats. Decreasing the expression of endocan in the penile corpus cavernosum can improve erectile function in rats with low testosterone levels.

Androgens and erectile dysfunction: from androgen deficiency to treatment

INTRODUCTION

Androgens play important roles in regulating the growth and development of the male reproductive system and maintaining libido and erectile function. The specific mechanisms by which androgen deficiency leads to erectile dysfunction (ED) are not yet fully understood.

OBJECTIVES

To understand the mechanisms and treatment of androgen deficiency-related ED.

METHODS

A literature search in the past 10 years was conducted in PubMed and Google Scholar to determine the effects of androgen deficiency on erectile function and the treatment of androgen deficiency.

RESULTS

Androgen deficiency can be caused by hypothalamic-pituitary lesions and injuries, testicular-related diseases and injuries, endocrine and metabolic disorders, the side effects of medication, and age. Androgen deficiency can lead to ED by inhibiting the NOS/NO/cGMP pathway (nitric oxide synthase/nitric oxide/cyclic guanosine monophosphate) and altering the expression of ion channel proteins, as well as by inducing oxidative stress, death, and fibrosis in penile corpus cavernosum cells. Testosterone replacement therapy is effective at improving the serum testosterone levels and erectile function in patients with androgen deficiency. For patients who need to maintain a low androgenic state, erectile function can be improved by lifestyle changes, treatment with phosphodiesterase type 5 inhibitors, low-intensity extracorporeal shock wave therapy, and stem cell therapy.

CONCLUSIONS

Androgen deficiency can affect the structure and function of the penile corpus cavernosum, leading to ED. Areas of further study include how androgen replacement therapy can improve erectile function and how to improve the maintenance of erectile function in patients with hypoandrogenic status.

A low androgenic state inhibits erectile function by suppressing endothelial glycosides in the penile cavernous tissue of rats

Background

The endothelial glycocalyx is an important barrier that protects the structure and function of endothelial cells. Androgen deficiency is a common factor that causes structural and functional impairment of endothelial cells.

Aim

To investigate changes in the endothelial glycocalyx in the penile corpus cavernosum of the rat with low androgen status and its relationship with erection function.

Methods

Eighteen 10-week-old Sprague-Dawley male rats were randomly divided into 3 groups (n = 6 each): sham operation, castration, and castration + testosterone replacement. The maximum intracavernosal pressure/mean arterial pressure of the penis was measured after modeling for 4 weeks. The expression levels of endothelial nitric oxide synthase (eNOS), phospho-eNOS, syndecan 1, heparanase, and nitric oxide in penile cavernous tissue and the serum levels of heparan sulfate, hyaluronic acid, tumor necrosis factor α, and interleukin 6 were determined. Transmission electron microscopy was used to observe the ultrastructure of the endothelial glycocalyx in penile tissue.

Outcomes

The thickness of the endothelial glycocalyx in the penile corpus cavernosum of castrated rats was significantly lower than that of the control group.

Results

In the castrated rats, the endothelial glycocalyx thickness, syndecan 1 level, ratio of phospho-eNOS to eNOS, nitric oxide level, and maximum intracavernosal pressure/mean arterial pressure (3 V, 5 V) were significantly lower than those in the sham group (P < .05). The expression of heparanase and the serum levels of tumor necrosis factor α and interleukin 6 were significantly higher in the castrated group than in the sham group (P < .05).

Clinical Translation

Upregulating the expression of the endothelial glycocalyx in the penile corpus cavernosum may be a new method for treating erectile dysfunction caused by low androgen levels.

Strengths and Limitations

This study confirms that low androgen status promotes the breakdown of the endothelial glycocalyx. However, further research is needed to determine whether androgens are related to the synthesis of the endothelial glycocalyx.

Conclusion

Low androgen status may suppress the level of nitric oxide in the cavernous tissue of the penis via impairment of the endothelial glycocalyx, resulting in inhibited erection function in rats.

Methylation of eNOS in the rat penile corpus cavernosum under different pathological states and its relationship with erectile function

BACKGROUND

It has been shown that methylation in the promoter region of eNOS can downregulate eNOS expression resulting in the endothelial dysfunction. However, it is unclear whether low androgen levels and type 1 diabetes cause ED by methylating the promoter region of eNOS in the penile corpus cavernosum.

OBJECTIVE

To clarify the effects of type 1 diabetes and hypo-androgen status on the methylation level of the promoter region of the eNOS gene in penile cavernous tissue and their relationship with the erectile function.

METHODS

Fifty-eight eight-week-old male Sprague-Dawley rats were randomly divided into six groups (n = 6): sham operation group, castration group, castration+testosterone (cast+T) group, normoglycemia group, diabetic group, and diabetic+methyltransferase inhibitor (5-aza-dc, 1.5 mg/kg) group. The ICPmax/MAP, serum T, the concentration of nitric oxide (NO), the expression of DNMT1, DNMT3a, DNMT3b, and eNOS, and the methylation level of the eNOS promoter region in penile corpus cavernosum of rat were examined 4 weeks after surgery in the sham-operated group, the castration group, and the castration + testosterone replacement group. Those tests were examined after 6 weeks using of methylation inhibitors in the normoglycemic group, the diabetic group, and the diabetic + methylation inhibitor group.

