Erectile potentials of a new phosphodiesterase type 5 inhibitor, DA-8159, in diet-induced obese rats

Aim： To examine the changes in the erectile function in diet-induced obese rats and investigate the oral efficacy of DA-8159, a new phosphodiesterase type 5 （PDE5） inhibitor, on penile erection in obese rats. Methods： The rats were fed a high-energy diet for 12 weeks and divided into three groups： an obesity-resistant （OR） control group, an obesity-prone （OP） control group, and an OP-DA-8159 treatment （DA-8159） group. The electrostimulation-induced erectile responses were measured in all groups. The body weight, plasma cholesterol, triglyceride and glucose levels were also measured. Results： In the OP control group, the maximum intracavernous pressure （ICP） and ICP/blood pressure （ICP/BP） ratio after electric stimulation were significantly lower than those in OR control group. The corresponding area under the curve （AUC） of the ICP/BP ratio, the detumescence time and the baseline cavernous pressure were also lower than those in the OR control group, but this difference was not significant. The body weight gain, plasma cholesterol and triglyceride level in the OP group were significantly higher than those in the OR group. After administering the DA-8159, a significant increase in the maximum ICP and the ICP/BP ratio were observed. The corresponding AUCs in the DA-8159 group were also higher than those in the two control groups. Furthermore, the detumescence time was significantly prolonged after treatment with DA-8159. Conclusion： These results demon- strate that diet-induced obesity affects the erectile function in rats and these erectile dysfunction （ED） can be improved by the treatment with DA-8159, indicating DA-8159 might be a treatment option for ED associated with obesity.     

糖尿病性勃起功能障碍大鼠阴茎海绵体组织中神经生长因子的表达及其治疗作用的研究

目的:本研究通过检测糖尿病性勃起功能障碍(ED)大鼠阴茎组织中神经生长因子(NGF)表达,并使用hNGF进行治疗,以探讨糖尿病性ED发病机制及NGF治疗作用的机制。方法:成年雄性SD大鼠60只,随机取50只大鼠用于制作糖尿病模型,饲养8周后,取正常组和糖尿病组大鼠阴茎海绵体组织,采用RT-PCR和W estern印迹法检测NGF的mRNA及蛋白水平。从造模成功的糖尿病大鼠中筛选出有ED大鼠,把所有大鼠分为5组:正常组、糖尿病性ED组、糖尿病性ED单用NGF组(NGF组)、糖尿病性ED单用胰岛素组(R I组)、糖尿病性ED联合应用NGF和胰岛素组(NGF+R I组,胰岛素通过颈部皮下注射给药,NGF通过腹腔内注射给药),8周后测海绵体内压(ICP),并取所有大鼠阴茎海绵体组织用免疫组化法观察nNOS神经纤维的变化。结果:与正常组相比,糖尿病性ED组大鼠阴茎海绵体组织中NGF的mRNA表达增加,蛋白含量增加。与糖尿病性ED组相比,NGF组、R I组、NGF+R I组ICP水平显著升高(P<0.05);NGF组、R I组、NGF+R I组阴茎组织中nNOS神经纤维水平显著升高(P<0.05)。结论:糖尿病晚期勃起神经出现损伤并发生ED,推测可能与NGF分泌增加的幅度小于高血糖状态对勃起神经的损伤程度有关,也可能与NGF与其相应受体结合转运能力损害有关,给予外源性NGF可能有助于糖尿病性ED局部神经病变减轻和勃起功能改善。提示NGF的异常在糖尿病性ED的发病及治疗中可能具有重要作用。     

脂肪来源干细胞促进糖尿病ED勃起功能恢复的实验研究

目的观察脂肪来源干细胞(adipose-derived stem cells, ASCs)对糖尿病大鼠勃起功能障碍(erectile dysfunction, ED)的治疗作用,研究其改善勃起功能的机制。方法取12周龄性成熟的30只雄性SD大鼠,随机分成3组(每组10只),A组为正常组(血糖正常的SD大鼠),B组为PBS组(糖尿病ED大鼠单纯注射PBS治疗),C组为ASCs组(糖尿病ED大鼠海绵体注射ASCs治疗)。治疗12周后测定阴茎海绵体内压(intracavernous pressure, ICP)和平均动脉压(mean arterial pressure, MAP),Masson染色检测海绵体平滑肌/胶原显微比例,CD31免疫荧光染色检测血管数量。结果 PBS组的平滑肌/胶原比例显著低于正常组(P0.001),ASCs组平滑肌/胶原纤维比例较PBS组增高,差异有统计学意义(P0.001)。ICP/MAP结果显示,ASCs组ICP/MAP为(0.6896±0.0260),较PBS组(0.3724±0.0137)显著升高(P0.001)。CD31荧光显示PBS组血管数量明显降低(P0.001),而ASCs组血管数量显著高于PBS组。结论ASCs能够通过促进血管及平滑肌再生,来改善糖尿病大鼠的勃起功能,提示ASCs是潜在的糖尿病ED的治疗手段。     

