淫羊藿次苷Ⅱ在防治大鼠放射损伤导致的勃起功能障碍中的作用

Preventive and therapeutic effects of Icariside Ⅱ on radiation injury-induced erectile dysfunction in rats

目的:探究淫羊藿次苷Ⅱ在大鼠放射损伤导致的阴茎勃起功能障碍(Ri-ED)中的防治作用。方法:随机选取10周龄雄性SD大鼠24只,前列腺局部给予20 Gy的单次X线照射,并随机分为放射损伤组(Ri-ED组,存活6只,死亡6只)和淫羊藿次苷Ⅱ治疗组[4.5 mg/(kg·d),存活9只,死亡3只]。另取6只SD大鼠作为阴性对照组,连续灌胃4周并药物洗脱期2周后,通过检测阴茎海绵体内压/平均动脉压(ICP/MAP)评估阴茎勃起功能。阴茎组织标本行免疫荧光染色、免疫组织化学染色、Masson三色染色、Western印迹以及氧化应激指标的检测。结果:放射损伤后,大鼠ICPmax/MAP(0.76±0.09 vs 0.42±0.06,P<0.01)、阴茎海绵体nNOS阳性神经纤维数量(10.17±2.64 vs 3.17±1.72,P<0.01)、内皮细胞含量(1.39±0.30 vs 0.35±0.12,P<0.01)、nNOS(0.42±0.08 vs 0.08±0.01,P<0.01)及eNOS(0.99±0.24 vs 0.12±0.08,P<0.01)表达量均较阴性对照显著降低。Ri-ED组与阴性对照组相比具有较低的SOD活性[(153.50±34.06) U/mg prot vs(343.73±58.57)U/mg prot,P<0.01],且具有更高的MDA水平[(3.25±0.21) nmol/mg prot vs(1.80±0.31) nmol/mg prot,P<0.01]。与Ri-ED组相比,ICAⅡ治疗能显著提高ICP/MAP(0.42±0.06 vs 0.66±0.07,P<0.01)、nNOS阳性神经纤维数量(3.17±1.72 vs 7.33±1.75,P<0.05),内皮细胞含量(0.35±0.12 vs 1.07±0.36,P<0.01),阴茎海绵体中nNOS(0.08±0.01 vs 0.16±0.05,P<0.05)与eNOS(0.12±0.08 vs 0.86±0.30,P<0.01)蛋白含量增高,并能显著减低MDA水平[(3.25±0.21) nmol/mg prot vs(2.17±0.55) nmol/mg prot,P<0.05]。此外,淫羊藿次苷Ⅱ治疗可以有效降低放射损伤导致的大鼠的死亡率。结论:淫羊藿次苷Ⅱ对放射损伤引发的ED和病理变化具有显著的改善作用,其机制可能与其改善放射导致的氧化应激有关。而且,淫羊藿次苷Ⅱ在动物实验中能显著降低动物死亡率。

Objective: To explore the preventive and therapeutic effects of Icariside Ⅱ(ICAⅡ) on radiation injury-induced ED(Ri-ED) in rats. Methods: Twenty-four 10-week-old male SD rats received exposure of the prostate to single X-ray irradiation of 20 Gy, and were randomly equally divided into an Ri-ED group(6 survived and 6 died) and a treatment group treated with ICAⅡ at 4.5 mg/kg/d(9 survived and 3 died). Another 6 SD rats were taken as negative controls. After 4 weeks of continuous intragastric administration and 2 weeks of drug elution, the erectile function of the rats was evaluated by measurement of the maximum intracavernous pressure/mean arterial pressure(ICPmax/MAP), and the penile tissues were subjected to immunofluorescence staining, immunohistochemistry, Masson’s trichrome staining, Western blot and detection of oxidative stress indicators. Results: Compared with the negative controls, the rats in the Ri-ED group showed significant decreases in ICPmax/MAP(0.76 ± 0.09 vs 0.42 ± 0.06, P < 0.01), the number of nNOS-positive nerve fibers in the corpus cavernosum(10.17 ± 2.64 vs 3.17 ± 1.72, P < 0.01), the content of endothelial cells(1.39 ± 0.30 vs 0.35 ± 0.12, P < 0.01), the expressions of nNOS(0.42 ± 0.08 vs 0.08 ± 0.01, P < 0.01) and eNOS(0.99 ± 0.24 vs 0.12 ± 0.08, P < 0.01) and the activity of superoxide dismutase(SOD)([343.73 ± 58.57] vs [153.50 ± 34.06] U/mg prot, P < 0.01), but an increase in the malondialdehyde(MDA) level([1.80 ± 0.31] vs [3.25 ± 0.21] nmol/mg prot, P < 0.01). In comparison with the Ri-ED group, the animals treated with ICAⅡ exhibited remarkably increased ICP/MAP(0.42 ± 0.06 vs 0.66 ± 0.07, P < 0.01), number of nNOS-positive nerve fibers(3.17 ± 1.72 vs 7.33 ± 1.75, P < 0.05), content of endothelial cells(0.35 ± 0.12 vs 1.07 ± 0.36, P < 0.01), and expressions of nNOS(0.08 ± 0.01 vs 0.16 ± 0.05, P < 0.05) and eNOS(0.12 ± 0.08 vs 0.86 ± 0.30, P < 0.01) in the corpus cavernosum, but a decreased level of MDA([3.25 ± 0.21] vs [2.17 ± 0.55] nmol/mg prot, P < 0.05). In addition, ICAⅡ effectively reduced radiation injury-induced mortality of the rats. Conclusion: IcarisideⅡ can significantly improve ED and pathological changes and reduce mortality caused by radiation injury in rats, which may be related to its ability of improving radiation-induced oxidative stress.