糖尿病ED兔模型阴茎海绵体神经型一氧化氮合酶的表达特征

Expression of neuronal nitric oxide synthase in corpus cavernosum with diabetic erectile dysfunction： experiment with rabbits

目的研究兔糖尿病模型勃起功能障碍（ED）发生过程中，阴茎海绵体神经型一氧化氮合酶（nNOS）表达的变化，探讨糖尿病性ED的分子机制。方法采用四氧嘧啶注射方法建立兔糖尿病性ED模型（n=14），以正常兔为对照组（n=14），比较给药后15、30和45d，两组电刺激盆神经前后海绵体内压（ICP）和系统动脉压（SAP）的变化。采用反转录聚合酶链反应（RT-PCR）、免疫组织化学和蛋白质印迹方法，检测给药后15、30和45d兔阴茎海绵体组织中nNOS的表达水平。结果四氧嘧啶注射后1周，70％（35／50）兔血糖浓度高于10mmol／L。给药后15～45d，共40％（14／35）糖尿病模型兔成为糖尿病ED模型，各时间段电刺激盆神经前后ICP差值均低于对照组（均P〈0．01），而电刺激前后SAP差值各组间差异无统计学意义（均P〉0．05）。RT-PCR分析结果显示，给药后15、30和45d，兔阴茎海绵体nNOS mRNA（0．670±0．030，0．451±0．012和0．206±0．023），均显著低于对照组（0．817±0．010，0．814±0．020和0．802±0．007，均P〈0．05），且呈时间依赖性下降（P〈0．05）。免疫组织化学和蛋白质印迹结果显示，给药后15、30和45d，糖尿病性ED兔阴茎海绵体nNOS蛋白（0．713±0．014、0．424±0．007和0．337±0．009）也均显著低于对照组（0．797±0．015、0．706±0．020和0．750±0．022，均P〈0．05），并且随糖尿病进程发展而逐渐降低（均P〈0．05），与RT-PCR分析结果一致。结论阴茎海绵体nNOS的表达量下降可能是导致糖尿病性ED的发病机制之一。

Objective To investigate the expression characteristics of neuronal nitric oxide synthase （nNOS） in the corpus cavernosum of diabetic erectile dysfunction （ED）. Methods Fifty rabbits underwent single intravenous injection of alloxan （100 mg/kg）. Blood glucose, system arterial pressure （SAP）, and intracavemosal pressure （ICP） were measured 15,30, and 45 days later. The rabbits with the blood glucose 〉 10 mmol/L were used as diabetic models and those with the ICP lower than the normal control group by more than 25% were used as diabetic ED models. RT-PCR, immunohistochemistry, and Western-blotting were used to detect the expression of nNOS in the corpus cavernosum. Results Seven days after the alloxan injection the blood glucose levels of 35 rabbits （70%）were 〉 10 mmol/L. 40% rabbits （14/35） were were used as diabetic ED models. Compared with control group, the ICP 15, 30, and 45 days after alloxan injection were considerately decreased in diabetic ED rabbits （ all P 〈 0.01 ）, and there was no significant difference in SAP between the two groups （ all P 〉 0.05 ）. The relative values of nNOS mRNA expression 15, 30, and 45 days after alloxan injection of diabetic ED rabbits were 0. 670±0. 030,0. 451±0. 012, and 0. 206±0. 023 respectively, all significantly lower than those of the control group （0.817±0.010, 0.814±0. 020, and 0. 802±0. 007 respectively, all P 〈 0.05 ）. Western blotting showed that the relative values of nNOS 15, 30, and 45 days after alloxan injection of the ED rabbits were 0. 713±0. 014, 0. 424±0. 007,and 0.337±0. 009 respectively, all significantly lower than those of the control group （0. 797±0. 015, 0. 706±0. 020, and 0. 750±0. 022 respectively, all P 〈 0.05 ）. Conclusion Decreased expression of nNOS in corpus cavernosum is one of possible pathway of diabetic ED.