Sildenafil inhibits the formation of superoxide and the expression of gp47 NAD[P]H oxidase induced by the thromboxane A2 mimetic, U46619, in corpus cavernosal smooth muscle cells

OBJECTIVE: To assess the effect of sildenafil on superoxide formation and p47(phox) (the active subunit of NADPH oxidase) expression in cultured corpus cavernosal smooth muscle cells (CVSMCs). MATERIALS AND METHODS: CVSMCs derived from rabbit penis were incubated with U46619 (thromboxane A2 analogue) with or without sildenafil for 1 or 16 h at 37 degrees C. Superoxide dismutase-inhibitable superoxide formation was assessed using the reduction of ferricytochrome c measured spectrophotometrically, and gp47(phox) assessed using Western blot analysis. The role of NAD[P]H oxidase and cGMP was further studied by using specific inhibitors of each. RESULTS: Superoxide formation was significantly greater in cells incubated with U46619 after 1 and 16 h incubation than in controls, an effect blocked by NADP(H) oxidase inhibitors. These effects of U46619 were inhibited by sildenafil (1 and 10 nmol/L), which in turn were negated by the guanylyl cyclase inhibitor, ODQ; 10 nmol/L sildenafil inhibited p47phox expression induced by U46619. CONCLUSIONS: Sildenafil is a potent inhibitor of superoxide formation in CVSMCs. This effect is mediated through the inhibition of PDE-5 which in turn augments the inhibitory action of the NO-cGMP axis on NAD[P]H oxidase expression and activity. This mechanism constitutes a new pharmacological action of sildenafil, consolidates the potential role of superoxide in ED, and indicates that thromboxane A(2) may be an important mediator of intrapenile oxidative stress.     

Effect of NADPH oxidases inhibition on the development of interstitial fibrosis in unilateral ureter obstruction rats

ObjectiveTo clarify whether the NADPH oxidases (NOXs) family contributed to the reactive oxygen species (ROS) production and subsequent interstitial fibrosis in unilateral ureter obstruction (UUO) rats. MethodsMale Wistar rats were randomly divided into sham operation group (n＝8), sham operation + apocynin treatment group (n＝8), UUO operation group (n＝8) and UUO operation+apocynin treatment group (n＝8). Either vehicle or apocynin (100 mg/kg per day) were given by gavage for 7 days after surgery. Rats were sacrificed at 7th day. ELISA was used to detect the activity of superoxide dismutase (SOD) and catalase (CAT), and the level of 8-iso-prostaglandin F2alpha (8-iso- PGF2α) in renal tissue. Western blotting was used to detect the protein expressions of NADPH oxidase subunit NOX2 and NOX4, α- smooth muscle actin(α-SMA), collagen I (COL-I) and the level of ERK1/ 2 phosphorylation (p-ERK1/2). ResultsUUO rats with vehicle displayed increased oxidative stress, as measured by renal tissue 8-iso-PGF2α, accompanied with increased renal expression of NADPH oxidases (NOX2, 1.5-fold and NOX4, 1.7-fold, respectively), compared with sham-operated rats (P＜ 0.05). Furthermore, vehicle treated UUO rats showed increased renal COL - I and α - SMA levels, compared with sham-operated rats (P＜0.05). ERK1/2 was also activated as detected by p-ERK1/2 expression in UUO rats with vehicle (P＜0.05). Apocynin treatment significantly decreased renal tissue 8-iso-PGF2α level and expressions of NOX2 (-28.7%) and NOX4 (-31.0%) in UUO rats, respectively, compared with vehicle treated rats (P＜0.05). And significant decrease of COL-I (-26.4%) and α-SMA expression (-80.0%) were also observed (P＜0.05). The activation of ERK1/2 in UUO rats was greatly inhibited by apocynin treatment (P＜0.01). Despite the pronounced dysregulation of pro – oxidative NOXs family, no compensatory increase of antioxidative enzyme activities occurred. ConclusionThe NOXs family contributes largely to the production of ROS and subsequent interstitial fibrosis after ureter ligation, and inhibition of the NOXs family may be a choice for preventing interstitial fibrosis.     