PDE_5基因特异性siRNA改善糖尿病性勃起功能障碍大鼠勃起功能的研究

目的 探讨人鼠PDEs基因siRNA对糖尿病性勃起功能障碍(DM ED)大鼠PDE,基因表达的抑制作用及其对DMED大鼠勃起功能的影响.方法 构建可同时表达2条针对大鼠PDEs基因的shRNA重组腺病毒;50只雄性SD大鼠随机取10只作为正常对照.其余建立DM ED人鼠模型,随机分为实验组、阴性对照组和空白对照组,分别将重组腺病毒rAd-rPDEs-shRNA、腺病毒rAd-mock及生理盐水注射于阴茎海绵体.注射后第7天,电刺激盆神经测定各组大鼠阴茎海绵体内压(ICP)及平均周围动脉压(MAP),然后取海绵体组织通过RT-PCR和Western blot分别检测PDE5基因mRNA及蛋白的表达.结果 ICP/MAP实验组和正常对照组显著高于阴性对照组和窄白对照组(P＜0.05),实验组和正常对照组间无显著性差异(P＞0.05);RT-PCR和Western blot 分析,实验组大鼠PDE5基因mRNA和蛋白表达均显著低于阴性对照组和空白对照组(P＜0.05).结论 PDE5基因shRNA重组腺病毒转染可以改善DMED大鼠的勃起功能,为DMED治疗方法的探索提供了新的思路.     

骨髓间充质干细胞即刻与延时治疗修复阴茎海绵体神经损伤大鼠勃起功能的研究

目的:拟观察在双侧阴茎海绵体神经(CN)损伤的大鼠神经性勃起功能障碍(NED)模型中即刻和延时向阴茎海绵体注射骨髓间充质干细胞(BM-MSCs)对大鼠阴茎勃起功能的修复作用。方法:选取28只8周龄、体重200~250 g雄性SD大鼠随机分为4组:假手术组找到双侧海绵体神经后不做处理直接关腹并缝合皮肤;对照组、即刻治疗组和延时治疗组均通过钳夹的方式损伤双侧阴茎海绵体神经建立NED模型随后关腹缝合。假手术组和对照组向阴茎海绵体内注射对照剂,即刻治疗组注射BM-MSCs,延时治疗组术后两周注射BM-MSCs。术后12周采用电刺激CN记录阴茎海绵体内压(ICP),颈动脉穿刺测定平均动脉压(MAP),ICP/MAP作为勃起功能的评价指标来评估大鼠的勃起功能。在勃起功能检测后处死大鼠,取阴茎海绵体中段组织检测平滑肌、胶原和神经纤维。结果:在手术后12周,即刻治疗组和延时治疗组ICP和ICP/MAP均较对照组升高(P0.05)。即刻治疗组和延时治疗能提高大鼠海绵体组织内平滑肌与胶原的比例(P0.05),同时两组阴茎海绵体内平滑肌含量高于对照组(P0.05),阴茎海绵体背神经内神经微丝(NF)蛋白阳性神经纤维数目和nNOS的表达高于对照组(P0.05)。结论:阴茎海绵体内注射BM-MSCs能对双侧CN损伤大鼠的勃起功能恢复有促进作用。BM-MSCs治疗可以提高海绵体组织内平滑肌与胶原的比例,改善纤维化,并能提高海绵体组织中平滑肌含量、阴茎背神经的神经丝含量和nNOS的表达水平,术后延时治疗同样能取得一定的治疗效果。     

