Administration of H2S improves erectile dysfunction by inhibiting phenotypic modulation of corpus cavernosum smooth muscle in bilateral cavernous nerve injury rats

Abstract

Phenotypic modulation of Corpus Cavernosum Smooth Muscle Cells (CCSMCs) is an important step in the development and progression of bilateral cavernous nerve injury induced erectile dysfunction (BCNI-ED). To investigate the effect of exogenous hydrogen sulfide (H₂S) on the phenotypic modulation of CCSMCs in BCNI-ED rats, a total of 18 male Sprague-Dawley rats were equally divided into 3 groups, including sham-operated (Sham) group, BCNI group and BCNI treated with NaHS (BCNI + NaHS) group. The treated group received intraperitoneal injection of NaHS (100 μmol kg^-1day^-1) for 4 weeks starting day 1 postoperatively. Erectile function was measured by the ratio of intracavernous pressure (ICP)/mean arterial pressure (MAP), and relevant tissues were harvested for Immunohistochemistry, Hematoxylin and eosin (H&E), Masson's trichrome staining, H₂S fluorescent probe WSP-1 and Western blot. The primary CCSMCs were isolated and pretreatment with NaHS before exposed to PDGF-BB (platelet-derived growth factor). Relative expression mRNA and protein of phenotypic biomarkers, RhoA, ROCK-1 and cell cycle proteins were detected. Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST) and H₂S levels in penile tissue was significantly decreased in the BCNI group compared with the Sham group. Compared with the BCNI group, administration of NaHS significantly increased the ratio of ICP/MAP, ratio of smooth muscle to collagen, expressions of a-SMA, calponin and decreased the expression of OPN, collagen-I, RhoA, ROCK1 in the penile tissue. PDGF-BB-treated CCSMCs exhibited higher expression of OPN, RhoA, ROCK1, and lower α-SMA, calponin, which were attenuated by NaHS pretreatment. NaHS suppressed RhoA/ROCK activity and decreased the expression of CDK2, Cyclin E₁, while increased the expression of P27^kip1 induced by PDGF-BB in CCSMCs. Taken together, this study indicated that exogenous H₂S inhibited the phenotypic modulation of CCSMCs by suppressing RhoA/ROCK1 signaling and affecting its downstream factor, CDK2, Cyclin E_1, P27^kip1, thereby improved BCNI rat erectile function.

Keywords: Bilateral cavernous nerve injury; Erectile dysfunction; Hydrogen sulfide; Phenotype modulation; Radical prostatectomy; RhoA/ROCK.