Phosphodiesterase 5 in the female pig and human urethra: morphological and functional aspects

OBJECTIVE: To characterize the distribution of phosphodiesterase 5 (PDE-5), cGMP and cGMP-dependent protein kinase I (PKG1), and to evaluate the effect of pharmacological inhibition of PDE-5 in isolated preparations of pig and human urethra, as the nitric oxide (NO)/cGMP pathway generates the main inhibitory signals to reduce resistance in the bladder outlet and urethra during emptying of the bladder. MATERIALS AND METHODS: After obtaining ethics committee approval, urethral specimens were obtained from three female patients during cystectomy, and from young female pigs. The specimens were prepared for immunohistochemical investigations and for functional studies in organ baths. Effects of sildenafil, vardenafil and tadalafil (1 nm to 30 microm) were studied in l-noradrenaline (1 microm)-activated or spontaneously contracted preparations, and on relaxations induced by electrical-field stimulation (EFS). Levels of cGMP were determined by radioimmunoassay. RESULTS: After stimulation with the NO donor, DETA NONO-ate (1 mm), there was greater cGMP-immunoreactivity (IR) in urethral and vascular smooth muscles. There was a wide distribution of cGMP- and vimentin-positive interstitial cells between pig urethral smooth muscle bundles. There was also cGMP-IR within NO-synthase-IR endothelium. There was PDE-5 IR within the urethral and vascular smooth muscle cells, but also in vascular endothelial cells that expressed cGMP-IR. In pig and human sections, there was strong PKG1-IR in alpha-actin-IR urethral smooth muscle cells that also contained IR for cGMP. Sildenafil, vardenafil and tadalafil caused mean (sem) concentration-dependent relaxations of the pig urethra which, at 30 microm, were 80 (3)% (11 samples), 81 (5)% (12 samples) and 64 (4)% (10 samples) of the spontaneous tone. The relaxation of L-noradrenaline-contracted female human urethra was 100% in response to 10 microm sildenafil, and 85 (15)% and 47 (13)% for 30 microm of vardenafil and tadalafil, respectively (three samples). Vardenafil or sildenafil (30 microm) doubled cGMP levels in pig specimens. There were no effects on cGMP levels with tadalafil. EFS (1-32 Hz) caused l-NG-nitroarginine-sensitive relaxations of pig urethral muscle that were increased in amplitude and duration by PDE-5 inhibition. At 0.1 microm, sildenafil, vardenafil or tadalafil significantly prolonged the mean (sem) duration of the relaxation at 4 Hz by 55 (19)%, 45 (14)% and 51 (12)%, respectively. CONCLUSIONS: PDE-5-, cGMP- and PKG1-IR is widely distributed in human and pig urethral tissues. Nerve-induced relaxations of urethral preparations were enhanced at low concentrations of sildenafil, vardenafil and tadalafil, whereas there were direct smooth muscle-relaxant actions of the PDE-5 inhibitors at high concentrations. Inhibition of PDE-5 might be an interesting option to facilitate cGMP-mediated relaxation of the outflow region.     

Pre-clinical evidence for the use of phosphodiesterase-5 inhibitors for treating benign prostatic hyperplasia and lower urinary tract symptoms

OBJECTIVE: To evaluate the potential of sildenafil, vardenafil and tadalafil, all phosphodiesterase-5 (PDE-5) inhibitors used for treating erectile dysfunction, for treating benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). MATERIALS AND METHODS: The mRNA expression of the PDE-5 was determined in rat LUT tissues. The PDE-5 inhibitors were also tested in organ-bath experiments and in a partial bladder outlet obstruction (BOO) rat model in vivo. RESULTS: The highest PDE-5 mRNA expression was in the bladder, followed by the urethra and prostate. PDE-5 inhibitors dose-dependently reduced the contraction of the isolated bladder, urethral and prostate strips. The rank order of potency was vardenafil > sildenafil > tadalafil. In human prostate stromal cells vardenafil inhibited cell proliferation and was more effective than tadalafil and sildenafil. In the BOO model, there was a reduction in the non-voiding contractions after bolus intravenous administration of 3 mg/kg sildenafil and vardenafil. CONCLUSION: These results show that PDE-5 is expressed in LUT tissues. PDE-5 inhibitors induced significant relaxation of these tissues, inhibited the proliferation of human prostate stromal cells and reduced the irritative symptoms of BPH/LUTS in vivo. Therefore, PDE-5 inhibitors could be used as an effective treatment for BPH/LUTS.     