左旋精氨酸对糖尿病大鼠阴茎海绵体氧化应激损伤的保护作用

目的 探讨左旋精氨酸(L-Arg)对糖尿病大鼠阴茎海绵体氧化应激损伤的保护作用.方法 大剂量STZ腹腔注射建立糖尿病大鼠模型,随机分为糖尿病组、L-Arg治疗组,并设正常对照组.治疗8周后用电刺激各组大鼠勃起神经测定海绵体内压评价勃起功能采用黄嘌呤氧化酶法检测阴茎海绵体组织中超氧化物歧化酶(SOD)活性,硫代芭比妥酸法测丙二醛(MDA)含量;光镜下观察Masson染色切片.结果 糖尿病组较正常对照组,阴茎海绵体MDA含量显著增高(P<0.01),SOD活性显著下降(P<0.05),最大海绵体内压(ICP)显著降低(P<0.05);与糖尿病组比较,L-Arg可使海绵体MDA含量明显降低(P<0.05),显著提高其SOD活性及ICP(P<0.05).糖尿组大鼠阴茎组织中胶原纤维含量明显减少,排列紊乱、稀疏,平滑肌减少变薄,出现断裂;L-Arg组大鼠阴茎组织结构可见明显改善.结论 糖尿病大鼠阴茎海绵体存在氧化应激损伤,导致海绵体结构的改变是其勃起水平下降的重要因素,通过补充L-Arg,可以减轻勃起组织的氧化应激损伤,改善组织结构,从而提高勃起能力.     

大鼠衰老过程中勃起功能改变与去乙酰化酶SIRT1的关系研究

目的:研究衰老过程中大鼠勃起功能变化、抗衰老蛋白SIRT1表达及其相关因子改变,探索SIRT1与老年性勃起功能障碍(ED)发生的关系。方法:SD大鼠按不同月龄分组,利用电刺激大鼠盆腔星状神经节法测定阴茎海绵体内压(ICP),颈动脉穿刺测定平均动脉压(MAP),ICP/MAP作为勃起功能的评价指标;马松染色观察胶原纤维变化;Western印迹测定不同月龄大鼠阴茎海绵体中SIRT1、P53及FOXO3a的表达变化;NO、c GMP检测试剂盒测定阴茎海绵体中NO、c GMP含量。结果:随月龄增长,大鼠勃起功能(ICP/MAP)在8月龄达到峰值,其后随月龄增长降低。c GMP含量变化与勃起功能一致。随月龄增加,大鼠阴茎海绵体中胶原纤维增多。SIRT1的表达随月龄增加不断降低;而凋亡因子P53、氧化应激因子FOXO3a的表达随月龄增加不断上升。结论:NO/c GMP通路活性降低、凋亡及氧化应激可能是衰老导致ED的原因。抗衰老蛋白SIRT1与其调控的凋亡、氧化应激因子改变与勃起功能一致,推测SIRT1与老年性ED的发病有关。     

IGF-1基因治疗提高老龄大鼠阴茎海绵体平滑肌密度的研究

目的 观察阴茎海绵体内注射胰岛素样生长因子-1 (IGF-1)基因能否提高老年性大鼠阴茎勃起功能及其对阴茎海绵体平滑肌密度的影响,以探讨IGF-1基因治疗ED的机制.方法 4月龄SD雄性大鼠(青年组)10只;24月龄SD雄性大鼠(老龄组)20只,随机分为2组:PBS对照组、100 μg IGF-1质粒注射组.每组10只注射后8周行电刺激检测大鼠阴茎海绵体内压(ICP)和平均动脉压(MAP),分析比较IGF-1基因治疗的效果,Masson,s三色染色图文定量分析阴茎海绵体平滑肌在海绵体组织中含量的变化.结果 电刺激发现老龄组较青年组ICP/MAP和总ICP明显降低(P＜0.05).IGF-1基因治疗8周后,100 μg IGF-1质粒注射组较PBS对照组ICP/MAP和total ICP均明显提高(P＜0.05);阴茎海绵体平滑肌的含量在老龄组较青年组明显降低(P＜ 0.05);与PBS对照组比较,100μg IGF-1质粒注射组能够明显提高阴茎海绵体平滑肌的含量(P＜0.05).结论 I GF-1基因治疗能够改善老龄大鼠的勃起功能,其作用机制之一可能是通过提高阴茎海绵体平滑肌的含量.     

