Abdel Aziz M Talaat, El-Asmer Mohamed Farid, Mostafa Taymour, Mostafa Samia, Atta Hazem, Aziz Wassef M Abdel, Fouad Hanan, Rashed Laila, Sabry Dina, Mahfouz Soheir
Molecular Biology Unit, Medical Biochemistry Department, Faculty of Medicine, Cairo University, Cairo, Egypt.
J Sex Med. 2007 Jul;4(4 Pt 2):1098-107. doi: 10.1111/j.1743-6109.2007.00533.x.
Heme oxygenase (HO) enzyme catalyzes the rate limiting step in oxidative degradation of heme to biliverdin and carbon monoxide (CO). CO has been shown to share many properties with nitric oxide (NO), including activation of guanyl cyclase, signal transduction, and gene regulation.
To assess the signaling pathways mediating cavernous tissues response to sildenafil citrate intake experimentally.
In dissected cavernous tissues; detection of HO-1, HO-2 and nueronal nitric oxide synthase (nNOS) gene expressions by reverse transcriptase polymerase chain reaction (RT-PCR), HO enzyme activity assay, HO-1, HO-2 protein detection by Western blot, cyclic guanosine monophosphate (cGMP) tissue levels by enzyme linked immunosorbent assay (ELISA) and histopathology.
Two hundred forty Sprague-Dawley rats divided into five equal groups were investigated: group (Gr) 1, controls received regular diet; Gr 2, received sildenafil citrate 4 mg/kg orally; Gr 3, received the same dose of sildenafil added to HO inducer, diferuloylmethane; Gr 4, received sildenafil added to HO inhibitor, zinc protoporphyrin, and Gr 5, received sildenafil kg orally by gastric tube. Gr 3 received the same dose of sildenafil added to HO inducer, added to nitric oxide synthase inhibitor, L-Nitroarginine methylester. Twelve rats from each group were sacrificed by cervical dislocation successively after 1/2, 1, 2, and 3 hours from the intake.
HO-2 gene expression was demonstrated in all groups. HO-1 was not expressed in controls, expressed in Gr 2, accentuated in Gr 3, and attenuated in Gr 4 and 5. These results were confirmed by Western blot. The nNOS was expressed in controls, increased in Gr 2 and 3, and decreased in Gr 4 and 5. HO enzyme activity and cGMP levels were significantly elevated in Gr 2, accentuated in Gr 3, and significantly decreased in Gr 4 and 5 compared to controls. Vasodilatations were observed in cavernous tissues of histopathologic sections of Gr 2 and increased in those of Gr 3.
Sildenafil citrate actions may be mediated by up-regulation of HO-1 gene expression.
血红素加氧酶（HO）催化血红素氧化降解为胆绿素和一氧化碳（CO）的限速步骤。已表明CO与一氧化氮（NO）具有许多共同特性，包括激活鸟苷酸环化酶、信号转导和基因调控。
通过实验评估介导海绵体组织对枸橼酸西地那非摄入反应的信号通路。
在解剖的海绵体组织中；通过逆转录聚合酶链反应（RT-PCR）检测HO-1、HO-2和神经元型一氧化氮合酶（nNOS）基因表达，进行HO酶活性测定，通过蛋白质印迹法检测HO-1、HO-2蛋白，通过酶联免疫吸附测定（ELISA）检测环磷酸鸟苷（cGMP）组织水平以及进行组织病理学检查。
将240只Sprague-Dawley大鼠分成五个相等的组进行研究：第1组为对照组，给予常规饮食；第2组口服4mg/kg枸橼酸西地那非；第3组给予相同剂量的西地那非并添加HO诱导剂二阿魏酰甲烷；第4组给予西地那非并添加HO抑制剂锌原卟啉；第5组通过胃管口服西地那非。第3组给予相同剂量的西地那非并添加HO诱导剂，同时添加一氧化氮合酶抑制剂L-硝基精氨酸甲酯。每组12只大鼠在摄入药物后1/2、1、2和3小时依次通过颈椎脱臼处死。
所有组均检测到HO-2基因表达。HO-1在对照组未表达，在第2组表达，在第3组增强，在第4组和第5组减弱。这些结果通过蛋白质印迹法得到证实。nNOS在对照组表达，在第2组和第3组增加，在第4组和第5组减少。与对照组相比，第2组HO酶活性和cGMP水平显著升高，在第3组增强，在第4组和第5组显著降低。在第2组组织病理学切片的海绵体组织中观察到血管舒张，在第3组中增强。
枸橼酸西地那非的作用可能通过上调HO-1基因表达介导。
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