8‐isoprostane F2α up‐regulates the expression of type 5 phosphodiesterase in cavernosal vascular smooth muscle cells: inhibition with sildenafil,iloprost, nitric oxide and picotamide

OBJECTIVES

To explore the possible role of of 8‐isoprostane F_2α (8‐IPF_2α) in the aetiology of erectile dysfunction (ED), as the over‐production of superoxide (O₂^‐) derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase results in the formation of 8‐IPF_2α in vascular tissue, which has similar properties to thromboxane A₂ (TXA₂). TXA₂ is vasoconstrictor and up‐regulates the expression of NADPH oxidase and phosphodiesterase type 5 (PDE5).

MATERIALS AND METHODS

Cavernosal vascular smooth muscle cells (CVSMCs) were incubated with 8‐IPF_2α or the TXA₂ analogue, U46619, ±sildenafil, iloprost (a stable prostacyclin [PGI₂] analogue) or the nitric oxide (NO) donor NONOate for 16 h. The formation of O₂^‐ was then measured, PDE5 expression assessed using Western blotting and PGI₂ and 8‐IPF_2α formation measured using enzyme‐linked immunoassays.

RESULTS

8‐IPF_2α promoted the formation of O₂^‐, an effect inhibited by apocynin (an NADPH oxidase inhibitor) and up‐regulated the expression of PDE5. Under identical incubation conditions, 8‐IPF_2α induced an increase in the formation of 8‐IPF_2α but reduced the formation of PGI₂. All, these effects were reversed by sildenafil, iloprost, NONOate and picotamide.

CONCLUSIONS

These data show that O₂^‐ derived from NADPH oxidase influences the relative balance of PGI₂ and 8‐IPF_2α in CVSMCs, which in turn alters the degree of PDE5 expression. This is a novel pathogenic mechanism underlying ED and a novel mechanism of action of sildenafil.     

Insulin generates free radicals by an NAD(P)H, phosphatidylinositol 3'-kinase-dependent mechanism in human skin fibroblasts ex vivo

Oxidative stress may be involved in the development of vascular complications associated with diabetes; however, the molecular mechanism responsible for increased production of free radicals in diabetes remains uncertain. Therefore, we examined whether acute hyperinsulinemia increases the production of free radicals and whether this condition affects proliferative extracellular signal-regulated kinase (ERK-1 and -2) signaling in human fibroblasts in vitro. Insulin treatment significantly increased intracellular superoxide anion (O(2)(-)) production, an effect completely abolished by Tiron, a cell-permeable superoxide dismutase (SOD) mimetic and by polyethylene glycol (PEG)-SOD, but not by PEG catalase. Furthermore, insulin-induced O(2)(-) production was attenuated by the NAD(P)H inhibitor apocynin, but not by rotenone or oxypurinol. Inhibition of the phosphatidylinositol 3'-kinase (PI 3'-kinase) pathway with LY294002 blocked insulin-stimulated O(2)(-) production, suggesting a direct involvement of PI 3'-kinase in the activation of NAD(P)H oxidase. The insulin-induced free radical production led to membranous translocation of p47phox and markedly enhanced ERK-1 and -2 activation in human fibroblasts. In conclusion, these findings provided direct evidence that elevated insulin levels generate O(2)(-) by an NAD(P)H-dependent mechanism that involves the activation of PI 3'-kinase and stimulates ERK-1- and ERK-2-dependent pathways. This effect of insulin may contribute to the pathogenesis and progression of cardiovascular disease in the insulin resistance syndrome.     

