可分泌表达人降钙素基因相关肽重组腺相关病毒对糖尿病大鼠阴茎勃起的作用

Effect of Secretory Human Calcitonin Gene-related Peptide Recombinant AAV on Penile Erection in Streptozotocin-induced Diabetic Rat

目的:探讨重组腺相关病毒(rAAV)介导人降钙素基因相关肽(hCGRP)基因转移在糖尿病大鼠阴茎海绵体平滑肌分泌表达及其对阴茎勃起的作用。方法:建立链佐脲菌素(STZ)糖尿病大鼠模型,随机分为3组,分别将VssHGCMV-hCGRP、VssCMV-GFP和rAAV空病毒液注射于阴茎海绵体。在注射后5 d,采用SMUP-PC型生物信号处理系统检测阴茎背神经电刺激诱发的阴茎勃起反应及海绵体内压(ICP)变化。切取海绵体组织,通过免疫组化技术和激光共聚焦显微镜分别检测hCGRP和绿色荧光蛋白(GFP)表达,以放射免疫法检测组织中环磷酸腺苷(cAMP)和环磷酸鸟苷(cGMP)变化。结果:在VssCMV-GFP转染后5 d,显示阴茎海绵体内几乎所有组织均有广泛的GFP表达,而rAAV空病毒转染的海绵体则无GFP表达。VssHGCMV-hCGRP转染STZ诱导的糖尿病大鼠后5d,电刺激阴茎背神经可诱发明显的阴茎勃起,监测ICP明显增高[(60.5±4.5)mm Hg,1 mm Hg=0.133kPa],而对rAAV空病毒转染的对照组STZ糖尿病大鼠以同样的参数电刺激阴茎背神经则无勃起反应,ICP无明显增加[(22.3±1.3)mm Hg],两组差异有显著性(P<0.01)。免疫组化观察显示在VssHGCMV-hCGRP转染的STZ糖尿病大鼠阴茎海绵体组织中hCGRP表达增强,同时当电刺激阴茎背神经诱发勃起反应时,海绵体内cAMP和cGMP水平均升高,分别为(48.4±6.5)nmol/L和(21.2±13.6)nmol/L,较rAAV空病毒组[(16.7±2.5)nmol/L和(0.42±0.12)nmol/L]明显增高(P<0.01)。结论:经阴茎海绵体内注射重组腺相关病毒VssHGCMV-hCGRP在糖尿病大鼠阴茎海绵体内获得了hCGRP转基因高效表达,其可增加阴茎背神经电刺激诱发的阴茎ICP和勃起反应。

Objective： To determine whether recombinant adeno-associated virus- mediated overexpression of hCGRP in the corpus cavernosum can affect the continuous production of hCGRP in the penile tissue and enhance erectile responses in STZ-induced diabetic rats. Methods： Diabetes mellitus was induced by a single intraperitoneal injection of 60 mg/kg streptozotocin in male SD rats. VssHGCMV- hCGRP, VssCMV-GFP and rAAV solution were injected into the corporal cavernosum of STZ-induced diabetic rats, respectively. The corporal tissue was obtained from groups of 8 rats on day 5 post-injection, and the expressions of CGRP and GFP in cavernosal tissue were detected using immunohistochemisry and laser scanning confocal microscopy, respectively. Cavernosal tissue cAMP and cGMP levels were measured using rediaoimmunoassay. On day 5 post-injection, intracavernous pressure induced by electrostimulation of penile dorsal nerves was measured and recorded with a biological signal processing system in each group rat. Results： rAAV transduction efficiency of GFP reporter gene was measured by laser scanning confocal microscopy and was observed in the penile tissue,especially in the corporal cavernosum and the vessel 5 days after transfection with VssCMV-GFP. Immunohistochemistry showed that the CGRP increased in the corporal cavernosum. In addition,both cAMP and cGMP levels in the corpora cavernosa transfected with VssHGCMV-hCGRP were significantly increased, compared with controls [ （ 48.4 ± 6.5 ） nmol/L and （ 21.2 ± 13.6 ） nmol/L vs （ 16.7 ± 2.5 ） nmol/L and （0.42±0.12） nmol/L, respectively]. More importantly, 5 days after administration of VssHGCMV-hCGRP,a significant increase was observed in the erectile response to penile dorsal nerve stimulation in the diabetic rat [ （60.5 ± 4.5） mm Hg vs （ 22.3 ± 1.3 ） mm Hg]. Conclusions ： This results demonstrate that rAAV-mediated transfer of the CGRP gene can increase production of endogenous CGRP, cAMP and cGMP in corpora cavernosa of STZ-induced diabetic rats. Moreover, overexpression of CGRP enhances ICP and the erectile response to penile dorsal nerve stimulation in the diabetic rat.