褪黑素抗氧化治疗糖尿病大鼠阴茎勃起功能障碍的研究

目的 观察褪黑素对糖尿病大鼠阴茎勃起功能的影响,探讨氧化应激在糖尿病性勃起功能障碍发病机制中的作用.方法 一次性腹腔注射STZ建立糖尿病大鼠模型,随机分为糖尿病组、褪黑素(MT)治疗组以及对照组.8周后通过电刺激各组大鼠勃起神经来检测海绵体内压,评价勃起功能;采用硫代芭比妥酸法检测阴茎海绵体组织中丙二醛(MDA)含量,黄嘌呤氧化酶法测超氧化物氧化酶(SOD)活性;免疫组化染色半定量分析各组大鼠阴茎海绵体中平滑肌及内皮的含量.结果 与正常对照组相比,阴茎海绵体组织中MDA含量显著增加(P＜0.01),SOD活性降低(P＜0.05),最大海绵体内压(ICP)亦显著降低(P＜0.05);与糖尿病组相比,MT组大鼠海绵体MDA含量明显降低(P＜0.05),其SOD活性和ICP显著升高(P＜0.05);且其海绵体平滑肌及海绵窦内皮细胞含量明显提高.结论 MT可通过改善组织中氧化应激水平,促进阴茎海绵体平滑肌和内皮组织修复,提高勃起功能;抗氧化治疗可能为糖尿病性勃起功能障碍的防治提供新的策略.     

HHcy大鼠tHcy与阴茎海绵体内NOS和H_2S的相关性研究

目的探讨甜菜碱(Betaine,Bet)对高同型半胱氨酸血症(HHcy)大鼠血浆总同型半胱氨酸(tHcy)及阴茎海绵体内一氧化氮合酶(NOS)、硫化氢(H_2S)及勃起功能的影响。方法选用Wistar雄性大鼠45只,随机选出10只为对照组(A)。其余用3%蛋氨酸喂养,造模成功后的30只,随机分为:高同型半胱氨酸组(B)、盐酸甜菜碱治疗组(C)、叶酸、维生素B12治疗组(D)。A组给予正常饲料;B组3%蛋氨酸喂养。C组、D组,在喂养3%蛋氨酸的同时,分别给予Bet和叶酸、维生素B12灌胃。4周后,进行APO实验、大鼠阴茎海绵体内压(ICP)的测定、检测tHcy浓度及阴茎海绵体内NOS活性及H_2S浓度。结果与A组比较,B组tHcy升高、阴茎海绵体内NOS活性及H_2S浓度降低,ICP压力减低,勃起次数减少,有差异性,具统计学意义(P0.05)。C、D组与B组比较,tHcy降低、阴茎海绵体内NOS活性及H_2S浓度增高,ICP压力增高,勃起次数增多(P0.05),同型半胱氨酸(Hcy)与NOS(r_A=-0.857、r_B=-0.976、r_c=-0.903、r_D=-0.847)和H_2S(r_A=-0.857、r_B=-0.976、r_c=-0.903、rD=-0.847)均成负性相关。C组与D组比较,tHcy降低、阴茎海绵体内NOS活性及H_2S浓度升高,ICP压力增高,勃起次数增加,差异具统计学意义(P0.05)。结论 tHcy升高影响阴茎海绵体内NOS活性及H_2S浓度的降低是引发勃起功能障碍(Erectile dysfunction,ED)的机制之一。Bet是治疗HHcy所致ED的有效药物之一。     

Penile erectile responses to electric stimulation are enhanced by a new phosphodiesterase type-5 inhibitor

AIM: This study was conducted to investigate the effect of DA-8159, a new phosphodiesterase type-5 (PDE5) inhibitor, on electrostimulation-induced penile erection in rats. METHODS: Intracavernous pressure (ICP) and arterial blood pressure (BP) were simultaneously recorded through electric pelvic-ganglion stimulation (2-10 Hz) after the oral administration of DA-8159 (3 or 10 mg/kg) in normal and streptozotocin-induced diabetic rats. Statistical analysis was performed on the maximal intracavernous pressure (ICP), detumescence time, maximal intracavernous pressure/blood pressure (ICP/BP) ratio, and the area under the curve (AUC) of the ICP/BP ratio. RESULTS: In normal and diabetic rats, electrical stimulation of the pelvic ganglion induced a frequency- and dose-dependent increase in the intracavernous pressure. The ICP/BP ratio and the corresponding AUC values were also significantly and dose-dependently increased after DA-8159 administration. In addition, the detumescence time significantly increased after DA-8159 administration compared to that of the controls. CONCLUSIONS: These results show that the DA-8159 significantly increased the intracavernous pressure response and prolonged the decay period induced by electrical stimulation of the pelvic ganglion, and suggest that DA-8159 might be a potential therapeutic agent for the treatment of erectile dysfunction.     