Sildenafil extends survival and graft function in a large animal lung transplantation model.

OBJECTIVE: Restoring intracellular cGMP and inducing NO-synthesis attenuates ischemia-associated early pulmonary allograft dysfunction. Phosphodiesterase-5 (PDE), predominantly expressed in lung tissue, plays a pivotal role in modulating the cGMP/NO-synthase pathway in endothelial and epithelial cells. In this study, we evaluate the effect of employing sildenafil (Viagra), a specific inhibitor of PDE-5, to counteract ischemia/reperfusion (I/R) injury in a single lung transplantation model of extended ischemia. METHODS: Donor animals (weight matched outbred pigs, 28-35 kg) in the treatment group (I) (n=5) were injected with 0.7 mg sildenafil/kg into the pulmonary artery (PA) prior to inflow occlusion. For perfusion, Perfadex, containing 0.7 mg sildenafil/l was used, and the graft stored at 1 degrees C in the perfusion solution. After 24h ischemia, unilateral left lung transplantation was performed. Starting at reperfusion, group I received continuous sildenafil (0.7 mg sildenafil/kg), over 6h. Except for the sildenafil application, the control group (II) (n=4) was treated identically (PGE1 was injected into the PA). One hour after reperfusion, the right main bronchus (MB) and right PA were occluded. Over the next 5h, cardiopulmonary parameters (systemic atrial, PA, central venous, left atrial pressure, pCO(2), pO(2)) were measured, including extravascular lung water (EVLW). Thiobarbituric acid-reactive substance assay (TBARS) and myeloperoxidase (MPO) analysis from lung tissue were run. RESULTS: All recipients of group I survived the 6-h reperfusion period; in contrast, all control animals died within 1-2h after occlusion of the right side. In comparison to a marked rise in pulmonary vascular resistance (PVR) in group II (>1000 dynescm(-5)), PVR in group I remained stable, moderately elevated from baseline (baseline: 150-180 dynescm(-5) vs endpoint: 1000 dynescm(-5)). EVLW in group I did not increase during reperfusion (baseline: 6.75+/-1.4 mg/kg vs endpoint: 6.7+/-1.0mg/kg), in contrast to group II, where pulmonary edema at 2-h reperfusion preceded terminal graft failure (group I: 9.7+/-0.1mg/kg vs group II: 6.48+/-1.8 mg/kg). Tissue reactive free radicals at endpoint measurement in group I did not differ significantly from native tissue. Yet, when compared to specimen taken from group II at time of terminal graft failure, a significant increase in free radicals was noted (group I: 13.8+/-1.6 pmol/g vs group II: 18.5+/-3.0 pmol/g, p<0.05). CONCLUSION: Sildenafil treatment prevents terminal early graft failure, allowing lung transplantation after 24-h ischemia time. Reperfusion edema was strikingly diminished, preserving pulmonary structural and functional integrity while prolonging graft ischemia time. Employing the established PDE-5 inhibitor sildenafil during lung perfusion, storage, and implantation, ischemic tolerance may be extended and early graft function improved.     

