National Research Center for Sexual Medicine and Department of Urology, Inha University School of Medicine, Incheon, Korea.
J Sex Med. 2013 Dec;10(12):2912-27. doi: 10.1111/jsm.12278. Epub 2013 Aug 12.
Erectile dysfunction (ED) is a highly prevalent complication of diabetes, and the severity of endothelial dysfunction is one of the most important factors in reduced responsiveness to oral phosphodiesterase type 5 inhibitors.
To study the effects of human angiopoietin-4 (Ang-4) protein on erectile function in diabetic mice.
Diabetes was induced by intraperitoneal injection of streptozotocin into 8-week-old C57BL/6J male mice. At 8 weeks after the induction of diabetes, the animals were divided into four groups: control nondiabetic mice and diabetic mice receiving two successive intracavernous injections of phosphate buffered saline (days -3 and 0), a single intracavernous injection of Ang-4 protein (day 0), or two successive intracavernous injections of Ang-4 protein (days -3 and 0).
One week after treatment, we measured erectile function by electrical stimulation of the cavernous nerve. The penis was harvested and stained with hydroethidine or antibodies to Ang-4, platelet/endothelial cell adhesion molecule-1, and phosphorylated endothelial nitric oxide synthase (eNOS). We also determined the differential expression of Ang-4 in cavernous tissue in the control and diabetic mice. The effect of Ang-4 protein on the phosphorylation of Tie-2, Akt, and eNOS was determined in human umbilical vein endothelial cells (HUVECs) by Western blot.
The cavernous expression of Ang-4 was downregulated in diabetic mice; Ang-4 was mainly expressed in endothelial cells. Local delivery of Ang-4 protein significantly increased cavernous endothelial content, induced eNOS phosphorylation, and decreased the generation of superoxide anion and apoptosis in diabetic mice. Ang-4 protein strongly increased the phosphorylation of Tie-2, Akt, and eNOS in HUVECs. Repeated intracavernous injections of Ang-4 induced significant restoration of erectile function in diabetic mice (87% of control values), whereas a single intracavernous injection of Ang-4 protein elicited modest improvement.
Cavernous endothelial regeneration by use of Ang-4 protein may have potential for the treatment of vascular disease-induced ED, such as diabetic ED.
勃起功能障碍（ED）是糖尿病的一种高发并发症，内皮功能障碍的严重程度是降低对口服磷酸二酯酶 5 抑制剂反应性的最重要因素之一。
研究人血管生成素-4（Ang-4）蛋白对糖尿病小鼠勃起功能的影响。
将链脲佐菌素腹腔注射到 8 周龄 C57BL/6J 雄性小鼠中诱导糖尿病。在糖尿病诱导后 8 周，将动物分为四组：非糖尿病对照小鼠和接受连续两次海绵体内磷酸缓冲盐水注射（第-3 天和 0 天）、单次海绵体内 Ang-4 蛋白注射（第 0 天）或连续两次海绵体内 Ang-4 蛋白注射（第-3 天和 0 天）的糖尿病小鼠。
治疗后 1 周，通过电刺激海绵体神经测量勃起功能。采集阴茎并用羟乙基二氢啶或抗 Ang-4、血小板/内皮细胞黏附分子-1 和磷酸化内皮型一氧化氮合酶（eNOS）抗体染色。还测定了对照组和糖尿病组海绵组织中 Ang-4 的差异表达。通过 Western blot 测定 Ang-4 蛋白对人脐静脉内皮细胞（HUVECs）中 Tie-2、Akt 和 eNOS 磷酸化的影响。
糖尿病小鼠海绵体 Ang-4 表达下调；Ang-4 主要在血管内皮细胞中表达。局部给予 Ang-4 蛋白可显著增加海绵体内皮含量，诱导 eNOS 磷酸化，并减少糖尿病小鼠超氧化物阴离子和细胞凋亡的产生。Ang-4 蛋白可强烈增加 HUVECs 中 Tie-2、Akt 和 eNOS 的磷酸化。重复海绵体内注射 Ang-4 可显著恢复糖尿病小鼠的勃起功能（达到对照组的 87%），而单次海绵体内注射 Ang-4 蛋白仅可适度改善。
使用 Ang-4 蛋白进行海绵体内皮再生可能有潜力治疗血管疾病引起的 ED，如糖尿病性 ED。