The effect of DA-8159, a novel PDE5 inhibitor, on erectile function in the rat model of hypercholesterolemic erectile dysfunction

This study examined the effects of a new phosphodiesterase type 5 inhibitor, DA-8159, on erectile function associated with hypercholesterolemia. First of all, in order to investigate whether chronic administration of DA-8159 prevents the development of erectile dysfunction associated with hypercholesterolemia, male SD rats were divided into four groups (normal control, hypercholesterolemic control, DA-8159 5 or 20 mg/kg/day). Over a 5-month period, the animals were fed a 2% cholesterol diet and administered DA-8159 orally once a day. After 5 months, the electrostimulation-induced penile erection and the vascular function using acetylcholine-induced vasodilation with endothelium-intact aortic rings were examined. Furthermore, the plasma lipid profiles, endothelin and N(G),N(G)-dimethylarginine (asymmetrical dimethylarginine, ADMA) concentrations were measured. In order to investigate the acute treatment effect of DA-8159 on the erectile function in an established hypercholesterolemic model, additional animals were given a 2% cholesterol diet for 5 months without DA-8159. At the end of 5 months, the rats were divided into three groups (hypercholesterolemic control, DA-8159 0.3 or 1 mg/kg). DA-8159 was administered intravenously 1 min prior to the intracavernous pressure (ICP) measurement. In a chronic treatment study, while the hypercholesterolemic control showed a significantly lower erectile function, vascular reactivity, and increased plasma cholesterol, endothelin and ADMA concentration, the chronic DA-8159 treatment clearly restored the erectile responses by electric stimulation, preserved the potential of thoracic aortic relaxation in a dose-dependent manner, and significantly decreased the plasma endothelin and ADMA concentrations. In an acute treatment study, DA-8159 induced a dose- and frequency-dependent increase in ICP. The ICP/BP ratio and the corresponding AUC values, and the detumescence time were also significantly increased compared to the hypercholesterolemic control. These results suggest that DA-8159 is beneficial for erectile dysfunction in a rat hypercholesterolemic model and provided a rationale for the potential use of DA-8159 for treating erectile dysfunction secondary to hypercholesterolemia.     

The effect of PDE5 inhibition on the erectile function in streptozotocin-induced diabetic rats

The aim of this study was to assess the effect of phosphodiesterase 5 inhibitor, DA-8159, on erectile function throughout the quantitative analysis of vascular endothelial cell, smooth muscle (SM), TGF-beta1 expression in rat corpus cavernosum and measurement of intracavernous pressure (ICP) in diabetic rats. DA-8159 (0, 5, 10, 20 mg/kg) was administered orally once a day to diabetic rats. After 8 weeks, immunohistochemistry and computerized image analysis were performed to quantify the percent area within the Corpora Cavernosa occupied by the endothelial cells, SM cells and fibrotic tissues. ICP/mean arterial pressure (MAP) was also measured by electrostimulation of the cavernous nerve. Diabetic rats showed a significant decrease in the SM and endothelial cell content, and an increase in the TGF-beta1 expression level within the cavernosa areas compared to the normal rats. The mean cavernous SM, endothelial cell content and TGF-beta1 expression level were 9.7+/-0.7, 4.5+/-0.7 and 17.9+/-2.1%, respectively. DA-8159 prevented reduction of SM (12.3+/-0.4% (5 mg/kg), 13.8+/-0.4% (20 mg/kg)) and endothelial cell content (5.6+/-0.5% (5 mg/kg), 6.3+/-0.6% (20 mg/kg)). Immunoreactivity of TGF-beta1 and intracorporal fibrosis were also significantly lower in DA-8159-treated groups (11.8+/-1.2% (5 mg/kg), 9.5+/-1.1% (20 mg/kg)). Electrostimulation of the cavernous nerve induced significant increase in maximum ICP (62.2+/-13.6 mmHg in 10 mg/kg vs 37.5+/-17.5 mmHg in diabetic group) and area under the curve of the ratio of ICP/MAP (8891.09+/-1957 in 10 mg/kg vs 6315.87+/-2272 in diabetic group). These results suggest that subchronic treatment of DA-8159 can prevent the development of erectile dysfunction (ED), and provides a rationale for the use of DA-8159 as treatment of diabetic ED.     