同期内使用3种PDE5抑制剂治疗ED的经验

目的:观察与比较同期内使用3种PDE5抑制剂治疗ED患者的疗效,满意情况和不良反应。分析影响患者疗效、接受度、倾向性的因素。方法:11个月在门诊应用3种PDE5抑制剂治疗ED患者331例。使用西地那非134例,他达拉非88例,及伐地那非109例。医师详细指导药物的应用,注意事项,观察的内容等,并互留电话,列表登记、随访。结果:复诊或电话随访时间,结果为:①获得良好的疗效及满意率为西地那非72例(79.12%),他达拉非52例(78.78%),伐地那非63例(81.81%)。②PDE5抑制剂单纯或交叉应用的资料分析显示:青年患者或新婚者,偏好伐地那非;③中青年患者倾向于他达拉非;中老年及较长期应用PDE5抑制剂的患者多选用西地那非。3种PDE5抑制剂用于早泄均有一定疗效。④对不能继续用此类药治疗ED的原因进行了分析,分别为:价高,不治本,效果差,耽心不良反应。结论:①同期3种PDE5抑制剂治疗ED的疗效基本相近。亦各有一些优势和特点。②3种PDE5抑制剂的安全性均好,一般、轻度不良反应相近,中度、特殊的不良反应少,严重不良反应均无发生。③PDE5抑制剂的疗效观察,目前众多的问卷、量表实际均仍以主观的感受为主。对同一个人以相同形式、相同问题、繁简一致阐述,获得的有关疗效满意情况、感受等简易回答是有可比性、可信度和实用性的。     

磷酸二酯酶5抑制剂治疗勃起功能障碍的疗效和安全性比较

磷酸二酯酶 5 (PDE 5 )抑制剂西地那非的问世使男性勃起功能障碍 (ED)的治疗手段发生了根本性的改变。1998年以来有 10 0多个国家的 2 0 0 0多万患者使用了西地那非 ,患者的死亡率与总体人群的死亡率差异无显著性。西地那非治疗ED平均有效率达 80 %以上 ,成为治疗ED的首选手段。随着新的PDE 5抑制剂伐地那非和泰地那非在国外先后进入临床使用 ,药物治疗ED有了更多的选择。本文通过比较 3种PDE 5抑制剂的药效学、药动学及不良反应以评价其疗效和安全性。     

The effects of chronic phosphodiesterase-5 inhibitor use on different organ systems

Phosphodiesterase-5 (PDE-5) inhibitors selectively inhibit PDE-5 enzymes that are present in various tissues like penile tissue, platelets, vascular, and smooth muscle tissue. The drug's actions on these tissues have lead to the successful therapeutic use in patients suffering from conditions such as erectile dysfunction (ED) and pulmonary hypertension. PDE-5 inhibitors (PDE-5i) act on the erectile tissue causing penile smooth muscle relaxation and vasodilatation leading to penile erection. In addition, in particular when used in conjunction with prostaglandin inhibitors, PDE-5i cause vasodilatation in pulmonary vasculature hence decreasing both the pulmonary arterial pressure and resistance. PDE-5i have also shown to mildly decrease blood pressure, increase cardiac index, and increase coronary blood flow in experimental animals as well as in human studies. The Food and Drug Administration (FDA) has approved three PDE-5i for the treatment of ED: sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) and one for pulmonary hypertension: sildenafil (Revatio). These agents are highly selective for PDE-5 enzymes as compared to other subclasses of PDE enzymes and have the almost identical pharmacological action but slightly different pharmacokinetics. Only little data exist about long-term use of PDE-5i and their effects on different organ system. This paper reviews the current information available on chronic PDE-5 inhibitor use.     

Apocynin alleviates cisplatin‐induced testicular cytotoxicity by regulating oxidative stress and apoptosis in rats

The aim of this study was to investigate possible protective effects of apocynin (APO), an NADPH oxidase (NOX2) inhibitor, on cisplatin (CIS)‐induced testicular damage. Four groups of Sprague Dawley rats were used: control, APO, CIS and CIS+APO. Following a single intraperitoneal dose of CIS (7 mg/kg), either dimethyl sulfoxide or APO (25 mg/kg) was administered orally for 5 days. Testis samples were evaluated microscopically for general histopathology and ultrastructure, proliferating and apoptotic cells, and NOX2 localization. Sperm parameters were evaluated. Malondialdehyde (MDA) and glutathione (GSH) levels and superoxide dismutase (SOD), myeloperoxidase (MPO) and 8‐hydroxy‐2‐deoxyguanosine (8‐OHdG) activities were analysed biochemically. The CIS group had a greater number of abnormal spermatozoa, atrophic seminiferous tubules, apoptotic and NOX2‐immunoreactive cells; numerous large vacuole formations in the cytoplasm of germinal epithelial cells; degenerated intercellular tight junctions; higher MDA, 8‐OHdG and MPO levels; decreased numbers of spermatozoa; and lower proliferative index and GSH and SOD levels. All these histologic and biochemical results were better in the CIS+APO group. CIS causes testicular damage by decreasing spermatogenic cell lines and increasing NOX2 activity and apoptosis through oxidative stress. APO prevents testicular damage, possibly by its antioxidant effects.     

