Serkan Karakus

Beneficial Effect of the Nitric Oxide Donor Compound 3-(1,3-Dioxoisoindolin-2-yl)Benzyl Nitrate on Dysregulated Phosphodiesterase 5, NADPH Oxidase, and Nitrosative Stress in the Sickle Cell Mouse Penis: Implication for Priapism Treatment.

Patients with sickle cell disease (SCD) display priapism, and dysregulated nitric oxide (NO) pathway may contribute to this condition. However, current therapies offered for the prevention of priapism in SCD are few. The 3-(1,3-dioxoisoindolin-2-yl)benzyl nitrate (compound 4C) was synthesized through molecular hybridization of hydroxyurea and thalidomide, which displays an NO-donor property. This study aimed to evaluate the effects of compound 4C on functional and molecular alterations of erectile function in murine models that display low NO bioavailability, SCD transgenic mice, and endothelial NO synthase and neuronal NO synthase double gene-deficient (dNOS−/) mice, focusing on the dysregulated NO–cGMP– phosphodiesterase type 5 (PDE5) pathway and oxidative stress in erectile tissue. Wild-type, SCD, and dNOS−/− mice were treated with compound 4C (100 μmol/kg/d, 3 weeks). Intracavernosal pressure in anesthetized mice was evaluated. Corpus cavernosum tissue was dissected free and mounted in organ baths. SCD and dNOS−/− mice displayed a priapism phenotype, which was reversed by compound 4C treatment. Increased corpus cavernosum relaxant responses to acetylcholine and electrical-field stimulation were reduced by 4C in SCD mice. Likewise, increased sodium nitroprusside–induced relaxant responses were reduced by 4C in cavernosal tissue from SCD and dNOS−/− mice. Compound 4C reversed PDE5 protein expression and reduced protein expressions of reactive oxygen species markers, NADPH oxidase subunit gp91phox, and 3-nitrotyrosine in penises from SCD and dNOS−/− mice. In conclusion, 3-week therapy with the NO donor 4C reversed the priapism in murine models that display lower NO bioavailability. NO donor compounds may constitute an additional strategy to prevent priapism in SCD.

Testosterone replacement in transgenic sickle cell mice controls priapic activity and upregulates PDE5 expression and eNOS activity in the penis

Sickle cell disease (SCD)‐associated priapism is characterized by decreased nitric oxide (NO) signaling and downregulated phosphodiesterase (PDE)5 protein expression and activity in the penis. Priapism is also associated with testosterone deficiency, but molecular mechanisms underlying testosterone effects in the penis in SCD are not known. Given the critical role of androgens in erection physiology and NO synthase (NOS)/PDE5 expression, we hypothesized that testosterone replacement to eugonadal testosterone levels reduces priapism by reversing impaired endothelial (e)NOS activity and molecular abnormalities involving PDE5. Adult male transgenic Berkeley sickle cell (Sickle) and wild‐type (WT) mice were implanted with testosterone pellets, which release 1.2 μg testosterone/day for 21 days, or vehicle. After 21 days, animals underwent erectile function assessment followed by collection of blood for serum testosterone measurements, penes for molecular analysis, and seminal vesicles as testosterone‐responsive tissue. Serum testosterone levels were measured by radioimmunoassay; protein expressions of PDE5, α‐smooth muscle actin, eNOS and nNOS, and phosphorylation of PDE5 at Ser‐92, eNOS at Ser‐1177, neuronal (n) NOS at Ser‐1412, and Akt at Ser‐473 were measured by Western blot in penile tissue. Testosterone treatment reversed downregulated serum testosterone levels and increased (p < 0.05) the weight of seminal vesicles in Sickle mice to levels comparable to that of WT mice, indicating restored testosterone levels in Sickle mice. Testosterone treatment reduced (p < 0.05) prolonged detumescence in Sickle mice and normalized downregulated P‐PDE5 (Ser‐92), PDE5, P‐eNOS (Ser‐1177), and P‐Akt (Ser‐473) protein expressions in the Sickle mouse penis. Testosterone treatment did not affect P‐nNOS (Ser‐1412), eNOS, nNOS, or α‐smooth muscle actin protein expressions in the Sickle mouse penis. In conclusion, in the mouse model of human SCD, increasing testosterone to eugonadal levels reduced priapic activity and reversed impaired Akt/eNOS activity and PDE5 protein expression in the penis.