RESULTS

ICPmax/MAP, DNMT1, DNMT3a, DNMT3b, eNOS, and NO levels were significantly lower in castrated rats than in sham and cast+T rats (P < 0.05). ICPmax/MAP, eNOS, and NO levels were lower, and DNMT1, DNMT3a, and DNMT3b expression levels were significantly increased in the diabetic group compared with the normoglycemic and diabetic+methyltransferase inhibitor groups (P < 0.05). There was no significant difference in the methylation level of the promoter region of eNOS in penile cavernous tissue of castrated rats compared with the sham group or the testosterone replacement group. The methylation level of the promoter region of eNOS in penile cavernous tissue was significantly higher in the diabetic group than in the normoglycemic group and diabetic+methyltransferase inhibitor group (P < 0.05).

CONCLUSION

Although low androgen status inhibited the level of methyltransferase in rat penile cavernous tissue, did not affect the level of methylation in the promoter region of eNOS. Hyperglycemia inhibits the NO level in the penile cavernous tissue and the erectile function of rats by upregulating the methyltransferase level in the penile cavernous tissue and the methylation level in the promoter region of eNOS. Methylation inhibitors can partly improve the erectile function in type 1 diabetic rats.

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.

AKT/PACS2 Participates in Renal Vascular Hyperpermeability by Regulating Endothelial Fatty Acid Oxidation in Diabetic Mice

Diabetes is a chronic metabolic disorder that can cause many microvascular and macrovascular complications, including diabetic nephropathy. Endothelial cells exhibit phenotypic and metabolic diversity and are affected by metabolic disorders. Whether changes in endothelial cell metabolism affect vascular endothelial function in diabetic nephropathy remains unclear. In diabetic mice, increased renal microvascular permeability and fibrosis, as well as increased MAMs and PACS2 in renal endothelial cells, were observed. Mice lacking PACS2 improved vascular leakage and glomerulosclerosis under high fat diet. In vitro, PACS2 expression, VE-cadherin internalization, fibronectin production, and Smad-2 phosphorylation increased in HUVECs treated with high glucose and palmitic acid (HGHF). Pharmacological inhibition of AKT significantly reduced HGHF-induced upregulation of PACS2 and p-Smad2 expression. Blocking fatty acid β-oxidation (FAO) ameliorated the impaired barrier function mediated by HGHF. Further studies observed that HGHF induced decreased FAO, CPT1α expression, ATP production, and NADPH/NADP⁺ ratio in endothelial cells. However, these changes in fatty acid metabolism were rescued by silencing PACS2. In conclusion, PACS2 participates in renal vascular hyperpermeability and glomerulosclerosis by regulating the FAO of diabetic mice. Targeting PACS2 is potential new strategy for the treatment of diabetic nephropathy.

Icariin inhibits the formation of mitochondria-associated membranes (MAMs) and improves erectile function in rats treated with prostate radiation

BACKGROUND

Erectile function is usually impaired after radiation therapy in prostate cancer patients. eNOS is a key enzyme in the process of erection. Mitochondria-associated membranes (MAMs) are closely contacted with the production and bioactivity of eNOS.

OBJECTIVE

To study the mechanism of icariin improves the erectile function of rats treated with prostate radiation by controling the expression of MAMs in penile corpus cavernosum.

METHODS

Twenty 8-week-old healthy male SD rats were randomized to four groups: control group, radiation therapy (RT) group, icariin (10 mg/kg/d gavage) group, and RT + icariin (10 mg/kg/d gavage) group (n = 5). In RT group and RT + icariin group, rats were irradiated with X-rays to the prostate region (total dose 37.5 gray; 7.5 gray/day for 5 days). The ICPmax/MAP, NO concentration and the level of IP₃ R1, PACS2, FACL4, nNOS, p-eNOS, and eNOS in rats' penile cavernous tissue was determined 9 weeks after radiation therapy.

RESULTS

Compared with the control group and the RT + icariin group, the ICPmax/MAP of the RT group was remarkably reduced (P<0.05). The levels of p-eNOS/eNOS, nNOS and the concentration of NO in the penile cavernous tissue of the penis in the RT group were remarkably decreased compared to the control group and the RT + icariin group (P<0.05). The levels of IP₃ R1, PACS2, and FACL4 in penile cavernous tissue of the RT group were significantly higher than those in the control group and the RT + icariin group (P<0.05).

CONCLUSIONS

After prostate X-ray radiotherapy in rats, the formation of MAMs may be increased by increased expression of IP₃ R1, PACS2, and FACL4 in penile cavernous tissue, resulting in impaired erectile function. Icariin might increase p-eNOS/eNOS and improve erectile function in rats after prostate radiotherapy by inhibiting the expression of IP₃ R1, PACS2, and FACL4. This article is protected by copyright. All rights reserved.