Efficacy of PDE-5-inhibitors for erectile dysfunction. A comparative meta-analysis of fixed-dose regimen randomized controlled trials administering the International Index of Erectile Function in broad-spectrum populations

This meta-analytic study aims to estimate the likely improvements of erectile dysfunction (ED) measured by the International Index of Erectile Function (IIEF) at the highest fixed dosages of the three available PDE-5-inhibitors: sildenafil, tadalafil, and vardenafil. MEDLINE and the Cochrane Library were searched electronically for efficacy trials of PDE-5-inhibitors for treating ED. In addition drug manufacturers were contacted to provide unpublished or unrecorded congress proceedings. Randomized, double-blind, placebo-controlled, parallel-group, maximum fixed-dose, broad-spectrum efficacy trials using IIEF were included in the analysis. Data were independently extracted by two reviewers. The results were pooled using weighted mean differences. A formal indirect comparison (including Bonferroni-correction) was conducted to estimate the differences between agents. A total of 14 trials were included in the meta-analysis (three with 100 mg sildenafil, eight with 20-25 mg tadalafil, and three with 20 mg vardenafil). All trials were of good methodological quality. Overall heterogeneity was moderate: I(2)=33.2%, chi(2)=19.47, P=0.11. The funnel plot suggested moderate likelihood of publication bias. Pooled results of IIEF-improvement were for sildenafil 9.65 (95% CI: 8.50, 10.79) points, tadalafil 8.52 (7.61, 9.42) points, and vardenafil 7.50 (6.50, 8.50) points, respectively. Sildenafil proved to be significantly more effective than vardenafil (d=2.15, P=0.006), other pairwise comparisons showed no difference in efficacy. All PDE-5-inhibitors are highly effective in the treatment of ED. At maximum dosage they improve erectile function 7-10 points on the IIEF compared to placebo-treatment. There is evidence that sildenafil might be more efficacious than vardenafil, although this is to be interpreted with caution. To prove higher efficacy truly independent comparative trials are needed.     

Early treatment with cGMP phosphodiesterase inhibitor ameliorates progression of renal damage

BACKGROUND: Chronic renal disease is associated with oxidative stress and reduced nitric oxide availability which, in turn, promotes hypertension and further progression of renal damage. Most actions of nitric oxide are mediated by cyclic 3',5' guanosine monophosphate (cGMP) which is rapidly degraded by phosphodiesterases (PDE). Therefore, we investigated if inhibition of PDE-5 would retard the progression of chronic renal failure. METHODS: We studied rats with 5/6 nephrectomy treated with sildenafil (2.5 mg/kg(-1)/day(-1)) in two experimental protocols. In the first protocol, we started sildenafil therapy immediately after renal ablation and continued treatment for 8 weeks. Control groups consisted of rats with renal ablation treated with drug-free vehicle and sham-operated rats with and without sildenafil treatment. RESULTS: In these studies, sildenafil treatment prevented hypertension and deterioration of renal function, reduced histologic damage, inflammation and apoptosis, delayed the onset of proteinuria, and preserved renal capillary integrity. In the second protocol we compared sildenafil with losartan (7.5 mg/kg(-1)/day(-1)) and the combination of both drugs in established renal disease, starting these drugs 4 weeks after 5/6 nephrectomy. Delayed sildenafil treatment failed to improve proteinuria and glomerulosclerosis but ameliorated hypertension and azotemia. CONCLUSION: These observations suggest that currently available PDE-5 inhibitors have potential clinical value in the treatment of chronic renal disease.     