Chronic administration of phosphodiesterase 5 inhibitor improves erectile and endothelial function in a rat model of diabetes

This study was conducted to determine if the long-term administration of the phosphodiesterase type 5 (PDE 5) inhibitor, DA-8159, to diabetic rats can ameliorate the development of erectile dysfunction (ED) and endothelial dysfunction. After inducing diabetes with streptozotocin, DA-8159 was orally administered at a dose of 3 mg/kg or 10 mg/kg for 8 weeks. To examine the effect on erectile response, electrostimulation of the cavernous nerve with the parameters of 3 V, 5 ms, 5 Hz or 10 Hz, was performed to measure the intracavernous pressure (ICP) and mean arterial pressure (MAP). Thoracic aorta relaxation in vitro was evaluated by adding acetylcholine (Ach) cumulatively to the bathing medium. In addition, the plasma endothelin-1 (ET-1) levels were measured in order to investigate the effect of DA-8159 on endothelial dysfunction. The area under the curve (AUC) from the ICP/MAP ratio in the 10 Hz stimulation showed a significantly increased AUC after the 10 mg/kg treatment compared with the diabetic group (8891 +/- 619 vs. 6316 +/- 1016, respectively, p < 0.05). At the 5 Hz frequency, DA-8159 10 mg/kg also induced a significant increase in the AUC compared with the diabetic control. The maximum ICP/MAP ratio (%) of the 10 mg/kg treatment group was significantly higher in both the 10 Hz and 5 Hz frequency groups (p < 0.05). A treatment of 3 mg/kg tended to increase the AUC and peak ICP/MAP but was not statistically significant. The Ach EC50 value of the diabetic group was significantly higher than in the normal control (120.50 +/- 22.90 nm vs. 86.80 +/- 9.30 nm, respectively), and 10 mg/kg treatment group showed a significantly lower EC(50) value (88.38 +/- 19.7 nm). The ET-1 level was lower in groups treated with DA-8159, 3 mg/kg and 10 mg/kg treatment induced a statistical difference compared with the diabetic control (1.15 +/- 0.34 fmol/mL vs. 2.51 +/- 0.55 fmol/mL, respectively, p < 0.05). These results demonstrate that chronic administration of DA-8159 could attenuate the development of the ED in diabetes and its effect is associated with an improvement in the endothelial function.     

DA-8159, a new PDE5 Iihibitor,induces penile erection in conscious and acute spinal cord injured rabbits

OBJECTIVES: DA-8159 is a pyrazolopyrimidinone derivative showing potent and selective phosphodiesterase 5 (PDE5) inhibition. In the previous study, DA-8159 induced a dose-dependent increase in the intracavernous pressure (ICP) in anaesthetized dogs. The aim of this study was to investigate the effects of DA-8159 on penile erection in conscious and acute spinal cord injured (ASCI) rabbits. METHODS: DA-8159 was given orally (0.3 to 10mg/kg) to normal rabbits and ASCI rabbits with a surgical transection of the spinal cord at the L2-L4 lumbar vertebra or ischemic-reperfusion. The erection was evaluated in a time-course manner by measuring the length of the uncovered penile mucosa in the absence or presence of intravenous sodium nitroprusside (SNP), a nitric oxide (NO) donor. RESULTS: DA-8159 induced a dose-dependent penile erection in both the conscious and ASCI rabbits. The efficacy of DA-8159 was potentiated and the effective doses were significantly decreased by an intravenous injection of SNP. Potentiation of the effect by a nitric oxide donor implies that DA-8159 can enhance the erectile activity during sexual arousal. CONCLUSION: These results demonstrate that DA-8159 may be a useful treatment option for erectile dysfunction in patients with or without a spinal cord injury, but further evaluation of the effects of DA-8159 on humans must be performed.     