S-nitrosylation of NOS pathway mediators in the penis contributes to cavernous nerve injury-induced erectile dysfunction

AbstractcGMP-independent nitric oxide (NO) signaling occurs via S-nitrosylation. We evaluated whether aberrant S-nitrosylation operates in the penis under conditions of cavernous nerve injury and targets proteins involved in regulating erectile function. Adult male Sprague–Dawley rats underwent bilateral cavernous nerve crush injury (BCNI) or sham surgery. Rats were given a denitrosylation agent N-acetylcysteine (NAC, 300 mg/kg/day) or vehicle in drinking water starting 2 days before BCNI and continuing for 2 weeks following surgery. After assessment of erectile function (intracavernous pressure), penes were collected for measurements of S-nitrosylation by Saville–Griess and TMT-switch assays and PKG-I function by immunoblotting of phospho (P)-VASP-Ser-239. Erectile function was decreased (P < 0.05) after BCNI, and it was preserved (P < 0.05) by NAC treatment. Total S-nitrosothiols and total S-nitrosylated proteins were increased (P < 0.05) after BCNI, and these were partially prevented by NAC treatment. S-nitrosylation of sGC was increased (P < 0.05) after BCNI, and it was prevented (P < 0.05) by NAC treatment. S-nitrosylation of eNOS was increased (P < 0.05) after BCNI, and showed a trend towards decrease by NAC treatment. Protein expression of P-VASP-Ser-239 was decreased (P < 0.05) after BCNI, and showed a trend towards increase by NAC treatment. In conclusion, erectile dysfunction following BCNI is mediated in part by S-nitrosylation of eNOS and its downstream signaling mediator GC, while denitrosylation protects erectile function by preserving the NO/cGMP signaling pathway.

cAMP-dependent post-translational modification of neuronal nitric oxide synthase neuroprotects penile erection in rats

To evaluate neuronal nitric oxide (NO) synthase (nNOS) phosphorylation, nNOS uncoupling, and oxidative stress in the penis and major pelvic ganglia (MPG), before and after the administration of the cAMP‐dependent protein kinase A (PKA) agonist colforsin in a rat model of bilateral cavernous nerve injury (BCNI),which mimics nerve injury after prostatectomy.

PD19-06 NO-RELEASING NANOPARTICLES DECREASE DETRUSOR OVERACTIVITY IN DNOS-/- KNOCKOUT AND TRANSGENIC SICKLE CELL MICE

INTRODUCTION AND OBJECTIVE:Nitric oxide (NO) signaling pathway plays an important role in the urethral and penile smooth muscle tone. Additionally, NO may contribute to the regulation of bladder sm...

Phosphodiesterase type 5 in men with vasculogenic and post-radical prostatectomy erectile dysfunction: Is there a molecular difference?

To clarify the molecular basis of penile erection at the human level and distinguish the mechanisms underlying vasculogenic and post‐radical prostatectomy (RP) erectile dysfunction (ED) subtypes.

MP45-01 POST-TRANSLATIONAL MODIFICATION OF NEURONAL NITRIC OXIDE SYNTHASE IN THE HUMAN ERECTILE TISSUE FOLLOWING RADICAL PROSTATECTOMY

InterStim implantation. Brain activity during urgency was compared to no urgency, and analysis was stratified according to response to InterStim . RESULTS: The study included 12 women with idiopathic OAB with normal emptying (median age 63.5, IQR 11 years). All women underwent pre-InterStim fMRI, and 7 completed stage 2 InterStim and underwent post-InterStim fMRI (i.e. 7 responders, 5 non-responders). Among responders, brain activity decreased in the left cingulate gyrus (x,y,z coordinates: -5, 23, 39, p1⁄40.048) and left frontal gyrus (-5, 23, 39, p1⁄40.04) after InterStim implantation (figure 1). There were no areas of increased brain activity after InterStim implantation. Women who responded to InterStim had increased brain activity on their pre-InterStim fMRI in multiple cortical regions, including the cingulate cortex, inferior frontal gyrus, insula, and thalamus. There were no differences in ICIQ-FLUTS filling scores or pre-InterStim fMRI filling volumes between responders and non-responders (p>0.05). CONCLUSIONS: SNS with InterStim appears to attenuate increased brain activity in women with OAB. Women with OAB and increased brain activity during bladder filling may experience greater treatment response. fMRI has preliminarily detected a phenotype of OAB that may predict therapeutic response to InterStim .