Sildenafil: emerging cardiovascular indications

The discovery in 1989 of sildenafil, a highly selective inhibitor of phosphodiesterase-5 (PDE-5), was the result of extensive research on chemical agents targeting PDE-5 that might potentially be useful in the treatment of coronary heart disease. Initial clinical studies on sildenafil in the early 1990s were not promising with respect to its antianginal potential. However, the incidental discovery of its antiimpotence effect led to its approval of for the treatment of erectile dysfunction. Thereafter, several reports of adverse cardiac events in patients on sildenafil raised concerns about its safety in cardiovascular disorders. Novel therapeutic indications are emerging for sildenafil with the recent discovery that PDE-5 is expressed in various other tissues such as the arterial vasculature, including pulmonary and coronary arteries, venous vasculature, skeletal muscles, platelets, and visceral and tracheobronchial muscles. In this review we briefly summarize the pharmacology of sildenafil and the current available evidence on its potential therapeutic applications in cardiovascular disorders.     

Melatonin decreases apoptosis and expression of apoptosis-associated proteins in acute puromycin aminonucleoside nephrosis.

BACKGROUND: The anti-apoptotic properties of melatonin have been demonstrated previously in several in vivo and in vitro studies. Previous reports have shown increased apoptosis during puromycin aminonucleoside nephrosis (PAN). The aim of this study was to determine if melatonin (MEL) can prevent apoptosis and modify oxidative stress, an apoptosis inducer, in this experimental model. METHODS: Rats were injected intraperitoneally with puromycin aminonucleoside. In addition, by the intragastric route they received 1 mg/kg/day of MEL or vehicle 3 days before puromycin injection and throughout the experiment. Animals were sacrificed at weeks 1 and 2 of nephrosis and frozen renal sections were studied for apoptosis by TUNEL, for apoptosis-associated proteins by monoclonal and polyclonal antibodies, and for superoxide anion (O(2)(-)) by a histochemical method. Nitric oxide (NO), malondialdehyde (MDA) and reduced glutathione (GSH), and the activities of superoxide dismutase (SOD) and catalase were measured in homogenized kidney tissue by appropriate biochemical and enzymatic methods. RESULTS: Increases in apoptosis, p53, Fas and Fas-ligand were observed in nephrotic animals. MEL treatment decreased apoptosis at weeks 1 and 2 in the glomerular, interstitial and tubular compartments. This was accompanied by decreased expression of p53 (glomerulus, week 1; tubules, weeks 1 and 2), Fas (glomerulus and interstitium, week 2; tubules, weeks 1 and 2) and Fas-ligand (interstitum and tubules, week 2). Increased expression of Bcl-2-positive cells was observed at week 2 in all renal compartments in MEL-treated animals. High levels of O(2)(-) and NO generation and lipid peroxidation (MDA) were found in nephrotic animals. SOD and GSH remained unchanged, and only decreased catalase activity (week 1) was observed in PAN animals. Tendencies toward decreased values of O(2)(-) and MDA content along with recovery of catalase activity (week 1) were observed in MEL-treated nephrotic animals, but were insignificant in magnitude. MEL, however, did significantly downregulate pro-apoptotic genes and upregulated anti-apoptotic genes. CONCLUSIONS: The data demonstrate that, in PAN, melatonin has anti-apoptotic effects, which might in part be independent of the modulation of the oxidative status.     

Exploring the potentials of some compounds from Garcinia kola seeds towards identification of novel PDE-5 inhibitors in erectile dysfunction therapy

Erectile dysfunction (ED) is one of the main challenges occurring among men worldwide, and is characterised by trouble getting or keeping steady erection during sexual intercourse. Various drugs like sildenafil, a phosphodiesterase-5 inhibitor (PDE-5) are freely available in the pharmacies, though normally associated with several adverse. This study was designed to assess the molecular relations obtainable between catechin, garcinal, garcinoic acid and d-tocotrienol compounds isolated from Garcinia kola and targeted receptor linked to ED. These processes include the molecular docking of catechin, garcinal, garcinoic acid, d-tocotrienol, and sildenafil to receptor: PDE-5 via AutoDock Vina. Following the docking of catechin, garcinal, garcinoic acid and d-tocotrienol with the PDE-5-receptor protein, we observed that all are protein inhibitors with garcinoic acid showing better binding affinity −10.0 kcal/mol with PDE-5 receptor relevant to ED. Hence, the results provided insights into the development of garcinoic acid as a replacement for present ED management, with further analysis worth considering.     