Efficacy of DA-8159, a new PDE5 inhibitor, for inducing penile erection in rabbits with acute spinal cord injury

DA-8159 is a pyrazolopyrimidinone derivative which exhibits potent and selective phosphodiesterase type 5 (PDE5) inhibition. The aim of this study was to investigate the effects of DA-8159 on inducing a penile erection in rabbits with an acute spinal cord injury (ASCI). DA-8159 was given either orally (1, 3, or 10 mg/kg) or intravenously (0.1 or 0.3 mg/kg) to conscious male albino rabbits with a surgical transection of the spinal cord at the L2-L4 lumbar vertebra or ischemic-reperfusion SCI rabbits. Erection was evaluated in a time-course manner by measuring the length of the uncovered penile mucosa. DA-8159 induced a dose-dependent erection in both transection and ischemic-reperfusion ASCI rabbits. The efficacy of DA-8159 was potentiated by an intravenous injection of sodium nitroprusside, a nitric oxide donor. Potentiation of the effect by nitric oxide donor implies that DA-8159 can enhance the erectile activity during sexual arousal. These results suggest that DA-8159 may be useful for treating erectile dysfunction in patients with an SCI.     

Effects of phosphodiesterase type 5 inhibitor on the contractility of prostate tissues and urethral pressure responses in a rat model of benign prostate hyperplasia

AIM: This study was performed to investigate the effect of DA-8159, a selective phosphodiesterase 5 (PDE5) inhibitor, on benign prostatic hyperplasia (BPH) both in vitro and in vivo. METHODS: We assessed the influence of DA-8159 on the contractility of rat prostate tissues in an organ-bath experiment. In addition, in order to investigate whether chronic administration of DA-8159 prevents the increase of electrostimulation-induced intraurethral pressure (IUP) responses associated with BPH, BPH was induced by steroid hormones (testosterone plus 17beta-estradiol) and DA-8159 (5, 20 mg/kg) was concomitantly administered once a day for 8 weeks. After that the electrostimulation-induced IUP responses were measured. Finally, we investigated the acute treatment effect of DA-8159 on IUP responses in an established BPH model after a single intravenous injection of DA-8159 (0.3, 1 mg/kg). RESULTS: DA-8159 concentration-dependently reduced the contraction of the isolated prostate strips with an IC50 value of 70 microM. In chronic treatment study, while the BPH control rats showed a significantly increased IUP both at the baseline and by electrostimulation, the chronic DA-8159 treatment significantly attenuated the increase in IUP responses in a dose- and frequency-dependent manner. In the acute treatment study, a single intravenous injection of DA-8159 also prevented the increase in urethral pressure in a dose-dependent manner. CONCLUSIONS: These results suggest that DA-8159 may be beneficial on lowering the urethral pressure associated with BPH via dilatation of the prostate, but a further evaluation of the efficacy on humans needs to be performed.     

The effect of DA-8159 on corpus cavernosal smooth muscle relaxation and penile erection in diabetic rabbits

A previous study showed that DA-8159, a potent type 5 phosphodiesterase inhibitor, enhanced the relaxation of the smooth muscles in the normal rabbit corpus cavernosum. In this study, we investigated the in vitro effects of DA-8159 on cavernosal smooth muscle relaxation and the in vivo erectogenic potential in diabetic rabbits, since erectile dysfunction is a well-known sequela of diabetes mellitus. Diabetes mellitus was induced in male New Zealand White rabbits with alloxan monohydrate. Cavernosal strips from age-matched control and 8-week diabetic animals were mounted in organ baths. The relaxation responses to sodium nitroprusside (10^-910^-5 M), a nitric oxide donor, were assessed in the presence or absence of DA-8159 (10^-910^-6 M). For the penile erection test, DA-8159 was given orally (1~10 mg/kg) to diabetic rabbits and the length of the uncovered penile shaft was measured in a time-course manner in the presence or absence of intravenous sodium nitroprusside. The sodium nitroprusside-stimulated relaxations were significantly impaired in the corpus cavernosum from the diabetic group (IC₅₀=1.07×10^-6 M following 8 weeks of diabetes mellitus; compared with 0.48×10^-6 M for age-matched controls). DA-8159 significantly and dose-dependently enhanced the sodium nitroprusside-stimulated relaxation in the diabetic groups. In addition, DA-8159 induced a dose-dependent penile erection in diabetic rabbits, which was potentiated by intravenous sodium nitroprusside. These results suggest that DA-8159 is an effective treatment for diabetic erectile dysfunction but further evaluation of the efficacy on human needs to be performed.