Ziziphus jujube ameliorated cavernosal oxidative stress and fibrotic processes in cavernous nerve injury-induced erectile dysfunction in a rat model

Caveolin-1 scaffolding domain-derived peptide enhances erectile function by regulating oxidative stress, mitochondrial dysfunction, and apoptosis of corpus cavernosum smooth muscle cells in rats with cavernous nerve injury

AIM

Increased corpus cavernosum smooth muscle cells (CCSMCs) apoptosis in the penis due to cavernous nerve injury (CNI) is a crucial contributor to erectile dysfunction (ED). Caveolin-1 scaffolding domain (CSD)-derived peptide has been found to exert potential antiapoptotic properties. However, whether CSD peptide can alleviate CCSMCs apoptosis and ED in CNI rats remains unknown. The study aimed to determine whether CSD peptide can improve bilateral CNI-induced ED (BCNI-ED) by enhancing the antiapoptotic processes of CCSMCs.

MAIN METHODS

Fifteen 10-week-old male Sprague-Dawley (SD) rats were randomly classified into three groups: sham surgery (Sham) group and BCNI groups that underwent saline or CSD peptide treatment respectively. At 3 weeks postoperatively, erectile function was assessed and the penis tissue was histologically examined. Furthermore, an in vitro model of CCSMCs apoptosis was established using transforming growth factor-beta 1 (TGF-β1) to investigate the mechanism of CSD peptide in treating BCNI-ED.

KEY FINDINGS

In BCNI rats, CSD peptide significantly prevented ED and decreased oxidative stress, the Bax/Bcl-2 ratio, and the levels of caspase3. TGF-β1-treated CCSMCs exhibited severe oxidative stress, mitochondrial dysfunction, and apoptosis. However, CSD peptide partially reversed these alterations.

SIGNIFICANCE

Exogenous CSD peptide could improve BCNI-ED by inhibiting oxidative stress, the Bax/Bcl-2 ratio, and caspase3 expression in penile tissue. The underlying mechanism might involve the regulatory effects of CSD peptide on oxidative stress, mitochondrial dysfunction, and apoptosis of CCSMCs following CNI. This study highlights CSD peptide as an effective therapy for post-radical prostatectomy ED (pRP-ED).

NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution

BACKGROUND

Previous studies have shown that oxidative stress contributes to hyperglycemia-induced erectile dysfunction. A preferential direct inhibitor of NOX1 and NOX4, GKT-137831, exhibited a strong anti‑oxidative role via blockade of reactive oxygen species (ROS) generation in endothelial cells, but whether GKT-137831 could improve erectile function was not clear.

AIM

Our study was designed to investigate the effect of NOX1/4 inhibition on improving diabetic erectile dysfunction (ED) in rats.

METHODS

We used streptozotocin to induce type 1 diabetes mellitus (DM) in 32 male Sprague Dawley (SD) rats (8 weeks old). Eight weeks later, type 1 diabetes mellitus-induced erectile dysfunction (DMED) in rats was confirmed using an apomorphine test. Our study consisted of 3 groups: (i) nondiabetic control group (n = 8), (ii) DMED + vehicle group (DMED group; n = 8), and (iii) DMED + GKT-137831 group (n = 9); GKT-137831 was given as a once-daily intraperitoneal injection for 4 weeks. Cavernous nerve electrostimulation was used to evaluate erectile function. Western blot, ELISA, immunohistochemistry, and immunofluorescence were used to measure expression of specific proteins, and DHE fluorescent probe was performed to detect ROS level.

OUTCOMES

Intracavernous pressure (ICP), nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway, oxidative stress level, inflammatory response, corporal autophagy, and apoptosis were measured.

RESULTS

Erectile function in the DMED group was significantly impaired compared to the nondiabetic control group, whereas this impairment was improved with GKT-137831 treatment by 70%. Similarly, endothelial function and overactivated oxidative stress in the corpus cavernosum (CC) of the DMED + GKT-137831 group were improved. The DMED group showed serious inflammatory responses and excessive autophagy, which were inhibited by GKT-137831 treatment in the DMED + GKT-137831 group.

CLINICAL TRANSLATION

Our study showed improvement in erectile function with GKT-137831 in a diabetic rat ED model.

STRENGTH AND LIMITATIONS

This study suggested for the first time that GKT-137831, an NOX1/4 inhibitor undergoing clinical trials, is effective in improving erectile function in rats with type 1 DMED. However, we only investigated GKT-137831 treatment of streptozotocin-induced type 1 diabetic rats, and therapeutic evidence in other types of diabetes is lacking.

CONCLUSION

GKT-137831 improves erectile function by 70% in type 1 DMED rats and constitutes a promising compound for the treatment of type 1 DMED, likely by inhibition of overactivated oxidative stress, down-regulation of proinflammatory factors, and amelioration of excessive autophagy and endothelial function. B Zhou, Y Chen, H Yuan, et al. NOX1/4 Inhibitor GKT-137831 Improves Erectile Function in Diabetic Rats by ROS Reduction and Endothelial Nitric Oxide Synthase Reconstitution. J Sex Med 2021;XX:XXX-XXX.

X-ray micro-computed tomography in the assessment of penile cavernous fibrosis in a rabbit castration model

BACKGROUND

Current assessment methods of penile cavernous fibrosis in animal models have limitations due to the inability to provide complex and volume analysis of fibrotic alterations.

OBJECTIVE

The aim was to evaluate micro-computed tomography (micro-CT) for assessment of cavernous fibrosis and compare it with histological, histochemical, immunohistochemical, and RT-PCR analysis.

MATERIALS AND METHODS

A controlled trial was performed involving 25 New Zealand male rabbits with induced testosterone deficiency by orchidectomy. Penile samples were obtained before and after 7, 14, 21, 84 days from orchidectomy. We consistently performed: a) gray value analysis of corpora cavernosa 3D models reconstructed after micro-CT; b) morphometry of smooth muscles/connective tissue ratio, collagen type I/III ratio, and area of TGF-beta-1 expression in corpora cavernosa; c) RT-PCR of TGF-beta-1 expression.

RESULTS

Micro-CT allowed visualization of penile structures at the resolution comparable to light microscopy. Gray values of corpora cavernosa decreased from 1673 (1512-1773) on the initial day to 1184 (1089-1232) on 21 day (p < 0,005); however, on 84 day, it increased to 1610 (1551-1768). At 21 and 84 days, there were observed a significant decrease in smooth muscle/connective tissue ratio and a significant increase in collagen type I/III ratio (p < 0,05). TGF-beta1 expression increased on 84 day according to immunohistochemistry (p < 0,005). RT-PCR was impossible to conduct due to the absence of RNA in obtained samples after micro-CT.

DISCUSSION AND CONCLUSIONS

Micro-CT provided 3D visualization of entire corpora cavernosa and assessment of radiodensity alterations by gray value analysis in fibrosis progression. We speculate that gray value changes at early and late fibrosis stages could be related to tissue reorganization. RT-PCR is impossible to conduct on tissue samples studied by micro-CT due to RNA destruction. We also suggest that micro-CT could negatively affect the immunohistochemical outcome, as a significant increase of TGF-beta-1 expression occurs later than histological fibrotic signs. This article is protected by copyright. All rights reserved.