Molecular mechanisms and pharmacokinetics of phosphodiesterase-5 antagonists

The prominence of phosphodiesterase-5 (PDE-5) inhibitors in the treatment of male erectile dysfunction and other diseases related to vascular dysfunction mandates a comprehensive understanding of the properties and effects of these compounds. Three potent and selective PDE-5 inhibitors (sildenafil, tadalafil, and vardenafil) have been approved for clinical use. The clinical efficacy and safety profiles of these medications are related to their molecular mode of action, the selectivity for PDE-5, and the pharmacokinetic properties (absorption, bioavailability, time to onset of action, distribution, metabolism, and elimination). These PDE-5 inhibitors share some common properties with regard to mechanisms of action and selectivities for PDE-5. They also have distinctive characteristics that may impact their clinical use. This article focuses on the basic biochemistry of cyclic guanosine monophosphate signaling and the pharmacokinetic parameters that describe characteristics of drug action of these PDE-5 inhibitors in facilitating smooth muscle relaxation, leading to improved penile erectile response or causing side effects.     

Effects of sildenafil and vardenafil treatments on sleep quality and depression in hemodialysis patients with erectile dysfunction

ED is prevalent in hemodialysis (HD) patients, and closely related to poor sleep and depression. Efficacy of treating ED either with sildenafil or vardenafil has been shown to be beneficial in ameliorating concomitant depression in non-HD patients. It is yet to be shown whether treatment of ED with a PDE-5 inhibitor would improve poor sleep in HD patients. We aimed to compare the effects of sildenafil and vardenafil on sleep quality and depression in HD patients with ED. A total of 32 maintenance HD patients with ED randomized into two groups to receive either sildenafil or vardenafil for 4 weeks. After a 2-week washout and a crossover, each group received the other drug for another 4-week period. Sleep quality and depression were evaluated via post-sleep inventory (PSI) and Beck's depression inventory (BDI), respectively, at baseline and at the end of the treatment. Sildenafil and vardenafil both improved PSI and BDI scores significantly compared with pretreatment values. However, there was no difference between sildenafil and vardenafil with respect to these parameters. PDE-5 inhibitors, sildenafil and vardenafil, caused a significant improvement in sleep quality and depression in this cohort of HD patients with ED.     

Erectile dysfunction secondary to nerve-sparing radical retropubic prostatectomy: Comparative phosphodiesterase-5 inhibitor efficacy for therapy and novel prevention strategies

Postprostatectomy erectile dysfunction appears to be initiated by neuropraxia and perpetuated by cavernosal smooth muscle apoptosis. Phosphodiesterase-5 (PDE-5) inhibitor therapy is the current cornerstone of erectile dysfunction (ED) therapy in this population. Although no head-to-head trials have been performed with sildenafil, vardenafil, and tadalafil in this population, there are numerous studies in the general ED population. The results of these studies demonstrate that neither of the new PDE-5 inhibitors met statistical noninferiority to sildenafil. Sildenafil has been studied in a novel primary prevention modality using nightly administration after a bilateral nerve-sparing prostatectomy. In this novel approach, it effected a sevenfold improvement in return of spontaneous, normal erectile function 2 months after drug discontinuation. This effect appears to be mediated by properties unique to sildenafil that include improved endothelial function and neuronal regeneration and neuroprotection. In primary prevention, unlike ED therapy, one has only “one shot” by definition. Therefore, it is even more critical to apply evidence-based medicine.